Analysis Of Exome Sequencing Data Research Articles

Discovery of a MET-driven monogenic cause of steatotic liver disease.

Metabolic dysfunction-associated steatotic liver disease (MASLD) affects about a third of adults worldwide and is projected soon to be the leading cause of cirrhosis. It occurs when fat accumulates in hepatocytes and can progress to metabolic dysfunction-associated steatohepatitis (MASH), liver cirrhosis, and hepatocellular carcinoma. MASLD pathogenesis is believed to involve a combination of genetic and environmental risk factors. Single nucleotide polymorphisms have been implicated but non-syndromic monogenic causes are lacking. We identified a novel genetic variant in a familial case of MASH and performed deep variant functional analysis including protein modeling, dynamics, and cell-based assays to assess molecular mechanisms of dysfunction and altered cellular signaling. We analyzed exome sequencing data of 3,904 individuals with steatotic liver disease (SLD) to identify additional cases and establish the link between specific gene variants and SLD diagnosis. We discovered and functionally validated the NM_000245.4:c.3505A>T; p.(Ile1169Phe) variant in the MET (mesenchymal epithelial transition) kinase domain as a monogenic cause of SLD. Subsequently, we detected additional ultra-rare, previously un-interpreted, and likely deleterious variants in MET from screening sequencing data. Among individuals with confirmed SLD based on electronic record review, 1.1% (45/3,904) had rare predicted deleterious MET variants. Eight of 45 (17.7%) individuals had predicted deleterious variants in the MET kinase domain confirmed to be functionally like the familial case variant. We report the first germline non-malignant rare MET-driven disease, a monogenic form of SLD.

Generation and characterization of two induced pluripotent stem cell lines (ICGi052-A and ICGi052-B) from a patient with frontotemporal dementia with parkinsonism-17 associated with the pathological variant c.2013T>G in the MAPT gene.

Frontotemporal dementia with parkinsonism-17 is a neurodegenerative disease characterised by pathological aggregation of the tau protein with the formation of neurofibrillary tangles and subsequent neuronal death. The inherited form of frontotemporal dementia can be caused by mutations in several genes, including the MAPT gene on chromosome 17, which encodes the tau protein. As there are currently no medically approved treatments for frontotemporal dementia, there is an urgent need for research using in vitro cell models to understand the molecular genetic mechanisms that lead to the development of the disease, to identify targets for therapeutic intervention and to test potential drugs to prevent neuronal death. Analysis of exome sequencing data from a 46-year-old patient with a clinical diagnosis of Parkinson's disease revealed the presence of the pathological variant c.2013T>G (rs63750756) in the MAPT gene, which is associated with frontotemporal dementia with parkinsonism-17. By reprogramming the patient's peripheral blood mononuclear cells, we obtained induced pluripotent stem cells (iPSCs). Two iPSC lines were characterised in detail. Reprogramming was performed by transfection with non-integrating episomal vectors expressing the OCT4, SOX2, KLF4, LIN28, L-MYC and mp53DD proteins. The iPSC lines ICGi052-A and ICGi052-B proliferate stably, form colonies with a morphology characteristic of human pluripotent cells, have a normal diploid karyotype (46,XX), express endogenous alkaline phosphatase and pluripotency markers (OCT4, NANOG, SSEA-4 and TRA-1-60) and are able to differentiate into derivatives of three germ layers: ento-, ecto- and mesoderm. The iPSC lines obtained and characterised in detail in this work represent a unique tool for studying the molecular genetic mechanisms of the pathogenesis of frontotemporal dementia with parkinsonism-17, as well as for testing potential drugs in vitro.

Comparison of Galaxy and Unix tools for analyzing the exome sequencing data from syndactyly abnormalities

Syndactyly is a congenital limb abnormality, which manifests as the fusion of digits due to incomplete separation during embryonic development, and its pathogenesis involves intricate genetic and molecular processes. Since Exome sequencing has gained widespread utilization as an invaluable tool for exploring genetic disorders during prenatal development, the Bioinformatic platforms, such as GALAXY and UNIX, play a central role in the analysis process of exome sequencing data, facilitating precise identification and interpretation of genetic variations linked to congenital abnormalities. In this study, we conducted a comparative analysis of exome sequencing data from a 1.5-year-old syndactyly patient using two platforms: GALAXY and UNIX. The UNIX platform identified a total of 275,572 variants, and the GALAXY platform identified 140,291 variants when compared with the Grch38/hg38 reference genome. A comparative analysis identified 126,848 common variants between the platforms. After filtration with the 200 syndactyly-related genes, 1,345 variants were remained. The distribution of these 1,345 variants spans the entirety of the patient's genome, with focal concentrations observed on specific chromosomes including chromosomes 2, 4, and 11. Concurrently, within the top 200 genes implicated in syndactyly, the genes FRAS1, CACNA1C, GLI2, and NOTCH1 exhibit the highest frequency of variants. These data emphasized the impact of the chosen analytical platform on genetic variation detection in congenital limb abnormalities, provided critical insights into the selection of bioinformatic tools for optimizing exome sequencing workflows in the context of limb malformations, contributed to advancements in genetic research and diagnostic methodologies.

Systematic Screening of Autosomal Dominant Tubulointerstitial Kidney Disease- MUC1 27dupC Pathogenic Variant through Exome Sequencing.

The MUC1 gene is associated with autosomal dominant tubulointerstitial kidney disease (ADTKD), leading to CKD. Current methods of sequencing, like exome sequencing, rarely detect MUC1 pathogenic variants because of the variable number of tandem repeats (VNTR) in MUC1 exon2. We demonstrated that combining fast read filtering with a sensitive VNTR genotyping strategy enables systematic screening of 27dupC pathogenic MUC1 variant from exome data. We initially validated our bioinformatics pipeline in a proof-of-concept cohort incorporating exome data from 33 participants with a known MUC1 pathogenic variant identified by Snapshot PCR and confirmed by 54 MUC1-negative individuals for negative control. We then retrospectively analyzed exome sequencing data from January 2019 to October 2023 from 3512 adult participants with nephropathy of unknown origin. Finally, we prospectively validated our pipeline in 825 additional participants enrolled from November 2023. SharkVNTyper accurately identified MUC1 variants in 32 out of 33 participants and excluded its presence in all the 54 negative controls in the proof-of-concept cohort (sensitivity of 97%, specificity of 100%). Integration of Shark tool with VNTyper significantly reduced running time from 6-12 hours to 5-10 minutes per sample, allowing both retrospective and prospective analysis. In the retrospective cohort, SharkVNTyper identified 23 additional positive cases that were not suspected clinically and had been missed in the initial exome analysis; 18 of these cases were confirmed as carrying the MUC1 27dupC mutation by low-throughput Snapshot PCR. In the prospective cohort of 825 CKD cases, systematic screening discovered 13 positive cases, with 12 confirmed by PCR. Overall, of 63 participants (1.4% of 4653) with molecularly confirmed ADTKD-MUC1, comprehensive diagnoses and descriptions of the disease were available for 24 participants. Median age of kidney failure was 50 years, 38% exhibited bilateral multiple kidney cysts, 8% had early-onset gout, and 58% had arterial hypertension. SharkVNTyper enables the analysis of highly repeated regions, such as the MUC1 VNTR, and facilitates the systematic screening of ADTKD-MUC1 from exome data, fostering 27dupC variation identification.

Rare exonic CELSR3 variants identified in Bladder Exstrophy Epispadias Complex.

Bladder exstrophy epispadias complex (BEEC) is a rare congenital anomaly of unknown etiology, although, genetic and environmental factors have been associated with its development. Variants in several genes expressed in the urogenital pathway have been reported as causative for bladder exstrophy in human and murine models. The expansion of next-generation sequencing and molecular genomics has improved our ability to identify the underlying genetic causes of similarly complex diseases and could thus assist with the investigation of the molecular basis of BEEC. The objective was to identify the presence of rare heterozygous variants in genes previously implicated in bladder exstrophy and correlate them with the presence or absence of bladder regeneration in our study population. We present a case series of 12 patients with BEEC who had bladder biopsies performed by pediatric urology during bladder neck reconstruction or bladder augmentation. Cases were classified as "sufficient" or "insufficient" (n = 5 and 7, respectively) based on a bladder volume of greater than or less than 40% of expected bladder size. Control bladder tissue specimens were obtained from patients (n = 6) undergoing biopsies for conditions other than bladder exstrophy. Whole exome sequencing was performed on DNA isolated from the bladder specimens. Based on the hypothesis of de novo mutations, as well as the potential implications of autosomal dominant conditions with incomplete penetrance, each case was evaluated for autosomal dominant variants in a set of genes previously implicated in BEEC. Our review of the literature identified 44 genes that have been implicated in human models of bladder exstrophy. Our whole exome sequencing data analysis identified rare variants in two of these genes among the cases classified as sufficient, and seven variants in five of these genes among the cases classified as insufficient. We identified rare variants in seven previously implicated genes in our BEEC specimens. Additional research is needed to further understand the cellular signaling underlying this potentially genetically heterogeneous embryological condition.

Core planar cell polarity genes VANGL1 and VANGL2 in predisposition to congenital vertebral malformations

Congenital scoliosis (CS), affecting approximately 0.5 to 1 in 1,000 live births, is commonly caused by congenital vertebral malformations (CVMs) arising from aberrant somitogenesis or somite differentiation. While Wnt/ß-catenin signaling has been implicated in somite development, the function of Wnt/planar cell polarity (Wnt/PCP) signaling in this process remains unclear. Here, we investigated the role of Vangl1 and Vangl2 in vertebral development and found that their deletion causes vertebral anomalies resembling human CVMs. Analysis of exome sequencing data from multiethnic CS patients revealed a number of rare and deleterious variants in VANGL1 and VANGL2, many of which exhibited loss-of-function and dominant-negative effects. Zebrafish models confirmed the pathogenicity of these variants. Furthermore, we found that Vangl1 knock-in (p.R258H) mice exhibited vertebral malformations in a Vangl gene dose- and environment-dependent manner. Our findings highlight critical roles for PCP signaling in vertebral development and predisposition to CVMs in CS patients, providing insights into the molecular mechanisms underlying this disorder.

Rare Deletions or Large Duplications Contribute to Genetic Variation in Patients with Severe Tinnitus and Meniere Disease.

Meniere disease (MD) is a debilitating disorder of the inner ear defined by sensorineural hearing loss (SNHL) associated with episodes of vertigo and tinnitus. Severe tinnitus, which occurs in around 1% of patients, is a multiallelic disorder associated with a burden of rare missense single nucleotide variants in synaptic genes. Rare structural variants (SVs) may also contribute to MD and severe tinnitus. In this study, we analyzed exome sequencing data from 310 MD Spanish patients and selected 75 patients with severe tinnitus based on a Tinnitus Handicap Inventory (THI) score > 68. Three rare deletions were identified in two unrelated individuals overlapping the ERBB3 gene in the positions: NC_000012.12:g.56100028_56100172del, NC_000012.12:g.56100243_56101058del, and NC_000012.12:g.56101359_56101526del. Moreover, an ultra-rare large duplication was found covering the AP4M1, COPS6, MCM7, TAF6, MIR106B, MIR25, and MIR93 genes in another two patients in the NC_000007.14:g.100089053_100112257dup region. All the coding genes exhibited expression in brain and inner ear tissues. These results confirm the contribution of large SVs to severe tinnitus in MD and pinpoint new candidate genes to get a better molecular understanding of the disease.

A novel splice-site FHOD3 founder variant is a common cause of hypertrophic cardiomyopathy in the population of the Balkans-A cohort study.

Founder variants in sarcomere protein genes account for a significant proportion of disease-causing variants in patients with hypertrophic cardiomyopathy (HCM). However, information on founder variants in non-sarcomeric protein genes, such as FHOD3, which have only recently been associated with HCM, remains scarce. In this study, we conducted a retrospective analysis of exome sequencing data of 134 probands with HCM for recurrent pathogenic variants. We discovered a novel likely pathogenic variant c.1646+2T>C in FHOD3 in heterozygous state in eight probands with HCM and confirmed its presence in seven additional relatives. Individuals with this variant had a wide range of ages at onset of the disease (4-63 years). No adverse cardiac events were observed. Haplotype analysis revealed that the individuals with this variant shared a genomic region of approximately 5 Mbp surrounding the variant, confirming the founder effect of the variant. FHOD3 c.1646+2T>C is estimated to have arisen 58 generations ago (95% CI: 45-81) in a common ancestor living on the Balkans. A founder FHOD3 c.1646+2T>C variant is the second most common genetic variant in our cohort of patients with HCM, occurring in 16% of probands with a known genetic cause of HCM, which represents a substantially higher proportion than the currently estimated 0.5-2% for causal FHOD3 variants. Our study broadens the understanding of the genetic causes of HCM and may improve the diagnosis of this condition, particularly in patients from the Balkans.

Mechanisms of pathogenicity and the quest for genetic modifiers of kidney disease in branchiootorenal syndrome.

Branchiootorenal (BOR) syndrome is an autosomal dominant disorder caused by pathogenic EYA1 variants and clinically characterized by auricular malformations with hearing loss, branchial arch anomalies, and congenital anomalies of the kidney and urinary tract. BOR phenotypes are highly variable and heterogenous. While random monoallelic expression is assumed to explain this phenotypic heterogeneity, the potential role of modifier genes has not yet been explored. Through thorough phenotyping and exome sequencing, we studied one family with disease presentation in at least four generations in both clinical and genetic terms. Functional investigation of the single associated EYA1 variant c.1698+1G>A included splice site analysis and assessment of EYA1 distribution in patient-derived fibroblasts. The candidate modifier gene CYP51A1 was evaluated by histopathological analysis of murine Cyp51+/- and Cyp51-/- kidneys. As the gene encodes the enzyme lanosterol 14α-demethylase, we assessed sterol intermediates in patient blood samples as well. The EYA1 variant c.1698+1G>A resulted in functional deletion of the EYA domain by exon skipping. The EYA domain mediates protein-protein interactions between EYA1 and co-regulators of transcription. EYA1 abundance was reduced in the nuclear compartment of patient-derived fibroblasts, suggesting impaired nuclear translocation of these protein complexes. Within the affected family, renal phenotypes spanned from normal kidney function in adulthood to chronic kidney failure in infancy. By analyzing exome sequencing data for variants that potentially play roles as genetic modifiers, we identified a canonical splice site alteration in CYP51A1 as the strongest candidate variant. In this study, we demonstrate pathogenicity of EYA1 c.1698+1G>A, propose a mechanism for dysfunction of mutant EYA1, and conjecture CYP51A1 as a potential genetic modifier of renal involvement in BOR syndrome.

CYP19A1 mediates severe SARS-CoV-2 disease outcome in males

Male sex represents one of the major risk factors for severe COVID-19 outcome. However, underlying mechanisms that mediate sex-dependent disease outcome are as yet unknown. Here, we identify the CYP19A1 gene encoding for the testosterone-to-estradiol metabolizing enzyme CYP19A1 (also known as aromatase) as a host factor that contributes to worsened disease outcome in SARS-CoV-2-infected males. We analyzed exome sequencing data obtained from a human COVID-19 cohort (n= 2,866) using a machine-learning approach and identify a CYP19A1-activity-increasing mutation to be associated with the development of severe disease in men but not women. We further analyzed human autopsy-derived lungs (n= 86) and detect increased pulmonary CYP19A1 expression at the time point of death in men compared with women. In the golden hamster model, we show that SARS-CoV-2 infection causes increased CYP19A1 expression in the lung that is associated with dysregulated plasma sex hormone levels and reduced long-term pulmonary function in males but not females. Treatment of SARS-CoV-2-infected hamsters with a clinically approved CYP19A1 inhibitor (letrozole) improves impaired lung function and supports recovery of imbalanced sex hormones specifically in males. Our study identifies CYP19A1 as a contributor to sex-specific SARS-CoV-2 disease outcome in males. Furthermore, inhibition of CYP19A1 by the clinically approved drug letrozole may furnish a new therapeutic strategy for individualized patient management and treatment.

Integrating somatic CNV and gene expression in breast cancers from women with PTEN hamartoma tumor syndrome

Women with germline PTEN variants (PTEN hamartoma tumor syndrome, PHTS) have up to 85% lifetime risk of female breast cancer (BC). We previously showed that PHTS-derived BCs are distinct from sporadic BCs both at the clinical and genomic levels. In this study, we examined somatic copy number variations (CNV) and transcriptome data to further characterize the somatic landscape of PHTS-derived BCs. We analyzed exome sequencing data from 44 BCs from women with PHTS for CNV. The control group comprised of 558 women with sporadic BCs from The Cancer Genome Atlas (TCGA) dataset. Here, we found that PHTS-derived BCs have several distinct CNV peaks compared to TCGA. Furthermore, RNA sequencing data revealed that PHTS-derived BCs have a distinct immunologic cell type signature, which points toward cancer immune evasion. Transcriptomic data also revealed PHTS-derived BCs with pathogenic germline PTEN variants appear to have vitamin E degradation as a key pathway associated with tumorigenesis. In conclusion, our study revealed distinct CNV x transcript features in PHTS-derived BCs, which further facilitate understanding of BC biology arising in the setting of germline PTEN mutations.

Evaluation of Type 2 Diabetes Risk Variants (Alleles) in the Pashtun Ethnic Population of Pakistan.

To evaluate the Type 2 Diabetes (T2D) risk variants in the Pashtun ethnic population of Khyber Pakhtunkhwa using nascent whole-exome sequencing (WES) to better understand the pathogenesis of this complex polygenic disorder. A total of 100 confirmed patients with T2D of Pashtun ethnicity were included in the study, DNA was extracted from whole blood samples, and paired-end libraries were prepared using the Illumina Nextera XT DNA library kit carefully following the manufacturer's instructions. Illumina HiSeq 2000 was used to obtain sequences of the prepared libraries followed by bioinformatics data analysis. A total of n=11 pathogenic/likely pathogenic variants were reported in the CAP10, PAX4, IRS-2, NEUROD1, CDKL1 and WFS1. Among the reported variants CAP10/rs55878652 (c.1990-7T>C; p.Leu446Pro) and CAP10/rs2975766 (c.1996A>G; p.Ile666Val) identified were novel, and have not yet been reported for any disease in the database.The variants CAP10/rs7607759 (c.1510A>G, p.Thr504Ala), PAX4/rs712701 (c.962A>C; p.His321Pro), PAX4/rs772936097 (c.748-3delT; p.Arg325Trp), IRS-2/rs1805097 (c.3170G>A; p.Gly1057Asp), NEUROD1/rs1801262 (c.133A>G; p.Thr45Ala), CDKL1/rs77152992 (c.1226C>T; p.Pro409Leu), WFS1/rs1801212 (c.997G>A; p.Val333Ile), WFS1/rs1801208 (c.1367G>A; p.Arg456His), and WFS1/rs734312 (c.1832G>A; p.Arg611His) are previously identified in other ethnic populations. Our study reconfirms the associations of these variants with T2D in the Pakistani Pashtun population. In-silico analysis of exome sequencing data suggests a statistically substantial association of all (n=11) identified variants with T2D in the Pashtun ethnic population. This study may serve as a foundation for performing future molecular studies aimed at unraveling T2D associated genes.

Unique Haplotypes in OPN1LW as a Common Cause of High Myopia With or Without Protanopia: A Potential Window Into Myopic Mechanism.

Specific haplotypes (LVAVA, LIVVA, and LIAVA) formed by five polymorphisms (p.L153M, p.V171I, p.A174V, p.I178V, and p.S180A in exon 3 of OPN1LW) that cause partial or complete exon skipping have been reported as unique genetic causes of high myopia with or without colorblindness. This study aimed to identify the contribution of OPN1LW to early-onset high myopia (eoHM) and the molecular basis underlying eoHM with or without colorblindness. Comparative analysis of exome sequencing data was conducted for 1226 families with eoHM and 9304 families with other eye conditions. OPN1LW variants detected by targeted or whole exome sequencing were confirmed by long-range amplification and Sanger sequencing, together with segregation analysis. The clinical data were thoroughly analyzed. Unique haplotypes and truncation variants in OPN1LW were detected exclusively in 68 of 1226 families with eoHM but in none of the 9304 families with other visual diseases (P = 1.63 × 10-63). Four classes of variants were identified: haplotypes causing partial splicing defects in OPN1LW (LVAVA or LIVVA in 31 families), LVAVA in OPN1LW-OPN1MW hybrid gene (in 3 families), LIAVA in OPN1LW (in 29 families), and truncations in OPN1LW (in 5 families). The first class causes partial loss of red photopigments, whereas the latter three result in complete loss of red photopigments. This is different from the replacement of red with green owing to unequal re-arrangement causing red-green colorblindness alone. Of the 68 families, 42 affected male patients (31 families) with the first class of variants (LVAVA or LIVVA in OPN1LW) had eoHM alone, whereas 37 male patients with the latter 3 classes had eoHM with protanopia. Adaptive optics retinal imaging demonstrated reduced cone regularity and density in men with eoHM caused by OPN1LW variants compared to those patients with eoHM and without OPN1LW variants. Based on the 68 families with unique variants in OPN1LW, our study provides firm evidence that the two different phenotypes (eoHM with or without colorblindness) are caused by two different classes of variants (partial splicing-effect haplotypes or complete splicing-effect haplotypes/truncation variants, respectively). The contribution of OPN1LW to eoHM (isolated and syndromic) was characterized by OPN1LW variants found in 5.5% (68/1226) of the eoHM families, making it the second most common cause of monogenic eoHM alone (2.4%) and a frequent cause of syndromic monogenic eoHM with colorblindness. Such haplotypes, in which each individual variant alone is considered a benign polymorphism, are potential candidates for other hereditary diseases with causes of missing genetic defects.

De novo variants implicate chromatin modification, transcriptional regulation, and retinoic acid signaling in syndromic craniosynostosis

Craniosynostosis (CS) is the most common congenital cranial anomaly. Several Mendelian forms of syndromic CS are well described, but a genetic etiology remains elusive in a substantial fraction of probands. Analysis of exome sequence data from 526 proband-parent trios with syndromic CS identified a marked excess (observed 98, expected 33, p= 4.83×10-20) of damaging de novo variants (DNVs) in genes highly intolerant to loss-of-function variation (probability of LoF intolerance>0.9). 30 probands harbored damaging DNVs in 21 genes that were not previously implicated in CS but are involved in chromatin modification and remodeling (4.7-fold enrichment, p= 1.1×10-11). 17 genes had multiple damaging DNVs, and 13 genes (CDK13, NFIX, ADNP, KMT5B, SON, ARID1B, CASK, CHD7, MED13L, PSMD12, POLR2A, CHD3, and SETBP1) surpassed thresholds for genome-wide significance. A recurrent gain-of-function DNV in the retinoic acid receptor alpha (RARA; c.865G>A [p.Gly289Arg]) was identified in two probands with similar CS phenotypes. CS risk genes overlap with those identified for autism and other neurodevelopmental disorders, are highly expressed in cranial neural crest cells, and converge in networks that regulate chromatin modification, gene transcription, and osteoblast differentiation. Our results identify several CS loci and have major implications for genetic testing and counseling.

Abstract 1515: Tumor molecular profiling and spatial transcriptomics to assess colorectal cancer heterogeneity and microenvironment

Abstract Introduction: CRC is the second leading cause of cancer mortality in the United States. Clinical factors and molecular characteristics may impact therapeutics and prognosis. Scientific studies have uncovered significant aberrations, including critical genes and pathways. Despite these efforts, few studies have utilized similar sample sizes to TCGA, heterogeneous populations and integrative clinical data to compare their reported genomic changes, even though little is known about the tumor microenvironment and its significance for colorectal tumorigenesis. Methods: Clinical and DNA genomic data from 262 colorectal tumor/normal DNA samples were obtained for whole exome sequencing analysis from the Oncology Research Information Exchange Network and two colorectal tissue samples for Spatial Transcriptomics profiling from the USC colorectal cancer Moonshot project. Whole Exome Sequencing data analysis was used for identifying genetic alterations. Samples were stratified based on microsatellite instability, age group, anatomical subsites, and histological subtypes. Emphasis was given to comparing molecular characteristics among Hispanic/Latino patients since their reported higher mortality and cancer disparities. Mutation frequencies from our cohort were compared to those from the TCGA. An ongoing spatial transcriptomics analysis consists in processing two fresh-frozen tissue samples through the visium spatial gene expression library using standard short-read sequencing. Results: Tumor molecular profiling revealed 20 genes significantly mutated. We found differences in gene mutation frequencies among our samples, highlighting APC (60%), TP53 (56%), TTN (49%), and KRAS (44%) gene mutations. In comparison with TCGA data, in addition to the expected APC, TP53, PIK3CA, and KRAS mutations, we found frequent mutations in POLE and TTN. To assess the basis for the considerably different mutation rates, we evaluated MSI. Among the 262 tumors, 41 (16%) had high levels of MSI, 2 (1%) had low levels of MSI (MSI-L), and 215 (82%) were microsatellite stable (MSS). Cancer heterogeneity was reported among tumors with different characteristics such as age group, anatomical subsite, and histological subtypes. The ongoing spatial transcriptomics analysis that will be ready before the annual meeting will identify cellular populations and map immunological and inflammatory signals in the microenvironment. Conclusions: Our study reveals the impact of molecularly profiling tumors using considerable sample sizes and stratified samples in several subgroups. Our study adds important information about tumor heterogeneity and the tumor microenvironment in colorectal cancer by including our spatial transcriptomics data analysis. Citation Format: Enrique Velazquez Villarreal, Seeta Rajpara, Yuxin Jin, Jing Qian, Bohan Zhang, Brigette Waldrup, Donna Loza, Heinz-Josef Lenz, David W. Craig, John D. Carpten. Tumor molecular profiling and spatial transcriptomics to assess colorectal cancer heterogeneity and microenvironment [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 1515.

Extended analysis of exome sequencing data reveals a novel homozygous deletion of exons 3 and 4 in FUCA1 gene causing fucosidosis in an Indian family.

do Rosario, Michelle C.a; Purushothama, Greeshmaa; Narayanan, Dhanya Lakshmia,b; Siddiqui, Shahyanc; Girisha, Katta Mohana; Shukla, Anjua Author Information

Homozygous Missense Variant in the Solute Carrier Organic Anion Transporter 2A1 (SLCO2A1) Gene Underlies Isolated Nail Clubbing.

Inherited isolated nail clubbing is a very rare Mendelian condition in humans, characterized by enlargement of the terminal segments of fingers and toes with thickened nails. Mutations in two genes have been reported to cause isolated nail clubbing in humans, which are the SLCO2A1 gene and the HPGD gene. An extended Pakistani family having two affected siblings born of unaffected consanguineous union was included in the study. Predominant isolated congenital nail clubbing (ICNC) without any other systemic abnormalities was observed, which we aimed to characterize at clinico-genetic level. Whole exome coupled with Sanger sequencing were employed to uncover the sequence variant as a cause of the disease. Furthermore, protein modeling was carried out to reveal the predicted possible effect of the mutation at the protein level. Whole exome sequencing data analysis revealed a novel biallelic sequence variant (c.155T>A; p.Phe52Tyr) in the SLCO2A1 gene. Further, Sanger sequencing analysis validated and confirmed the segregation of the novel variant in the entire family. Subsequently, protein modeling of the wild-type and mutated SLCO2A1 revealed broad-scale change, which might compromise the proteins' secondary structure and function. The present study adds another mutation to the SLCO2A1-related pathophysiology. The involvement of SLCO2A1 in the pathogenesis of ICNC may open exciting perceptions of this gene in nail development/morphogenesis.

Exome sequencing reveals a distinct somatic genomic landscape in breast cancer from women with germline PTEN variants

Germline PTEN variants (PTEN hamartoma tumor syndrome [PHTS]) confer up to 85% lifetime risk of female breast cancer (BC). BCs arising in PHTS are clinically distinct from sporadic BCs, including younger age of onset, multifocality, and an increased risk of second primary BCs. Yet, there is no previous investigation into the underlying genomic landscape of this entity. We sought to address the hypothesis that BCs arising in PHTS have a distinct genomic landscape compared to sporadic counterparts. We performed and analyzed exome sequencing data from 44 women with germline PTEN variants who developed BCs. The control cohort comprised of 497 women with sporadic BCs from The Cancer Genome Atlas (TCGA) dataset. We demonstrate that PHTS-derived BCs have a distinct somatic mutational landscape compared to the sporadic counterparts, namely second somatic hits in PTEN, distinct mutational signatures, and increased genomic instability. The PHTS group had a significantly higher frequency of somatic PTEN variants compared to TCGA (22.7% versus 5.6%; odds ratio [OR] 4.93; 95% confidence interval [CI] 2.21 to 10.98; p<0.001) and a lower mutational frequency in PIK3CA (22.7% versus 33.4%; OR 0.59; 95% CI 0.28 to 1.22; p= 0.15). Somatic variants in PTEN and PIK3CA were mutually exclusive in PHTS (p= 0.01) but not in TCGA. Our findings have important implications for the personalized management of PTEN-related BCs, especially in the context of more accessible genetic testing.

Association of Common and Rare Genetic Variation in the 3-Hydroxy-3-Methylglutaryl Coenzyme A Reductase Gene and Cataract Risk.

BackgroundResults from animal models and observational studies have raised concerns regarding the potential cataractogenic effects of statin treatment. We investigated whether common and rare genetic variants in HMGCR are associated with cataract risk, to gauge the likely long‐term effects of statin treatment on lenticular opacities.Methods and ResultsWe used genotyping data and exome sequencing data of unrelated European individuals in the UK Biobank to test the association between genetically proxied inhibition of HMGCR and cataract risk. First, we constructed an HMGCR genetic score consisting of 5 common variants weighted by their association with low‐density lipoprotein cholesterol. Second, we analyzed exome sequencing data to identify carriers of predicted loss‐of‐function mutations in HMGCR. Common and rare variants in aggregate were then tested for association with cataract and cataract surgery. In an analysis of >402 000 individuals, a 38.7 mg/dL (1 mmol/L) reduction in low‐density lipoprotein C by the HMGCR genetic score was associated with higher risk for cataract (odds ratio, 1.14 [95% CI, 1.00–1.39], P=0.045) and cataract surgery (odds ratio, 1.25 [95% CI, 1.06–1.48], P=0.009). Among 169 172 individuals with HMGCR sequencing data, we identified 32 participants (0.02%), who carried a rare HMGCR predicted loss‐of‐function variant. Compared with noncarriers, heterozygous carriers of HMGCR predicted loss‐of‐function had a higher risk of developing cataract (odds ratio, 4.54 [95% CI, 1.96–10.53], P=0.001) and cataract surgery (odds ratio, 5.27 [95% CI, 2.27–12.25], P=5.37×10−4). In exploratory analyses, we found no significant association between genetically proxied inhibition of PCSK9, NPC1L1, or circulating low‐density lipoprotein cholesterol levels (P>0.05 for all) and cataract risk.ConclusionsWe found that genetically proxied inhibition of the HMGCR gene mimicking long‐term statin treatment associated with higher risk of cataract. Clinical trials with longer follow‐up are needed to confirm these findings.

Exome Sequencing Data Analysis and a Case-Control Study in Mexican Population Reveals Lipid Trait Associations of New and Known Genetic Variants in Dyslipidemia-Associated Loci.

Background: Plasma lipid levels are a major risk factor for cardiovascular diseases. Although international efforts have identified a group of loci associated with the risk of dyslipidemia, Latin American populations have been underrepresented in these studies. Objective: To know the genetic variation occurring in lipid-related loci in the Mexican population and its association with dyslipidemia. Methods: We searched for single-nucleotide variants in 177 lipid candidate genes using previously published exome sequencing data from 2838 Mexican individuals belonging to three different cohorts. With the extracted variants, we performed a case-control study. Logistic regression and quantitative trait analyses were implemented in PLINK software. We used an LD pruning using a 50-kb sliding window size, a 5-kb window step size and a r2 threshold of 0.1. Results: Among the 34251 biallelic variants identified in our sample population, 33% showed low frequency. For case-control study, we selected 2521 variants based on a minor allele frequency ≥1% in all datasets. We found 19 variants in 9 genes significantly associated with at least one lipid trait, with the most significant associations found in the APOA1/C3/A4/A5-ZPR1-BUD13 gene cluster on chromosome 11. Notably, all 11 variants associated with hypertriglyceridemia were within this cluster; whereas variants associated with hypercholesterolemia were located at chromosome 2 and 19, and for low high density lipoprotein cholesterol were in chromosomes 9, 11, and 19. No significant associated variants were found for low density lipoprotein. We found several novel variants associated with different lipemic traits: rs3825041 in BUD13 with hypertriglyceridemia, rs7252453 in CILP2 with decreased risk to hypercholesterolemia and rs11076176 in CETP with increased risk to low high density lipoprotein cholesterol. Conclusions: We identified novel variants in lipid-regulation candidate genes in the Mexican population, an underrepresented population in genomic studies, demonstrating the necessity of more genomic studies on multi-ethnic populations to gain a deeper understanding of the genetic structure of the lipemic traits.