• Journal of Genetic Medicine
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• 제7권2호
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• pp.119-124
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• 2010

약 7,000 여개의 단일유전자질환이 보고되어 있지만 보고된 질환의 절반도 아직 원인 유전자가 밝혀지지 못한 상황이다. 그리고 기존에 밝혀진 원인 유전자의 돌연변이형들은 대부분 단백질을 코딩하는 부위의 돌연변이에 의하여 발생하고 있어서 인간 유전체에서 단백질을 코딩하는 엑손 부위만을 선별적으로 분리하여 염기서열을 분석하는 엑솜 염기서열 분석 방법은 희귀한 유전질환의 신규 원인 유전자 발굴을 위한 매우 효과적인 유전 분석법이 될 것이다. 엑솜은 전체 유전체의 약 1.5% 정도를 차지하고 있어서 매우 경제적으로 분석이 가능하다. 그리고 엑솜 염기서열 분석 방법은 엑솜 부위를 선별하는 기술과 대용량 염기서열 분석기술로 수행된다. Freeman-Sheldon 증후군의 원인 유전자를 엑솜 염기서열 분석 방법으로 발굴한 이후로 단일유전자질환의 원인 유전자 발굴을 위한 표준 분석법으로 엑솜 염기서열 분석방법이 사용되고 있다. 향후에는 엑솜 염기서열 분석 방법이 다양한 복합질병의 유전분석에도 활용되어 개인 맞춤의학의 실현을 앞당기는데 크게 기여할 것으로 기대된다.

• Genomics & Informatics
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• 제20권3호
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• pp.28.1-28.7
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• 2022

We described a clinical, laboratory, and genetic presentation of a pathogenic variant of the CYP1B1 gene through a report of a case of primary congenital glaucoma and a trio analysis of this candidate variant in the family with the Sanger sequencing method and eventually completed our study with the secondary/incidental findings. This study reports a rare case of primary congenital glaucoma, an 8-year-old female child with a negative family history of glaucoma and uncontrolled intraocular pressure. This case's whole-exome sequencing data analysis presents a homozygous pathogenic single nucleotide variant in the CYP1B1 gene (NM_000104:exon3:c.G1103A:p.R368H). At the same time, this pathogenic variant was obtained as a heterozygous state in her unaffected father but not her mother. The diagnosis was made based on molecular findings of whole-exome sequencing data analysis. Therefore, the clinical reports and bioinformatics findings supported the relation between the candidate pathogenic variant and the disease. However, it should not be forgotten that primary congenital glaucoma is not peculiar to the CYP1B1 gene. Since the chance of developing autosomal recessive disorders with low allele frequency and unrelated parents is extraordinary in offspring. However, further data analysis of whole-exome sequencing and Sanger sequencing method were applied to obtain the type of mutation and how it was carried to the offspring.

• Genomics & Informatics
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• 제13권2호
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• pp.31-39
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• 2015

Sequencing depth, which is directly related to the cost and time required for the generation, processing, and maintenance of next-generation sequencing data, is an important factor in the practical utilization of such data in clinical fields. Unfortunately, identifying an exome sequencing depth adequate for clinical use is a challenge that has not been addressed extensively. Here, we investigate the effect of exome sequencing depth on the discovery of sequence variants for clinical use. Toward this, we sequenced ten germ-line blood samples from breast cancer patients on the Illumina platform GAII(x) at a high depth of ${\sim}200{\times}$. We observed that most function-related diverse variants in the human exonic regions could be detected at a sequencing depth of $120{\times}$. Furthermore, investigation using a diagnostic gene set showed that the number of clinical variants identified using exome sequencing reached a plateau at an average sequencing depth of about $120{\times}$. Moreover, the phenomena were consistent across the breast cancer samples.

• Journal of Interdisciplinary Genomics
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• 제2권1호
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• pp.10-12
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• 2020

Coffin-Lowry syndrome (CLS) is a genetic disorder characterized by intellectual disability, typical facial features, and skeletal abnormalities. But this syndrome shows highly variable clinical manifestations, and can't be diagnosed with conventional chromosome analysis or comparative genomic hybridization, leading to delayed diagnosis. Here we report an 18-year-old boy with CLS diagnosed by whole exome sequencing. Our patient initially presented with developmental delay, facial dysmorphism at the age of 1. At the age of 18, he developed orthopnea due to mitral regurgitation. At the 22 years of age, he was diagnosed as CLS diagnosed by whole exome sequencing. Our case implies that clinical suspicion is important for early diagnosis, and advanced diagnostic tools such as WES should be considered in suspected cases.

• Genomics & Informatics
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• 제10권4호
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• pp.214-219
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• 2012

The recent advent of next-generation sequencing technologies has dramatically changed the nature of biomedical research. Human genetics is no exception－it has never been easier to interrogate human patient genomes at the nucleotide level to identify disease-associated variants. To further facilitate the efficiency of this approach, whole exome sequencing (WES) was first developed in 2009. Over the past three years, multiple groups have demonstrated the power of WES through robust disease-associated variant discoveries across a diverse spectrum of human diseases. Here, we review the application of WES to different types of inherited human diseases and discuss analytical challenges and possible solutions, with the aim of providing a practical guide for the effective use of this technology.

• Journal of Genetic Medicine
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• 제20권2호
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• pp.31-38
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• 2023

Rare diseases, even though defined as fewer than 20,000 in South Korea, with over 8,000 rare Mendelian disorders having been identified, they collectively impact 6-8% of the global population. Many of the rare diseases pose significant challenges to patients, patients' families, and the healthcare system. The diagnostic journey for rare disease patients is often lengthy and arduous, hampered by the genetic diversity and phenotypic complexity of these conditions. With the advent of next-generation sequencing technology and clinical implementation of exome sequencing (ES) and genome sequencing (GS), the diagnostic rate for rare diseases is 25-50% depending on the disease category. It is also allowing more rapid new gene-disease association discovery and equipping us to practice precision medicine by offering tailored medical management plans, early intervention, family planning options. However, a substantial number of patients remain undiagnosed, and it could be due to several factors. Some may not have genetic disorders. Some may have disease-causing variants that are not detectable or interpretable by ES and GS. It's also possible that some patient might have a disease-causing variant in a gene that hasn't yet been linked to a disease. For patients who remain undiagnosed, reanalysis of existing data has shown promises in providing new molecular diagnoses achieved by new gene-disease associations, new variant discovery, and variant reclassification, leading to a 5-10% increase in the diagnostic rate. More advanced approach such as long-read sequencing, transcriptome sequencing and integration of multi-omics data may provide potential values in uncovering elusive genetic causes.

• Journal of Genetic Medicine
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• 제15권2호
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• pp.87-91
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• 2018

X-linked dominant mutations in lysosome-associated membrane protein 2 (LAMP2) gene have been shown to be the cause of Danon disease, which is a rare disease associated with clinical triad of cardiomyopathy, skeletal myopathy, and mental retardation. Cardiac involvement is a common manifestation and is the leading cause of death in Danon disease. We report a case of a 24-month-old boy with hemizygous LAMP2 mutation who presented with failure to thrive and early-onset hypertrophic cardiomyopathy. We applied targeted exome sequencing and found a novel hemizygous c.692del variant in exon 5 of the LAMP2 gene, resulting a frameshift mutation p.Thr231Ilefs*11. Our study indicates that target next-generation sequencing can be used as a fast and highly sensitive screening method for inherited cardiomyopathy.

• Genomics & Informatics
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• 제18권1호
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• pp.3.1-3.8
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• 2020

Patient-derived xenograft (PDX) mouse models are frequently used to test the drug efficacy in diverse types of cancer. They are known to recapitulate the patient characteristics faithfully, but a systematic survey with a large number of cases is yet missing in lung cancer. Here we report the comparison of genomic characters between mouse and patient tumor tissues in lung cancer based on exome sequencing data. We established PDX mouse models for 132 lung cancer patients and performed whole exome sequencing for trio samples of tumor-normal-xenograft tissues. Then we computed the somatic mutations and copy number variations, which were used to compare the PDX and patient tumor tissues. Genomic and histological conclusions for validity of PDX models agreed in most cases, but we observed eight (~7%) discordant cases. We further examined the changes in mutations and copy number alterations in PDX model production and passage processes, which highlighted the clonal evolution in PDX mouse models. Our study shows that the genomic characterization plays complementary roles to the histological examination in cancer studies utilizing PDX mouse models.

• Journal of Korean Neurosurgical Society
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• 제63권5호
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• pp.559-565
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• 2020

Objective : Conflicting results regarding SOX17 genes and the risk of intracranial aneurysms (IA) exist in the Korean population, although significant positive correlations were noted in genome-wide association studies in European and Japanese populations. Therefore, we aimed to investigate an association between SOX17 gene variants and IA using exome sequencing data. Methods : This study included 26 age-gender matched IA patients and 26 control subjects. The SOX17 gene variants identified from whole-exome sequencing data were examined. Genetic associations to estimate odds ratio (OR) and 95% confidence interval (CI) were performed using the software EPACTS. Results : The mean age of the IA and control groups were 51.0±9.3 years and 49.4±14.3 years, respectively (p=0.623). Seven variants of SOX17, including six single nucleotide polymorphisms and one insertion and deletion, were observed. Among these variants, rs12544958 (A>G) showed the most association with IA, but the association was not statistically significant (OR, 1.97; 95% CI, 0.81-4.74; p=0.125). Minor allele frequencies of the IA patients and controls were 0.788 and 0.653, respectively. None of the remaining variants were significantly associated with IA formation. Conclusion : No significant association between SOX17 gene variants and IA were noted in the Korean population. A large-scale exome sequencing study is necessary to investigate any Korean-specific genetic susceptibility to IA.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• 제24권1호
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• pp.1-6
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• 2021

Next-generation sequencing (NGS) technologies have changed the process of genetic diagnosis from a gene-by-gene approach to syndrome-based diagnostic gene panel sequencing (DPS), diagnostic exome sequencing (DES), and diagnostic genome sequencing (DGS). A priori information on the causative genes that might underlie a genetic condition is a prerequisite for genetic diagnosis before conducting clinical NGS tests. Theoretically, DPS, DES, and DGS do not require any information on specific candidate genes. Therefore, clinical NGS tests sometimes detect disease-related pathogenic variants in genes underlying different conditions from the initial diagnosis. These clinical NGS tests are expensive, but they can be a cost-effective approach for the rapid diagnosis of rare disorders with genetic heterogeneity, such as the glycogen storage disease, familial intrahepatic cholestasis, lysosomal storage disease, and primary immunodeficiency. In addition, DES or DGS may find novel genes that that were previously not linked to human diseases.