Sporadic Chronic Lymphocytic Leukemia Research Articles

Predictive and Prognostic Molecular Biomarkers in Familial Chronic Lymphocytic Leukemia: A Pilot Monocentric Study

Background: Chronic lymphocytic leukemia (CLL) is the most common leukemia in the western world and the median age at diagnosis is 70 years. Family history of hemopathies and, more consistently, of CLL is a risk factor to develop the disease. The prevalence of blood diseases, and more specifically of CLL, in relatives of patients with CLL has been estimated at 13% and 7%, respectively. Familial CLL is defined as the presence of at least one first degree relative with CLL. Previous studies hypothesize the phenomenon of anticipation, which is the earlier onset and more aggressive course of a disease in the second generation of relatives, in familial CLL. Aims: The primary end point is to determine the prevalence of familial CLL in our court of patients with CLL and to confirm the phenomenon of anticipation. The secondary endpoints involve the comparison of the prevalence of clinical features and molecular biomarkers between familial and sporadic CLL; the comparison of the impact of clinical features and molecular biomarkers on patients’ clinical course in terms of time to treatment (TTT), time to next treatment (TTNT), progression-free survival (PFS) and overall survival (OS) between familial and sporadic CLL; the evaluation of response to treatment (ORR) in familial CLL compared to sporadic cases. Patients and methods: This is a retrospective monocentric study which consists of clinical and biological data collection from all patients with familial CLL. We enrolled 500 patients, which included 46 familial CLL and 454 sporadic CLL cases, diagnosed between January 1987 and April 2022. Patients’ characteristics were described by frequency tables for qualitative variables and position indicators for quantitative variables. The associations with clinical-biological parameters were analyzed using Chi-square or Fisher's exact test for the variables qualitative and Wilcoxon or Kruskal-Wallis test for quantitative variables. Survival was estimated with the Kaplan Meier method and compared by the log rank test. Results: The prevalence of familial CLL and familiarity for any other hemopathy in our population was 9.4% and 20% respectively. The median age at diagnosis was 65 years old in sporadic and 59 years old in familial CLL (p=0.018). Focusing on patients with familial CLL, our data confirmed the phenomenon of anticipation. In the first generation of patients with familial CLL (including father, mother, and older siblings), the median age at diagnosis was 69 years old (range 50-90), while in the second generation (including children and younger siblings) the median age at diagnosis was 57 years old (range 31-83). The mean difference between the two populations was of 12.6 years (17.5 years lower limit and 7.7 years upper limit), with a 95% confidence interval (p=0.00003). Concerning the IgHV mutational status, sporadic CLL showed mutated IgHV in 65% of the cases and unmutated IgHV in 35%, while familial CLL showed mutated IgHV in 35% of the cases and unmutated IgHV in 65% (p<0.001). No statistically significant difference was instead found for FISH nor for molecular biomarkers, including TP53, NOTHC1, BIRC3 and SF3B1 (Table 1). In our cohort, the time to treatment, time to next treatment and progression free survival for familial CLL appear to be shorter than for the control group, but those results are not statistically significant at the log rank test. Moreover, the overall response rate was significantly lower in patients with familial CLL: this data has never been reported by any study and it further confirms the rather aggressive course of the disease (Table 1). Familial CLL did not show any significant difference in overall survival compared to sporadic CLL. Conclusions: We confirmed the phenomenon of anticipation in our population. Moreover, we found higher rate of unmutated IgHV in familial CLL compared to sporadic controls, which would underlie a more aggressive course of the disease in this subset of patients. To define the molecular characteristics of familial CLL and to improve the significance of the survival analysis, we need to study a larger population of patients. Our monocentric experience is meant to be a pilot study which will be extended to other centers in Italy and opens the way to a better understanding of CLL clustering in families. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Rare Germline Variant in NFATC4 Associated with Familial Chronic Lymphocytic Leukemia

Chronic lymphocytic leukemia (CLL) has one of the highest familial risks of any cancer, with up to eightfold increased risk in first degree relatives of CLL patients. Genome-wide association studies (GWAS) have identified multiple common single nucleotide polymorphisms (SNPs) associated with risk, but these have modest effect. Similarly, identified germline variants associated with disease account for just a small minority of CLL patients, making familial CLL an attractive target for research, that could provide direct insight into pathobiology.We used whole exome sequencing (WES; Illumina) to search for rare germline variants (<1% Minor Allele Frequency) in 36 patients from 17 families with Mendelian-like CLL inheritance, where at least two affected family members were sequenced. Median age at diagnosis was 56.4 (range 41-72), 61% were male, 10/23 (43%) were IGHV -unmutated, and 5/24 (21%) had del17p and/or TP53 mutation. We found 3819 rare variants shared within all affected members of a given family. Of those, 71 non-synonymous variants were shared across at least 2 families, and 39 of these were predicted to be pathogenic by at least two commonly-used phenotype prediction tools. None of these variants are within known somatic CLL driver genes, nor were any found in genes near known CLL GWAS SNPs. In order to prioritize these variants, we assessed whether they were enriched among CLL cases (n = 646) as compared to ethnically matched normal population controls (n=8,920), a dataset we have recently reported (Tiao, Improgo et al, Leukemia). Using Fisher's exact test with Benjamini-Hochberg (BH) correction for multiple tests, we found that 27 of the 71 shared variants across multiple families were also enriched in unrelated CLL patients compared to controls. Among those, a rare variant of nuclear factor of activated T-cells 4 (NFATC4), rs200328372, was the most highly enriched in CLL (OR 20.8, Fisher-q-BH 0.026). This variant affects a splice acceptor site predicted to have a deleterious effect on the protein (FATHMM for non-coding variants). In a pathway analysis (MSigDB, DAVID) of genes carrying shared variants across families, NFATC4 together with SOS1 and PTPN7 were associated with the T-cell receptor, B-cell receptor, and MAP-kinase pathways, suggesting a possible role in CLL pathogenesis.The NFATC4 protein, also known as NFAT3, is part of a DNA-binding transcriptional complex that translocates to the nucleus after activation through dephosphorylation by calcineurin. This complex is involved in the inducible expression of cytokine genes in T cells, including interleukin (IL)-2 and IL-4. While NFATC1 has been implicated in CLL pathogenesis and was associated with more aggressive disease in a mouse model of CLL, the role of NFATC4 has not been elucidated. To further investigate this as well as its association with familial CLL, we compared gene expression profiling (GEP; Affymetrix U133 plus 2.0 array) data between familial and sporadic CLL patients and normal B-cells. While NFATC4 expression did not differ between normal B-cells (n=16) and CLL (n=143), it was significantly down-regulated in familial (n=47) as compared to sporadic (n=96) CLL cases (Mann-Whitney, p=0.005). In the 4 cases that harbor the shared risk variant, GEP results showed additional significant down-regulation of NFATC4 expression (Kruskal-Wallis, p=0.003 for all comparisons) (Figure 1).RNA sequencing (Illumina) demonstrated NFATC4 down-regulation in all CLL samples (not specifically in familial CLL as with GEP; n=100) versus normal B-cells (n=6; Mann-Whitney, p=-0.00024), suggesting a putative role for NFATC4 as a tumor suppressor. Since NFATC4 has over 30 alternatively spliced transcripts potentially affected by the rs200328372 variant, we used Cufflinks software to look at isoform-level RNA sequencing data, available on two relatives who carried this variant, compared to CLL cases and controls. Both relatives had reduced expression of all isoforms (Figure 2), suggesting that this mutation may reduce NFATC4 expression altogether. Studies of protein expression are ongoing.In conclusion, through rare germline variant analysis in familial CLL, we found a potentially deleterious variant of NFATC4 that is enriched in CLL. Subsequently, we used RNA sequencing data to show, for the first time, that NFATC4 expression is decreased in CLL versus normal B-cells, revealing a potential tumor suppressor mechanism in CLL. [Display omitted] DisclosuresBrown:Sun BioPharma: Consultancy, Research Funding; Gilead: Consultancy, Research Funding; Pharmacyclics: Consultancy; Redx: Consultancy; AstraZeneca: Consultancy; Pfizer: Consultancy; Janssen Oncology: Honoraria; AbbVie: Consultancy, Honoraria; Roche/Genentech: Consultancy; Celgene: Consultancy; Janssen: Consultancy; Infinity Pharmaceuticals: Consultancy; Astellas Pharma: Consultancy.

Association of elevated serumfree light chains with chronic lymphocytic leukemia and monoclonal B-cell lymphocytosis

Chronic lymphocytic leukemia (CLL) and its precursor, monoclonal B-cell lymphocytosis (MBL), are heritable. Serumfree light-chain (sFLC) measures are a prognostic factor for CLL, but their role in susceptibility to CLL is not clear. We investigated differences between sFLC measurements in pre-treatment serum from five groups to inform the association of sFLC with familial and sporadic CLL: (1) familial CLL (n = 154), (2) sporadic CLL (n = 302), (3) familial MBL (n = 87), (4) unaffected first-degree relatives from CLL/MBL families (n = 263), and (5) reference population (n = 15,396). The percent of individuals having elevated monoclonal and polyclonal sFLCs was compared using age-stratified and age- and sex-adjusted logistic regression models. In age groups >50 years, monoclonal sFLC elevations were increased in sporadic and familial CLL cases compared to the reference population (p’s < 0.05). However, there were no statistically significant differences in sFLC monoclonal or polyclonal elevations between familial and sporadic CLL cases (p’s > 0.05). Unaffected relatives and MBL cases from CLL/MBL families, ages >60 years, showed elevated monoclonal sFLC, compared to the reference population (p’s < 0.05). This is the first study to demonstrate monoclonal sFLC elevations in CLL cases compared to controls. Monoclonal sFLC levels may provide additional risk information in relatives of CLL probands.

Familial chronic lymphocytic leukemia in Israel: A disproportionate distribution among Ashkenazi Jews.

Relatives of patients with chronic lymphocytic leukemia (CLL) are at increased risk of developing CLL. Familial CLL is defined as more than one case of CLL among blood relatives, a phenomenon reported in approximately 5%-10% of all CLL patients. Given the known predisposition of CLL among Ashkenazi Jews, we studied the features of familial CLL in an Israeli population. This is a retrospective study, in which we reviewed the demographics, clinical characteristics, and outcomes of a total of 332 patients with CLL/small lymphocytic lymphoma. Familial CLL was recorded in 41 cases (12.3%) of the patients. The age at diagnosis was younger in patients with familial CLL (by almost 3.5years). Familial CLL was strongly associated with Ashkenazi Jewish origin. Patients with familial CLL more commonly presented with higher hemoglobin and lower serum β-2-microglobulin levels. No significant differences were detected between sporadic and familial CLL in disease stage, time to treatment, second cancers, or overall survival. Familial cases of CLL in an Israeli population show a disproportionate ethnic distribution toward Jews of Ashkenazi origin. The clinical characteristics and the overall outcome are not substantially different from sporadic cases.

Frecuencia de linfocitosis monoclonal de células B en familiares de pacientes con leucemia linfoide crónica

Introducción:La linfocitosis monoclonal de células B es una condición asintomática que se caracteriza por la circulación de pequeñas poblaciones clonales de linfocitos B en sangre periférica (menos de 5x109/L) que expresan un inmunofenotipo similar al de la leucemia linfoide cónica. Diferentes estudios basados en grandes series hospitalarias, han puesto de manifiesto un riesgo más elevado de los sujetos con linfocitosis monoclonal de células B de progresar a una leucemia linfoide crónica. En Colombia se desconoce el comportamiento de esta entidad hematológica, por tal razón se determinó su frecuencia en familiares de pacientes con leucemia linfoide crónica esporádica.Métodos:Estudio descriptivo transversal, se realizó citometría de flujo de 8 colores utilizando dos de los tubos del panel recomendado por Euro Flow para el diagnóstico de enfermedades linfoproliferativas crónicas de linfocitos B con modificaciones, además se hizo hibridación fluorescente in situ. Se realizó análisis univariado y bivariado.Resultados:La frecuencia de linfocitosis monoclonal de células B encontrada en los 51 familiares analizados fue del 2%, se trató de un participante del sexo femenino y 59 años de edad, con un recuento total de leucocitos de 7,7x109/L y un recuento de linfocitos B de 0,124x109/L; de estos 0,04x109/L eran células clonales con restricción de la cadena ligera kappa. Se encontraron reordenamientos del gen IGH (14q32).Conclusión:Se detectó linfocitosis monoclonal de células B en un familiar de paciente con leucemia linfoide cónica esporádica en una frecuencia similar a la informada en la población general.

Elevated Rates of Monoclonal Gammopathy in High-Risk Chronic Lymphocytic Leukemia Pedigrees

High-risk pedigrees can be a powerful design for disease gene discovery. Understanding tumor spectrum in high-risk pedigrees optimizes power for discovery, allows meaningful assessment of segregation and determination of familial risk. Many studies have observed that different hematological malignancies co-aggregate in families. In particular, we previously performed genealogical cluster analysis in the Utah Population Database and identified significant co-aggregation between chronic lymphocytic leukemia (CLL) and multiple myeloma (MM). We have also determined that the frequency of the pre-clinical state, monoclonal B-cell lymphocytosis (MBL), is elevated in high-risk CLL pedigrees. Here, we explore evidence for monoclonal gammopathies in high-risk CLL pedigrees using serum immunoglobulin (Ig) biomarkers.Monoclonal gammopathies are characterized by a clonal expansion of plasma cells that secrete a monoclonal Ig. We used two serum biomarker tests to indicate the existence of clonal Ig proteins: Freelite™ and Hevylite™ immunoassays. These were performed on 498 frozen serum samples: 163 population controls; 97 MM/MGUS cases; 114 CLL cases (91 sporadic CLL and 23 from high-risk pedigrees); and 124 relatives in CLL pedigrees. Freelite detects and quantitates free light chains (κ and λ). Hevylite detects and quantitates specific immunoglobulins (IgA, IgG or IgM) bound to specific light chains. We determined monoclonality if either assay indicated an abnormal κ/λ ratio (specifically in conjunction with increased total Ig-type for Hevylite).The majority of monoclonality identified (92%) included restricted free lights chains. Those involving monoclonal Ig heavy chains only were all positively confirmed by standard serum protein and/or immunofixation electrophoresis.We observed a background of monoclonal gammopathy in our control samples (5/163, frequency =0.031), consistent with the advanced age of this comparison set (average 67y). As expected, monoclonal gammopathy was evident in the MM/MGUS cases (38/97, frequency=0.392, p=3.5×10-14), which increased to frequency=0.732, for abnormal κ/λ ratio considered without requiring increase of the specific Ig-type for Hevylite. The absence of complete identification is likely due to our samples being from prevalent cases at different treatment stages, in addition to non-secretory disease. The CLL cases (sporadic or pedigree) exhibited very similar rates of suggested monoclonal gammopathy (together 43/114, frequency=0.377, p=6.5×10-14). Pedigree relatives also exhibited evidence of clonal Ig proteins (9/124, frequency=0.073). The frequency across all relatives was not statistically different than the control set; however, the relatives were substantially younger than controls (minimum age 20y). When relatives were restricted to those over 49y (with average 67y), the frequency increased to 0.095 and became statistically increased compared to controls (p=0.028). The 9 relatives with monoclonality were: 1 non-Hodgkin lymphoma NOS, 1 MBL case, 2 solid cancer cases, and 5 relatives with no known cancer diagnoses.In conclusion, using sensitive Ig biomarkers we find that individuals in high-risk CLL pedigrees are at a greater risk of monoclonal gammopathy than the general population. This observation is consistent with previous clustering results indicating co-aggregation and a possible genetic etiologic overlap between CLL and MM. Furthermore, these Ig quantitative measures offer detailed phenotypes for all pedigree members, creating more informative pedigrees, increasing the power for gene identification. These measures offer an avenue for exploiting similarities across B-cell malignancies and have the potential to improve our ability to identify at-risk individuals. DisclosuresNo relevant conflicts of interest to declare.

Monoclonal B-cell lymphocytosis in individuals from sporadic (non-familial) chronic lymphocytic leukemia families persists over time, but does not progress to chronic B-cell lymphoproliferative diseases.

BackgroundMonoclonal B-cell lymphocytosis is classified as ‘high-count or clinical’ monoclonal B-cell lymphocytosis and ‘low-count or population’ monoclonal B-cell lymphocytosis. Previously, 167 first-degree relatives pertaining to sporadic (non-familial) chronic lymphocytic leukemia families were studied and the presence of seven monoclonal B-cell lymphocytosis individuals was reported.ObjectiveThe aim of this report is to describe the outcomes of five of the original monoclonal B-cell lymphocytosis individuals.MethodsFlow cytometry analysis was performed on mononuclear cells previously isolated from peripheral blood samples. A strategy of sequential gating designed to identify the population of CD19+/CD5+ B-lymphocytes was used and, subsequently, the monoclonal B-cell lymphocytosis cells were characterized by the CD20weak/CD79bweak/negative phenotype.ResultsThe monoclonal B-cell lymphocytosis clone showed consistent stability over time with little variations in size. After a median follow-up of 7.6 years, none of the five monoclonal B-cell lymphocytosis individuals progressed to chronic lymphocytic leukemia or other B-cell lymphoproliferative disease.ConclusionsThe data of this study suggest that chronic lymphocytic leukemia-like monoclonal B-cell lymphocytosis detected in the context of sporadic chronic lymphocytic leukemia families is not prone to clinical evolution and could be just a sign of immune senescence.

Inherited susceptibility to chronic lymphocytic leukemia: evidence and prospects for the future.

Chronic lymphocytic leukemia (CLL) is the most common leukemia in the United States and one of the most heritable cancers. A family history of the disease is perhaps the best defined risk factor, and approximately 15-20% of CLL patients have a family member with CLL or a related lymphoproliferative disorder. Much effort has been devoted to trying to elucidate the mechanisms underlying this genetic risk. Familial CLL appears to be clinically and biologically similar to sporadic CLL, and most if not all CLL appears to be preceded by monoclonal B-cell lymphocytosis (MBL), which does appear to occur at higher frequency in relatives in families with CLL. Neither linkage studies nor candidate gene association studies have proven particularly informative in CLL, but genomewide association studies have identified multiple low-risk variants that together explain about 16% of the familial risk of CLL. Studies of individual families have identified higher-risk single nucleotide polymorphisms or copy number variants associated with disease risk in those families. Current efforts to identify additional risk loci are focused on applying next-generation sequencing to the germline of informative CLL families as well as individuals with sporadic CLL.

Novel Germline Genetic Variants Associated with Familial Chronic Lymphocytic Leukemia (CLL)

Abstract 465CLL is among the most heritable of all cancers. To understand the genetic basis of this heritability, we have undertaken a comprehensive genomic analysis of familial CLLs including copy number analysis, gene expression profiling (GEP) and whole exome sequencing (WES). First, we examined whether familial and sporadic cases differ in the spectrum of acquired somatic mutations by WES of tumor and germline DNA of 36 familial CLLs (from 31 affected families). Compared to 55 sporadic CLLs, we observed that the somatic mutation rate in the familial CLLs was similar (mean 0.89 mutations/Mb (range 0.29–3.06) for the sporadics vs mean 0.97/Mb (range 0.11–3.78) for the familials, p=0.40). We also examined the spectrum of somatic mutations by testing for enrichment of 9 recently identified putative tumor drivers in our large CLL sequencing study (reported elsewhere in this meeting). We observed a similar distribution of these recurrent CLL mutations among the 36 familial CLLs as the 55 sporadic CLLs. These results were further confirmed by genotyping of the CLL driver mutations in an additional 32 familial and 67 sporadic CLLs. Collectively, these studies suggest that while the predisposing germline events may differ between familial and sporadic CLL, the spectrum of mutations and pattern of mutagenesis appear similar in the established CLL tumors.We therefore proceeded to examine the genetic characterization of germline DNA to identify predisposing loci, which we hypothesized might be enriched in a familial disease context. We first examined germline copy number variations (CNVs), which have not been previously characterized in this disease. We used high resolution Affymetrix 6.0 SNP arrays to study both tumor and germline DNA of 58 individuals representing 44 different families with CLL and lymphoproliferative disorders (LPDs). We identified two families (A and B) with autosomal dominant inheritance of CLL who carried distinct germline CNVs that affect genes previously implicated in CLL. Members of Family A carried a 525 kb germline deletion targeting DLEU7 at 13q14, but not affecting DLEU2, miR-15a, or miR-16–1. Importantly, by examining the tumor genome from these family members, we observed a uniform loss of the second allele of DLEU7 in 2/2 available CLLs from this family, suggesting an acquired “second hit” of a tumor suppressor gene. These findings underline the complexity of the most common somatically acquired copy number aberration (CNA) in CLL, 13q14 deletion, by demonstrating the role of additional regions other than the heavily investigated miRNA cluster. Members of Family B carried a 720 kb germline gain of 6p25 affecting the IRF4 gene, previously implicated in CLL through the identification of a GWAS risk allele located in the 3’ UTR of IRF4, as well as the recent description of a recurrent somatic mutation affecting 1.5% of CLL cases. In Family B, the coding regions of the four genes located in this 6p gain, namely IRF4, DUSP22, EXOC2 and HUS1B, were sequenced, and no somatic mutations or novel SNPs were identified. However, the 6p gain in Family B represents an allele-specific enrichment of the haplotype carrying the GWAS risk SNP and, as previously described for that allele, results in lower expression of IRF4 in the two CLLs tested in this family. GEP further identified a signature associated with 6p gain that preserved low expression of IRF4 and showed high expression of KLF6. These results demonstrate that germline CNVs may facilitate the “path to cancer” by providing either an allelic deletion of a tumor suppressor or an amplification of a risk allele.As most familial CLL cases have not been accounted for by known SNPs or germline CNVs, we have initiated an in depth analysis of the WES germline results from familial cases compared to both sporadic CLL patients and normal individuals. Candidate variants have been filtered to exclude all SNPs described in the 1000 Genomes project and to focus on highly conserved sites. Thus far we have found that rare germline variants in patients with familial CLL contain a rich source of loci with relevance to B cell biology. Studies in progress are focused on further analysis of informative families and functional analyses of candidate variants. These comprehensive genomic analyses are expected to identify multiple cooperating genetic mechanisms that contribute to CLL pathogenesis, including CNVs and somatic and germline mutations. Disclosures:No relevant conflicts of interest to declare.

Genome-wide association study identifies a novel susceptibility locus at 6p21.3 among familial CLL

AbstractPrior genome-wide association (GWA) studies have identified 10 susceptibility loci for risk of chronic lymphocytic leukemia (CLL). To identify additional loci, we performed a GWA study in 407 CLL cases (of which 102 had a family history of CLL) and 296 controls. Moreover, given the strong familial risk of CLL, we further subset our GWA analysis to the CLL cases with a family history of CLL to identify loci specific to these familial CLL cases. Our top hits from these analyses were evaluated in an additional sample of 252 familial CLL cases and 965 controls. Using all available data, we identified and confirmed an independent association of 4 single-nucleotide polymorphisms (SNPs) that met genome-wide statistical significance within the IRF8 (interferon regulatory factor 8) gene (combined P values ≤ 3.37 × 10−8), located in the previously identified 16q24.1 locus. Subsetting to familial CLL cases, we identified and confirmed a new locus on chromosome 6p21.3 (combined P value = 6.92 × 10−9). This novel region harbors the HLA-DQA1 and HLA-DRB5 genes. Finally, we evaluated the 10 previously reported SNPs in the overall sample and replicated 8 of them. Our findings support the hypothesis that familial CLL cases have additional genetic variants not seen in sporadic CLL. Additional loci among familial CLL cases may be identified through larger studies.

Familial chronic lymphocytic leukemia

Families with multiple individuals affected with chronic lymphocytic leukemia (CLL) and other related B-cell tumors have been described in the literature and strong familial aggregation has been seen in population studies. However, predisposing germline mutations have not been identified. We will discuss the spectrum of conditions associated with CLL in families and the advances in identifying the underlying susceptibility genes. Familial CLL does not appear to differ substantially from sporadic CLL in terms of prognostic markers and clinical outcome, although it may be associated with more indolent disease. The precursor condition, monoclonal B-cell lymphocytosis, also aggregates in CLL families. Linkage studies have been conducted in high-risk CLL families to screen the whole genome for susceptibility loci but no gene mutations have yet been identified by this method. Association studies of candidate genes have implicated several genes as being important in CLL but more studies are needed. Results from whole-genome association studies are promising. The ability to conduct large-scale genomic studies in unrelated CLL patients and in high-risk CLL families will play an important role in detecting susceptibility genes for CLL over the next few years and thereby help to delineate causal pathways.

Non-codingRNA sequence variations in human chronic lymphocytic leukemia and colorectal cancer

Cancer is a genetic disease in which the interplay between alterations in protein-coding genes and non-coding RNAs (ncRNAs) plays a fundamental role. In recent years, the full coding component of the human genome was sequenced in various cancers, whereas such attempts related to ncRNAs are still fragmentary. We screened genomic DNAs for sequence variations in 148 microRNAs (miRNAs) and ultraconserved regions (UCRs) loci in patients with chronic lymphocytic leukemia (CLL) or colorectal cancer (CRC) by Sanger technique and further tried to elucidate the functional consequences of some of these variations. We found sequence variations in miRNAs in both sporadic and familial CLL cases, mutations of UCRs in CLLs and CRCs and, in certain instances, detected functional effects of these variations. Furthermore, by integrating our data with previously published data on miRNA sequence variations, we have created a catalog of DNA sequence variations in miRNAs/ultraconserved genes in human cancers. These findings argue that ncRNAs are targeted by both germ line and somatic mutations as well as by single-nucleotide polymorphisms with functional significance for human tumorigenesis. Sequence variations in ncRNA loci are frequent and some have functional and biological significance. Such information can be exploited to further investigate on a genome-wide scale the frequency of genetic variations in ncRNAs and their functional meaning, as well as for the development of new diagnostic and prognostic markers for leukemias and carcinomas.

Inherited predisposition to chronic lymphocytic leukemia

Inherited susceptibility to chronic lymphocytic leukemia (CLL) has been recognized for decades. Approximately 10% of individuals with CLL report a family history of CLL or a related lymphoproliferative disorder, and genetic predisposition is the best understood risk factor for CLL. Studies of familial CLL have suggested that the disease features are largely similar to sporadic CLL, although recent data suggest that familial CLL may more commonly show somatic hypermutation of the immunoglobulin heavy-chain variable region, suggesting a more indolent disease course. Monoclonal B-cell lymphocytosis (MBL) has been identified recently as a likely precursor to CLL; it is found in the general population with increasing age and enriched in unaffected relatives of individuals with familial CLL. Studies of MBL as well as mouse models of CLL may lead to better understanding of early CLL pathogenesis that is relevant to familial predisposition. To date, the identification of genes that predispose to familial CLL has been slow, primarily due to the relatively few families available for study, the small size of those families and disease causation most likely by multiple genes that each confer smaller risks. In the coming years, the application of systematic genomics approaches to familial CLL should, hopefully, lead to the identification of novel loci involved in the disease.

Increased serum BAFF (B-cell activating factor of the TNF family) level is a peculiar feature associated with familial chronic lymphocytic leukemia

In a series of 84 chronic lymphocytic leukemia (CLL) patients we sought to establish whether BAFF (B-cell activating factor of the TNF family) circulating levels correlated with clinical characteristics of disease. BAFF serum levels were significantly higher in 20 healthy controls (i.e., median 695 ng/mL, range 389–1040) in comparison to the whole population of CLL patients (median 376, range 93–8914; P < 0.0001). After setting a cut-off at the median value observed in healthy controls (i.e., 695 ng/mL) we found that 6 out of 15 (40%) patients with familial CLL had increased BAFF levels while the same occurred only in 5 out of 64 (7.2%) patients with sporadic CLL ( P = 0.0007). No significant difference in age ( P = 0.82), sex ( P = 0.97), Binet clinical stage ( P = 0.20), incidence of autoimmune hemolytic anemia (AIHA) or immune thrombocytopenia (ITP) ( P = 0.47), mutational status of IgVH ( P = 1.00), CD38 ( P = 0.34) and ZAP-70 expression ( P = 0.16) could be detected between patients with sporadic and familial CLL, respectively. The only feature characterizing familial CLL patients was a higher serum BAFF level ( sporadic CLL 336 ng/mL, range 93–925; familial CLL 601 ng/mL, range 138–8914; P = 0.002). Our data suggest that BAFF levels are elevated in patients with familial CLL. The small cohort of patients used implies that a larger study is needed to reinforce the observation.

Insight into the pathogenesis of chronic lymphocytic leukemia (CLL) through analysis of IgVH gene usage and mutation status in familial CLL

AbstractTo address the proposition that familial B-cell chronic lymphocytic leukemia (CLL) may exhibit a more restricted phenotype than sporadic CLL with respect to immunoglobulin gene usage or ontogenic development, we compared immunoglobulin (Ig) heavy chain variable region (VH) gene usage and IgVH mutation status in 327 patients with CLL from 214 families with 724 patients with sporadic cases. The frequency of mutated CLL was higher in familial CLL (P < .001), and there was evidence of intrafamilial concordance in mutation status (P < .001). The repertoire and frequency of IgVH usage was, however, not significantly different between familial and sporadic CLL. Furthermore, IgVH usage was not correlated between affected members of the same family. These observations provide evidence that familial CLL is essentially indistinguishable from sporadic CLL, favoring a genetic basis to disease development in general rather than a simple environmental etiology.

Immunophenotypic features distinguishing familial chronic lymphocytic leukemia from sporadic chronic lymphocytic leukemia

Familial chronic lymphocytic leukemia (CLL) has the most frequent familial aggregation among hematological malignancies. Familial CLL families have been studied to identify susceptibility genes and other factors that contribute in the etiology of CLL. To date no study has been conducted to evaluate and compare patterns of cell surface antigen expression in familial CLL and sporadic CLL. The pattern of cell surface antigen expression was studied in familial and sporadic CLL to determine if unique identifiers of familial CLL could be detected. Survival in familial CLL verses sporadic CLL was compared and the association between prognosis and CD38 expression studied. Familial and sporadic CLL demonstrated the same characteristic immunophenotype (positive for surface immunoglobulin, CD5, CD19, and CD23 with dim CD20, and CD22). CD2 and CD13 expression, however, were more frequent (30% of cases) in familial CLL (P = 0.0003 for CD2, P = 0.006 for CD13) than in sporadic CLL (2-6%). There was no significant difference in survival in the two groups studied. Although the incidence of CD38 expression was similar in familial and sporadic CLL (47% and 44% respectively) the association with prognosis differed. There was a trend to decreased survival in CD38 positive sporadic (P = 0.06) but not familial CLL patients. We conclude that detection of CD2 or CD13 expression in CLL suggests familial CLL and examination of family history for additional affected members is warranted. Furthermore, CD38 expression does not carry the negative prognosis observed in sporadic CLL.

Survival Patterns among Chronic Lymphocytic Leukemia and Other Lymphoma Patients with Family History of Lymphoma.

Background. A role for genetic factors in chronic lymphocytic leukemia (CLL) is unequivocal based on evidence from multiply affected families, from case series, twin and case-control studies, and population-based registry studies. Similar characteristics have been observed for non-Hodgkin lymphoma (NHL) and Hodgkin lymphoma (HL). Population-based studies have found CLL, NHL and HL to co-occur in families. A few hospital-based series have explored survival outcomes in familial vs. sporadic CLL patients based on the hypothesis that genetic mechanisms involved in the causation of familial lymphomas might influence survival, however these have been based on small numbers with inconsistent findings. We have conducted a large study in Scandinavia including more than 41,000 lymphoma patients to quantify survival outcomes among familial vs. sporadic patients.Methods. We used the population-based central Cancer and Multigenerational Registries in Sweden and Denmark to identify all CLL (n=7749), NHL (n=25801), and HL (n=7476) patients diagnosed 1958–2001, with linkable first-degree relatives. All relatives were linked with the Cancer Registries to obtain information on CLL, NHL, and HL. Using Cox proportional hazard models, we calculated hazard ratios (HRs) and 95% confidence intervals (CIs) as measures of overall survival for CLL, NHL, and HL patients with vs. without family history of lymphoma.Results. We found 85 (1.1%) CLL, 207 (0.8%) NHL, and 96 (1.3%) HL patients with family history of lymphoma. Overall survival was similar for CLL (HR=1.24, 95% CI 0.93–1.67), NHL (HR=0.97, 95% CI 0.80–1.16), and HL (HR=0.78, 95% CI 0.51–1.19) patients with vs. without family history of lymphoma. Risk-estimates were similar when we calculated overall survival by age at lymphoma diagnosis (above vs. below median age), year at diagnosis (before vs. after 1987), and by sex. Consistent with the literature, including all CLL, NHL and HL patients, older age (p<0.001) and male gender (p<0.001) was associated with poorer survival. However, when analyses were restricted to patients with family history of lymphoma, only older age (p<0.005) remained significant.Conclusions: Survival patterns were similar for CLL, NHL, and HL patients with vs. without family history of lymphoma, suggesting that familial lymphomas do not have an altered clinical course. Overall, there is no evidence at this time to modify therapeutic strategies for patients with CLL, NHL, or HL based solely on family history.

Chronic Lymphocytic Leukemia: Keeping Cell Death at Bay

Chronic lymphocytic leukemia (CLL) is a common adult leukemia caused by abnormal accumulation of B cells. Raval et al. (2007) now implicate dowregulation of the expression of the kinase DAPK1 both genetically and epigenetically in familial and sporadic CLL.

Familial CLL: Genes and Environment

Families with multiple individuals affected with chronic lymphocytic leukemia (CLL) and other related B-cell tumors have been described in the literature. Familial CLL does not appear to differ from sporadic CLL in terms of prognostic markers and clinical outcome. While some environmental factors (such as farming-related exposures and occupational chemicals) may increase risk of CLL, results of epidemiologic studies have been generally inconsistent. Rates of CLL in the population show significant international variation, with the highest rates in the U.S. and Europe and the lowest rates in Asia. Migrants from Asia to the U.S. also have low rates of CLL, which supports a greater role for genetic compared with environmental risk factors. Large, population-based case-control and cohort studies have also shown significant familial aggregation of CLL and related conditions including non-Hodgkin and Hodgkin lymphoma. Monoclonal B-cell lymphocytosis also aggregates in families with CLL. However, the clinical implication of familial aggregation is minimal given the overall rarity of CLL. Linkage studies have been conducted in high-risk CLL families to screen the whole genome for loci that contribute to susceptibility, but no gene mutations have yet been identified by this method. Association studies of candidate genes have implicated immune function and other genes, but more studies are needed to verify these findings. The ability to conduct large-scale genomic studies will play an important role in detecting susceptibility genes for CLL over the next few years and thereby help to delineate etiologic pathways.