Type Of Copy Number Variation Research Articles

Systematic molecular analyses for 115 karyotypically normal men with isolated non-obstructive azoospermia.

Do copy-number variations (CNVs) in the azoospermia factor (AZF) regions and monogenic mutations play a major role in the development of isolated (non-syndromic) non-obstructive azoospermia (NOA) in Japanese men with a normal 46, XY karyotype? Deleterious CNVs in the AZF regions and damaging sequence variants in eight genes likely constitute at least 8% and approximately 8% of the genetic causes, respectively, while variants in other genes play only a minor role. Sex chromosomal abnormalities, AZF-linked microdeletions, and monogenic mutations have been implicated in isolated NOA. More than 160 genes have been reported as causative/susceptibility/candidate genes for NOA. Systematic molecular analyses were conducted for 115 patients with isolated NOA and a normal 46, XY karyotype, who visited our hospital between 2017 and 2021. We studied 115 unrelated Japanese patients. AZF-linked CNVs were examined using sequence-tagged PCR and multiplex ligation-dependent probe amplification, and nucleotide variants were screened using whole exome sequencing (WES). An optimized sequence kernel association test (SKAT-O), a gene-based association study using WES data, was performed to identify novel disease-associated genes in the genome. The results were compared to those of previous studies and our in-house control data. Thirteen types of AZF-linked CNVs, including the hitherto unreported gr/gr triplication and partial AZFb deletion, were identified in 63 (54.8%) cases. When the gr/gr deletion, a common polymorphism in Japan, was excluded from data analyses, the total frequency of CNVs was 23/75 (30.7%). This frequency is higher than that of the reference data in Japan and China (11.1% and 14.7%, respectively). Known NOA-causative AZF-linked CNVs were found in nine (7.8%) cases. Rare damaging variants in known causative genes (DMRT1, PLK4, SYCP2, TEX11, and USP26) and hemizygous/multiple-heterozygous damaging variants in known spermatogenesis-associated genes (TAF7L, DNAH2, and DNAH17) were identified in nine cases (7.8% in total). Some patients carried rare damaging variants in multiple genes. SKAT-O detected no genes whose rare damaging variants were significantly accumulated in the patient group. The number of participants was relatively small, and the clinical information of each patient was fragmentary. Moreover, the pathogenicity of identified variants was assessed only by in silico analyses. This study showed that various AZF-linked CNVs are present in more than half of Japanese NOA patients. These results broadened the structural variations of AZF-linked CNVs, which should be considered for the molecular diagnosis of spermatogenic failure. Furthermore, the results of this study highlight the etiological heterogeneity and possible oligogenicity of isolated NOA. This study was supported by Grants from the Japan Society for the Promotion of Science (21K19283 and 21H0246), the Japan Agency for Medical Research and Development (22ek0109464h0003), the National Center for Child Health and Development, the Canon Foundation, the Japan Endocrine Society, and the Takeda Science Foundation. The results of this study were based on samples and patient data obtained from the International Center for Reproductive Medicine, Dokkyo Medical University Saitama Medical Center, Koshigaya, Japan. The authors have no conflicts of interest to disclose. N/A.

Description of Copy Number Variations in a Series of Children and Adolescents with FASD in Reunion Island.

Fetal Alcohol Spectrum Disorders (FASD) are the most common cause of neurocognitive impairment and social inadaptation, affecting 1 birth in 100. Despite the existence of precise diagnostic criteria, the diagnosis remains difficult, often confounded with other genetic syndromes or neurodevelopmental disorders. Since 2016, Reunion Island has been a pilot region for the identification, diagnosis, and care of FASD in France. To evaluate the prevalence and the types of Copy Number Variations (CNV) in FASD patients. A retrospective chart review of 101 patients diagnosed with FASD in the Reference Center for developmental anomalies and in the FASD Diagnostic Center of the University Hospital was performed. Records of all patients were reviewed to obtain their medical history, family history, clinical phenotype, and investigations, including genetic testing (CGH- or SNP-array). A rate of 20.8% (n = 21) of CNVs was found including 57% (12/21) of pathogenic variants and 29% (6/21) of variants of uncertain signification (VUS). A particularly high number of CNVs was found in children and adolescents with FASD. It reinforces the plea for a multidisciplinary approach for developmental disorders to explore both environmental factors, such as avoidable teratogens and intrinsic vulnerabilities, especially genetic determinants.

Mutation spectrum and frequency of copy number variations of the ANOS1 gene in patients with Kallmann syndrome or normosmic isolated hypogonadotropic hypogonadism.

This study was performed to investigate the molecular characteristics and frequency of copy number variations (CNVs) of ANOS1 in patients with Kallmann syndrome (KS) or normosmic isolated hypogonadotropic hypogonadism (nIHH) using multiplex ligation-dependent probe amplification (MLPA) analysis and sequencing. Among 45 patients from 43 independent families, Sanger sequencing, next-generation sequencing (NGS), or microarray was performed in 24 patients from 23 families, and MLPA was performed in 19 patients who did not show rare sequence variants (n = 18) or ANOS1 amplification by PCR (n = 1). Seven patients (4 patients with KS, 1 patient with nIHH, one prepubertal boy with anosmia, and one newborn patient) from 6 families (6/43, 14%) harbored molecular defects in ANOS1 including a nonsense mutation [c.1140G>A (p.W380*)], a frameshift mutation [c.1260del (p.Q421Kfs*61)], a splice site mutation (c.1449+1G>A), an exon 7 deletion, a complete deletion, and 7.9 Mb-sized inversion encompassing ANOS1. The complete deletion of ANOS1 was identified in a neonate with a micropenis and cryptorchidism. Unilateral renal agenesis was found in three patients, whereas only one patient displayed both synkinesia and sensorineural hearing loss. There was no reversal of hypogonadotropic hypogonadism in any patient during 9.1 ± 2.9 years of treatment with testosterone enanthate. Molecular defects in the ANOS1 gene could be identified in 14% of probands including various types of CNVs (3/43, 7.0%). Comprehensive analysis using sequencing and analysis for CNVs is required to detect molecular defects in ANOS1.

Goat MyoD1: mRNA expression, InDel and CNV detection and their associations with growth traits

The Myogenic differentiation 1 (MyoD1) gene is a crucial regulator of muscle formation and differentiation. However, there are few studies on the mRNA expression pattern of the goat MyoD1 gene and its effect on goat growth and development. To address this, we investigated the mRNA expression of the MyoD1 gene in several tissues of fetal and adult goats, containing heart, liver, spleen, lung, kidney and skeletal muscle. The results focused on the expression of the MyoD1 gene in skeletal muscle of fetal goats was much higher than adult goats, suggesting its important role in skeletal muscle formation and development. Following, a total of 619 Shaanbei White Cashmere goats (SBWCs) were used to monitor the InDel (Insertion/Deletion) and CNV (Copy Number Variation) variations of the MyoD1 gene. Three InDel loci were identified, and there was no significant correlation with goat growth traits. Furthermore, a CNV locus containing the MyoD1 gene exon with three types (Loss type, Normal type, Gain type) were identified. The association analysis results showed that the CNV locus was significantly associated with body weight, height at hip cross, heart girth and hip width in SBWCs (P < 0.05). Meanwhile, the Gain type of CNV exhibited the best growth traits and good consistency among three types in goats, suggesting its potential as a DNA marker for marker-assisted breeding of goats. Overall, our study provided a scientific basis for breeding goats with better growth and development traits.

STK11 Causative Variants and Copy Number Variations Identified in Thai Patients With Peutz-Jeghers Syndrome.

Introduction Peutz-Jeghers syndrome (PJS) is a rare autosomal dominant inherited disorder caused by germline mutations in the serine-threonine kinase 11 (STK11) tumor suppressor gene. This syndrome is characterized by hamartomatous gastrointestinal polyps, mucocutaneous melanin pigmentation, and a higher risk of developing various cancers. Methods We summarized the clinical and molecular characteristics of five unrelated Thai patients with PJS. Denaturing high-performance liquid chromatography (DHPLC) screening, coupled with direct DNA sequencing and multiplex ligation-dependent probe amplification (MLPA), were applied for the molecular analysis of STK11. Results A total of four STK11 pathogenic changeswere identified in the five PJS patients, including two frameshift variants (a novel c.199dup, p.Leu67ProfsTer96 and a known c.834_835del, p.Cys278TrpfsTer6) and two types of copy number variations (CNV), exon 1 deletion and exons 2-3 deletion. Among reported STK11 exonic deletions, exon 1 and exons 2-3 deletions were found to be the two most commonly deleted exons. Conclusion All identified STK11 mutations were null mutations that were associated with more severe PJS phenotypes and cancers. This study broadens the phenotypic and mutational spectrum of STK11 in PJS.

Copy Number Variation of the SOX6 Gene and Its Associations with Growth Traits in Ashidan Yak.

Copy number variation (CNV) is a fundamental type of structural variation of the genome affecting the economic traits of livestock. The SOX6 gene (sex-determining region Y-box 6), as a transcription factor, has multiple functions with regard to sex determination, embryonic growth, the nervous system development, as well as bone, and various organ formation. This study employed quantitative real-time fluorescence quota PCR (qPCR) for detecting the SOX6-CNV of the 311 Ashidan yaks and analyzed the correlation of the SOX6-CNV with four phenotypes (including body weight, withers height, body length, and chest girth) of the yaks aged 6, 12, 18, and 30 months using ANOVA and multiple comparisons. Furthermore, the SOX6 gene expression was identified in seven different tissues of the yaks. The experiment results demonstrated the expression of SOX6 in each tissue, and the kidney and muscle tissue were found to have higher relative expression levels. Based on the processing by IBM SPSS software, SOX6-CNV was significantly correlated with the chest girth of the 6-months old yaks (p &lt; 0.05) and 30-months yaks (p &lt; 0.05), and withers height of 6 months yaks (p &lt; 0.05) and 18-months yaks (p &lt; 0.05), as well as the normal type of CNV, was chosen for yak breeding. In conclusion, SOX6 might be prominently involved in promoting growth and development of yaks, suggesting that the SOX6 gene can be used in breeding yaks by molecular marker-assisted selection (MAS). The study also offered some important insights into the references and clues for the genetic breeding of yaks.

Copy number variation of bovine S100A7 as a positional candidate affected body measurements

Beef production is closely related to the national economy and the attention has been paid to the improvement of beef cattle by molecular markers associated. Copy number variations (CNVs) recently have been gained many researches and recognized as an important source of genetic variation. Extensive studies have indicated that CNVs have effects on a large range of economic traits by a wide range of gene copy number alteration. S100A7 is a member of S100 family which is a famous family of Ca2+-binding proteins. S100A7 plays a crucial role in many important phenotypes (progress) including inflammatory diseases, psoriasis, obesity, etc. The aim of our study was to explore the phenotypic effects of CNV located in the S100A7 gene of bovine chromosome 3. We detected S100A7 CNV by qPCR in different cattle breeds, including Qinchuan cattle, Yunling cattle, Xianan cattle and a crossbred group Pinan. The copy number was identified as gain, normal and loss type, our results showed that the gain type was the main type in three types of S100A7 CNV of the whole tested breeds. After CNV detection, association analysis between S100A7 CNV and growth traits was carried out in four cattle breeds. We found significant effects of the CNV on cattle growth traits with differently preferred CNV types such as gain type with better chest depth (p = 0.043) in QC, loss type with better body length (p = 0.008) and rump width (p = 0.014) in YL, normal with better chest girth (p = 0.001), gain with better waist width (p = 0.001) and rump width (p = 0.044) in PN. These results suggested that the S100A7 CNV could affect the phenotypic traits and be used as a promising genetic marker for cattle molecular breeding.

Association between copy number variation of SERPINA3-1 gene and growth traits in Chinese cattle

Serpin peptidase inhibitor, clade A (alpha-1 antiproteinase, antitrypsin), member 3 (SERPINA3) belongs to the serine protease inhibitor family A subtype, and contains 8 genes from SERPINA3-1 to SERPINA3-8. Although the regulatory effects of these 8 genes have been revealed one by one in recent years, the related effects of SERPINA3-1 gene on cattle growth is still unclear. This study used quantitative Real time PCR (qPCR) to detect the type of copy number variation (CNV) of SERPINA3-1 gene in a total of 542 Chinese cattle, and expression of SERPINA3-1 gene in different tissues of Qinchuan cattles (adult) on mRNA level. Then association analysis was conducted between the detection results and cattle growth traits. The results showed that the Duplication type in SERPINA3-1 gene performed better on the growth traits and the CNV was significantly correlated with multiple growth traits (p < 0.05). In addition, SERPINA3-1 gene has different expression conditions in different tissues, results showed that SERPINA3-1 gene has a low expression in muscle. In conclusion, we speculate that the SERPINA3-1 gene can be used as a molecular marker and the result of this study could be a basic material for candidate functional genes for beef cattle growth and development.

Structural and numerical Y chromosomal variations in elderly men identified through multiplex ligation-dependent probe amplification.

Human Y chromosomes frequently acquire structural and numerical alterations. Known alterations include germline copy-number variations (CNVs) in the azoospermia factor (AZF) region and somatic mosaic loss of the Y chromosome (mLOY). Here, we explored Y chromosomal variations in 160 Japanese men aged 75-90 years. Multiplex ligation-dependent probe amplification (MLPA) identified ten types of AZF-linked CNVs in 77 men and mLOY of various degrees in 37. Seventeen men carried both a CNV and mLOY. MLOY levels estimated by MLPA were closely correlated with those determined by droplet digital PCR. No association was found between AZF-linked CNVs and the frequency or levels of mLOY. These results emphasize the high frequency and large inter-individual variability of AZF-linked CNVs and mLOY, and demonstrate the usefulness of MLPA in the detection of these variations. More importantly, this study provides the first evidence that AZF-linked CNVs do not increase the risk of aging-related mLOY.

A molecular marker of milk composition traits in NCAM2 gene of Chinese Holstein

The aim of this study was to detect the novel copy number variation (CNV) locus of NCAM2 gene in Chinese Holstein, and to analyze the effect of the novel CNV locus in NCAM2 gene on milk composition traits. The novel CNV locus of NCAM2 gene in 310 Chinese Holstein was detected by real-time quantitative fluorescent PCR (qPCR) and association analysis was performed between the novel CNV locus in NCAM2 gene and milk composition traits in Chinese Holstein. There are three CNV types of NCAM2 gene in Chinese Holstein: gain (increased copy number), median (normal copy number) and loss (deleted copy number). Statistical analysis revealed that there was a significant association between CNV types and milk fat rate (p < 0.05). Moreover, we also discovered that the milk production and milk protein rate of gain type is higher than that of loss type, but that of mediate type is lower than that of loss type. However, in terms of somatic cell score, loss type is higher than that of gain type, but that of mediate type is lower than that of gain type. These observations suggested that gain type can be used as a candidate molecular genetic marker of milk fat rate. Highlights The CNVs of the NCAM2 gene were detected and validated in Chinese Holstein. The type of CNV was successfully implemented using qPCR. The statistical analysis indicated that the CNV of the NCAM2 gene are significantly associated with milk fat rate.

Алгоритм интерпретации клинической значимости хромосомных микродупликаций при недифференцированных формах интеллектуальных расстройств

Идентификация хромосомных аномалий на субмикроскопическом уровне и установление их роли в этиологии интеллектуальных расстройств являются важной научной и практической задачей. Оценка патогенного значения менее изученного типа вариаций копийности ДНК - хромосомных микродупликаций представляет актуальный предмет для обсуждения. В исследовании предложен алгоритм интерпретации клинической значимости частичных трисомий, который является неотъемлемой составляющей в диагностике и профилактике хромосомных болезней. The identification of chromosomal abnormalities at the submicroscopic level and the establishment of their role in the etiology of intellectual disorders are an important scientific and practical task. Evaluation of the pathogenic value of the less studied type of copy number variation - chromosomal microduplication - is an actual issue. The study proposed an algorithm for interpreting the clinical significance of partial trisomies, which is an integral component in the diagnosis and prevention of chromosomal diseases.

InCNV: An Integrated Analysis Tool for Copy Number Variation on Whole Exome Sequencing.

The detection of copy number variations (CNVs) on whole-exome sequencing (WES) represents a cost-effective technique for the study of genetic variants. This approach, however, has encountered an obstacle with high false-positive rates due to biases from exome sequencing capture kits and GC contents. Although plenty of CNV detection tools have been developed, they do not perform well with all types of CNVs. In addition, most tools lack features of genetic annotation, CNV visualization, and flexible installation, requiring users to put much effort into CNV interpretation. Here, we present “inCNV,” a web-based application that can accept multiple CNV-tool results, then integrate and prioritize them with user-friendly interfaces. This application helps users analyze the importance of called CNVs by generating CNV annotations from Ensembl, Database of Genomic Variants (DGV), ClinVar, and Online Mendelian Inheritance in Man (OMIM). Moreover, users can select and export CNVs of interest including their flanking sequences for primer design and experimental verification. We demonstrated how inCNV could help users filter and narrow down the called CNVs to a potentially novel CNV, a common CNV within a group of samples of the same disease, or a de novo CNV of a sample within the same family. Besides, we have provided in CNV as a docker image for ease of installation (https://github.com/saowwapark/inCNV).

Molecular Characterization of Urothelial Carcinoma of the Bladder and Upper Urinary Tract

PURPOSE: A better understanding of the molecular basis of urothelial carcinoma (UC) is needed to refine the clinical decision-making process. METHODS AND MATERIALS: We performed next-generation sequencing to investigate the mutational and transcriptional profiles of commonly mutated genes in UC using Ampliseq v2. Copy number variations (CNVs) were detected with nCounter assay. Genetic alterations between upper tract UC (UTUC) and urinary bladder UC (UBUC) were compared. RESULTS: Tumor samples from 31 UTUC and 61 UBUC patients were included in analysis. The two groups showed similar clinicopathologic features including tumor grade and stage. Median survival was longer in UTUC than UBUC patients, though this was statistically nonsignificant (59 vs 41 months, P=.137). In total, we found 982 genetic alterations from 92 samples: single nucleotide variants were the most common type of somatic mutation (479/508, 94.3%). Frequently detected somatic mutations included TP53 (68.5%), KDR (41.3%), and PIK3CA (17.4%). Notably, RB1 mutations were the only mutations significantly different between the UBUC and UTUC groups (19.7% vs. 0%, P=.020). The most common types of CNVs included amplifications (56/62, 90.3%): 17.7% of patients identified amplifications in NOTCH1. We also identified five translocations in the entire study population, including one case with FGFR3-TACC3 (Chr4) fusion. CONCLUSION: Within a small study population, we identified similar genetic alterations in both UTUC and UBUC patients, indicating a basis for similar management strategies.

High resolution analysis of rare copy number variants in patients with autism spectrum disorder from Taiwan

Rare genomic copy number variations (CNVs) (frequency <1%) contribute a part to the genetic underpinnings of autism spectrum disorders (ASD). The study aimed to understand the scope of rare CNV in Taiwanese patients with ASD. We conducted a genome-wide CNV screening of 335 ASD patients (299 males, 36 females) from Taiwan using Affymetrix Genome-Wide Human SNP Array 6.0 and compared the incidence of rare CNV with that of 1093 control subjects (525 males, 568 females). We found a significantly increased global burden of rare CNVs in the ASD group compared to the controls as a whole or when the rare CNVs were classified by the size and types of CNV. Further analysis confirmed the presence of several rare CNVs at regions strongly associated with ASD as reported in the literature in our sample. Additionally, we detected several new private pathogenic CNVs in our samples and five patients carrying two pathogenic CNVs. Our data indicate that rare genomic CNVs contribute a part to the genetic landscape of our ASD patients. These CNVs are highly heterogeneous, and the clinical interpretation of the pathogenic CNVs of ASD is not straightforward in consideration of the incomplete penetrance, varied expressivity, and individual genetic background.

De novo and rare inherited copy-number variations in the hemiplegic form of cerebral palsy

PurposeHemiplegia is a subtype of cerebral palsy (CP) in which one side of the body is affected. Our earlier study of unselected children with CP demonstrated de novo and clinically relevant rare inherited genomic copy-number variations (CNVs) in 9.6% of participants. Here, we examined the prevalence and types of CNVs specifically in hemiplegic CP.MethodsWe genotyped 97 unrelated probands with hemiplegic CP and their parents. We compared their CNVs to those of 10,851 population controls, in order to identify rare CNVs (<0.1% frequency) that might be relevant to CP. We also sequenced exomes of “CNV-positive” trios.ResultsWe detected de novo CNVs and/or sex chromosome abnormalities in 7/97 (7.2%) of probands, impacting important developmental genes such as GRIK2, LAMA1, DMD, PTPRM, and DIP2C. In 18/97 individuals (18.6%), rare inherited CNVs were found, affecting loci associated with known genomic disorders (17p12, 22q11.21) or involving genes linked to neurodevelopmental disorders.ConclusionWe found an increased rate of de novo CNVs in the hemiplegic CP subtype (7.2%) compared to controls (1%). This result is similar to that for an unselected CP group. Combined with rare inherited CNVs, the genomic data impacts the understanding of the potential etiology of hemiplegic CP in 23/97 (23.7%) of participants.

Investigation of copy number variation in subjects with major depression based on whole-genome sequencing data

BackgroundDespite recent intensive research using genome-wide association studies, the underlying biological basis of major depressive disorder (MDD) still remains unknown. In contrast to genotyping platforms which identify specific variations, whole-genome sequencing (WGS) allows us to detect all private genetic variations within an individual. So far there have been no studies investigating copy number variations (CNVs) in subjects with MDD using WGS data. MethodsWe obtained complete WGS paired-end reads data of 15 MDD patients and 10 ethnically matched healthy controls. We performed alignments for the sequencing reads and used GASV package to call CNVs including deletion, inversion, translocation and divergence for those subjects. ResultsOur results show that, in the Mexican-American sample, deletion CNVs were significantly richer in MDD cases than healthy controls on each of 23 chromosomes. However, other types of CNVs failed to reach any significance. In the Australian sample, there was no statistically significant difference of CNVs between MDD cases and controls. Furthermore, we found that the Australian group had significantly more deletion CNVs than the Mexican-American group. LimitationsHigh quality WGS costs limited obtaining larger datasets. The GASV package does not currently support duplication or insertion CNVs. ConclusionsTo our knowledge this is the first time that CNVs detected by WGS data are used to study major depression. The conclusion that deletion CNVs are significantly richer in MDD cases than healthy controls is consistent with the previous finding about recurrent depressive disorder by genome-wide association analysis of CNVs on a large genotyping microarray data.

Unbalanced translocations arise from diverse mutational mechanisms including chromothripsis.

Unbalanced translocations are a relatively common type of copy number variation and a major contributor to neurodevelopmental disorders. We analyzed the breakpoints of 57 unique unbalanced translocations to investigate the mechanisms of how they form. Fifty-one are simple unbalanced translocations between two different chromosome ends, and six rearrangements have more than three breakpoints involving two to five chromosomes. Sequencing 37 breakpoint junctions revealed that simple translocations have between 0 and 4 base pairs (bp) of microhomology (n = 26), short inserted sequences (n = 8), or paralogous repeats (n = 3) at the junctions, indicating that translocations do not arise primarily from nonallelic homologous recombination but instead form most often via nonhomologous end joining or microhomology-mediated break-induced replication. Three simple translocations fuse genes that are predicted to produce in-frame transcripts of SIRPG-WWOX, SMOC2-PROX1, and PIEZO2-MTA1, which may lead to gain of function. Three complex translocations have inversions, insertions, and multiple breakpoint junctions between only two chromosomes. Whole-genome sequencing and fluorescence in situ hybridization analysis of two de novo translocations revealed at least 18 and 33 breakpoints involving five different chromosomes. Breakpoint sequencing of one maternally inherited translocation involving four chromosomes uncovered multiple breakpoints with inversions and insertions. All of these breakpoint junctions had 0–4 bp of microhomology consistent with chromothripsis, and both de novo events occurred on paternal alleles. Together with other studies, these data suggest that germline chromothripsis arises in the paternal genome and may be transmitted maternally. Breakpoint sequencing of our large collection of chromosome rearrangements provides a comprehensive analysis of the molecular mechanisms behind translocation formation.

Combinatorial approach to estimate copy number genotype using whole-exome sequencing data

Copy number variations (CNVs) are known risk factors in complex diseases. Array-based approaches have been widely used to detect CNVs, but limitations of array-based CNV detection methods, such as noisy signal and low resolution, have hindered detection of small CNVs.Recently, the development of next-generation sequencing techniques has increased rapidly owing to declines in cost. Particularly, whole-exome sequencing has proved useful for finding causal genes and variants in complex diseases. Because gene copy number may affect expression, CNV genotyping can be very valuable in disease association studies. However, almost all current CNV detection tools consider only two types of CNV genotypes.In this study, we propose a CNV genotype estimation approach using a combination of existing methods. Our approach was comprehensively compared with the customized Agilent array–comparative genomic hybridization. We found that our genotyping approach proved to be accurate, and reproducible, suggesting that it can complement existing CNV genotyping methods.

Copy number variations and human genetic disease.

Recent studies clearly demonstrate that copy number variations (CNVs) are widespread in our genome and play an important role in human genetic variation, accounting for both human population diversity and human genetic disease. This review will discuss the most current knowledge regarding our understanding of the biology of CNVs in relation to human genetic disease. CNVs associated with human genetic disease can be either recurrent, with a common size and breakpoint clustering, or nonrecurrent, with different sizes and variable breakpoints. Two types of recurrent CNVs have been distinguished, including the syndromic forms in which the phenotypic features are relatively consistent, and those in which the same recurrent CNV can be associated with a diverse set of diagnoses. Recently, the 'Two-hit model' was used to explain the phenotypic variability associated with the latter group of recurrent CNVs. Nonrecurrent CNVs, on the contrary, occur at a relatively lower frequency at the individual locus level but collectively they are as common as recurrent CNVs. Finally, the study of CNV burden in different diseases demonstrated a clear trend of an increasing CNV burden in diseases with more severe phenotypes. In spite of the advances in the study of the CNV landscape associated with human genetic disease, there still remain many unexplored questions especially regarding the role of CNVs in the pathogenesis of complex human genetic diseases.

HaplotypeCN: copy number haplotype inference with Hidden Markov Model and localized haplotype clustering.

Copy number variation (CNV) has been reported to be associated with disease and various cancers. Hence, identifying the accurate position and the type of CNV is currently a critical issue. There are many tools targeting on detecting CNV regions, constructing haplotype phases on CNV regions, or estimating the numerical copy numbers. However, none of them can do all of the three tasks at the same time. This paper presents a method based on Hidden Markov Model to detect parent specific copy number change on both chromosomes with signals from SNP arrays. A haplotype tree is constructed with dynamic branch merging to model the transition of the copy number status of the two alleles assessed at each SNP locus. The emission models are constructed for the genotypes formed with the two haplotypes. The proposed method can provide the segmentation points of the CNV regions as well as the haplotype phasing for the allelic status on each chromosome. The estimated copy numbers are provided as fractional numbers, which can accommodate the somatic mutation in cancer specimens that usually consist of heterogeneous cell populations. The algorithm is evaluated on simulated data and the previously published regions of CNV of the 270 HapMap individuals. The results were compared with five popular methods: PennCNV, genoCN, COKGEN, QuantiSNP and cnvHap. The application on oral cancer samples demonstrates how the proposed method can facilitate clinical association studies. The proposed algorithm exhibits comparable sensitivity of the CNV regions to the best algorithm in our genome-wide study and demonstrates the highest detection rate in SNP dense regions. In addition, we provide better haplotype phasing accuracy than similar approaches. The clinical association carried out with our fractional estimate of copy numbers in the cancer samples provides better detection power than that with integer copy number states.