Purpose: Considering the high disease burden and unique features of Asian patients with breast cancer (BC), it is essential to have a comprehensive view of genetic characteristics in this population. An institutional targeted sequencing platform was developed through the Korea Research-Driven Hospitals project and was incorporated into clinical practice. This study explores the use of targeted next-generation sequencing (NGS) and its outcomes in patients with advanced/metastatic BC in the real world. Materials and Methods: We reviewed the results of NGS tests administered to BC patients using a customized sequencing platform—FiRST Cancer Panel (FCP)—over 7 years. We systematically described clinical translation of FCP for precise diagnostics, personalized therapeutic strategies, and unraveling disease pathogenesis. Results: NGS tests were conducted on 548 samples from 522 patients with BC. Ninety-seven point six percentage of tested samples harbored at least one pathogenic alteration. The common alterations included mutations in TP53 (56.2%), PIK3CA (31.2%), GATA3 (13.8%), BRCA2 (10.2%), and amplifications of CCND1 (10.8%), FGF19 (10.0%), and ERBB2 (9.5%). NGS analysis of ERBB2 amplification correlated well with human epidermal growth factor receptor 2 immunohistochemistry and in situ hybridization. RNA panel analyses found potentially actionable and prognostic fusion genes. FCP effectively screened for potentially germline pathogenic/likely pathogenic mutation. Ten point three percent of BC patients received matched therapy guided by NGS, resulting in a significant overall survival advantage (p=0.022), especially for metastatic BCs. Conclusion Clinical NGS provided multifaceted benefits, deepening our understanding of the disease, improving diagnostic precision, and paving the way for targeted therapies. The concrete advantages of FCP highlight the importance of multi-gene testing for BC, especially for metastatic conditions.

Purpose: Considering the high disease burden and unique features of Asian patients with breast cancer (BC), it is essential to have a comprehensive view of genetic characteristics in this population. An institutional targeted sequencing platform was developed through the Korea Research-Driven Hospitals project and was incorporated into clinical practice. This study explores the use of targeted next-generation sequencing (NGS) and its outcomes in patients with advanced/metastatic BC in the real world. Materials and Methods: We reviewed the results of NGS tests administered to BC patients using a customized sequencing platform—FiRST Cancer Panel (FCP)—over 7 years. We systematically described clinical translation of FCP for precise diagnostics, personalized therapeutic strategies, and unraveling disease pathogenesis. Results: NGS tests were conducted on 548 samples from 522 patients with BC. Ninety-seven point six percentage of tested samples harbored at least one pathogenic alteration. The common alterations included mutations in TP53 (56.2%), PIK3CA (31.2%), GATA3 (13.8%), BRCA2 (10.2%), and amplifications of CCND1 (10.8%), FGF19 (10.0%), and ERBB2 (9.5%). NGS analysis of ERBB2 amplification correlated well with human epidermal growth factor receptor 2 immunohistochemistry and in situ hybridization. RNA panel analyses found potentially actionable and prognostic fusion genes. FCP effectively screened for potentially germline pathogenic/likely pathogenic mutation. Ten point three percent of BC patients received matched therapy guided by NGS, resulting in a significant overall survival advantage (p=0.022), especially for metastatic BCs. Conclusion Clinical NGS provided multifaceted benefits, deepening our understanding of the disease, improving diagnostic precision, and paving the way for targeted therapies. The concrete advantages of FCP highlight the importance of multi-gene testing for BC, especially for metastatic conditions.

Purpose: Considering the high disease burden and unique features of Asian patients with breast cancer (BC), it is essential to have a comprehensive view of genetic characteristics in this population. An institutional targeted sequencing platform was developed through the Korea Research-Driven Hospitals project and was incorporated into clinical practice. This study explores the use of targeted next-generation sequencing (NGS) and its outcomes in patients with advanced/metastatic BC in the real world. Materials and Methods: We reviewed the results of NGS tests administered to BC patients using a customized sequencing platform—FiRST Cancer Panel (FCP)—over 7 years. We systematically described clinical translation of FCP for precise diagnostics, personalized therapeutic strategies, and unraveling disease pathogenesis. Results: NGS tests were conducted on 548 samples from 522 patients with BC. Ninety-seven point six percentage of tested samples harbored at least one pathogenic alteration. The common alterations included mutations in TP53 (56.2%), PIK3CA (31.2%), GATA3 (13.8%), BRCA2 (10.2%), and amplifications of CCND1 (10.8%), FGF19 (10.0%), and ERBB2 (9.5%). NGS analysis of ERBB2 amplification correlated well with human epidermal growth factor receptor 2 immunohistochemistry and in situ hybridization. RNA panel analyses found potentially actionable and prognostic fusion genes. FCP effectively screened for potentially germline pathogenic/likely pathogenic mutation. Ten point three percent of BC patients received matched therapy guided by NGS, resulting in a significant overall survival advantage (p=0.022), especially for metastatic BCs. Conclusion Clinical NGS provided multifaceted benefits, deepening our understanding of the disease, improving diagnostic precision, and paving the way for targeted therapies. The concrete advantages of FCP highlight the importance of multi-gene testing for BC, especially for metastatic conditions.

Background: Hypertrophic cardiomyopathy (HCM) needs careful differentiation from other cardiomyopathies. Current guidelines recommend genetic testing, but genetic data on differential diagnoses and their relation with clinical outcomes in HCM are still lacking.This study aimed to investigate the prevalence of genetic variants and the proportion of other cardiomyopathies in patients with suspected HCM in Korea and compare the outcomes of HCM according to the presence of sarcomere gene mutation. Methods: We enrolled 1,554 patients with suspected HCM having left ventricular hypertrophy on transthoracic echocardiography between April 2012 and February 2023. Patients who declined genetic testing or who had pure apical HCM without a familial history were excluded. Genetic testing was performed using a next-generation sequencing panel or wholeexome sequencing for cardiomyopathies. We performed cardiovascular magnetic resonance if the diagnosis was inconclusive. Genotype-positive HCM was defined as sarcomere gene mutations of pathogenic or likely pathogenic variants. Adverse clinical outcomes were defined as a composite of all-cause death, resuscitated cardiac arrest, heart failure-related admission, appropriate implantable cardioverter defibrillator shocks, and stroke. Results: Of 492 patients (mean age 49.6 ± 14.7 years, 29.4% women) who underwent genetic testing, 214 (43.5%) had disease-causing gene mutations. After combining gene tests, multi-imaging modality, and clinical information, 447 (90.9%) had HCM, and 27 (5.5%) had Fabry disease. Among the HCM patients, 182 (40.7%) were genotype-positive, and 265 (59.3%) were genotype-negative. Kaplan–Meier curve analysis showed that genotype-positive HCM patients experienced more composite outcomes (log-rank, P < 0.001). In multivariable Cox analysis, non-sustained ventricular tachycardia (NSVT) (hazard ratio [HR], 1.91; 95% confidence interval [CI], 1.17–3.12; P = 0.010), left ventricular ejection fraction (LVEF) < 50% (HR, 5.50; 95% CI, 2.68–11.27; P < 0.001), LA reservoir strain (HR, 0.96; 95% CI, 0.93–0.99;P = 0.037), and positive sarcomere gene mutation (HR, 1.70; 95% CI, 1.04–2.78; P = 0.034) were significantly association with composite outcomes. Sarcomere gene mutation had incremental value for predicting adverse outcomes added on NSVT and LVEF < 50%. Conclusion Genetic testing is helpful in diagnosing HCM, and sarcomere gene mutations in HCM are significantly associated with clinical outcomes.

Background: Hypertrophic cardiomyopathy (HCM) needs careful differentiation from other cardiomyopathies. Current guidelines recommend genetic testing, but genetic data on differential diagnoses and their relation with clinical outcomes in HCM are still lacking.This study aimed to investigate the prevalence of genetic variants and the proportion of other cardiomyopathies in patients with suspected HCM in Korea and compare the outcomes of HCM according to the presence of sarcomere gene mutation. Methods: We enrolled 1,554 patients with suspected HCM having left ventricular hypertrophy on transthoracic echocardiography between April 2012 and February 2023. Patients who declined genetic testing or who had pure apical HCM without a familial history were excluded. Genetic testing was performed using a next-generation sequencing panel or wholeexome sequencing for cardiomyopathies. We performed cardiovascular magnetic resonance if the diagnosis was inconclusive. Genotype-positive HCM was defined as sarcomere gene mutations of pathogenic or likely pathogenic variants. Adverse clinical outcomes were defined as a composite of all-cause death, resuscitated cardiac arrest, heart failure-related admission, appropriate implantable cardioverter defibrillator shocks, and stroke. Results: Of 492 patients (mean age 49.6 ± 14.7 years, 29.4% women) who underwent genetic testing, 214 (43.5%) had disease-causing gene mutations. After combining gene tests, multi-imaging modality, and clinical information, 447 (90.9%) had HCM, and 27 (5.5%) had Fabry disease. Among the HCM patients, 182 (40.7%) were genotype-positive, and 265 (59.3%) were genotype-negative. Kaplan–Meier curve analysis showed that genotype-positive HCM patients experienced more composite outcomes (log-rank, P < 0.001). In multivariable Cox analysis, non-sustained ventricular tachycardia (NSVT) (hazard ratio [HR], 1.91; 95% confidence interval [CI], 1.17–3.12; P = 0.010), left ventricular ejection fraction (LVEF) < 50% (HR, 5.50; 95% CI, 2.68–11.27; P < 0.001), LA reservoir strain (HR, 0.96; 95% CI, 0.93–0.99;P = 0.037), and positive sarcomere gene mutation (HR, 1.70; 95% CI, 1.04–2.78; P = 0.034) were significantly association with composite outcomes. Sarcomere gene mutation had incremental value for predicting adverse outcomes added on NSVT and LVEF < 50%. Conclusion Genetic testing is helpful in diagnosing HCM, and sarcomere gene mutations in HCM are significantly associated with clinical outcomes.

Background: Hypertrophic cardiomyopathy (HCM) needs careful differentiation from other cardiomyopathies. Current guidelines recommend genetic testing, but genetic data on differential diagnoses and their relation with clinical outcomes in HCM are still lacking.This study aimed to investigate the prevalence of genetic variants and the proportion of other cardiomyopathies in patients with suspected HCM in Korea and compare the outcomes of HCM according to the presence of sarcomere gene mutation. Methods: We enrolled 1,554 patients with suspected HCM having left ventricular hypertrophy on transthoracic echocardiography between April 2012 and February 2023. Patients who declined genetic testing or who had pure apical HCM without a familial history were excluded. Genetic testing was performed using a next-generation sequencing panel or wholeexome sequencing for cardiomyopathies. We performed cardiovascular magnetic resonance if the diagnosis was inconclusive. Genotype-positive HCM was defined as sarcomere gene mutations of pathogenic or likely pathogenic variants. Adverse clinical outcomes were defined as a composite of all-cause death, resuscitated cardiac arrest, heart failure-related admission, appropriate implantable cardioverter defibrillator shocks, and stroke. Results: Of 492 patients (mean age 49.6 ± 14.7 years, 29.4% women) who underwent genetic testing, 214 (43.5%) had disease-causing gene mutations. After combining gene tests, multi-imaging modality, and clinical information, 447 (90.9%) had HCM, and 27 (5.5%) had Fabry disease. Among the HCM patients, 182 (40.7%) were genotype-positive, and 265 (59.3%) were genotype-negative. Kaplan–Meier curve analysis showed that genotype-positive HCM patients experienced more composite outcomes (log-rank, P < 0.001). In multivariable Cox analysis, non-sustained ventricular tachycardia (NSVT) (hazard ratio [HR], 1.91; 95% confidence interval [CI], 1.17–3.12; P = 0.010), left ventricular ejection fraction (LVEF) < 50% (HR, 5.50; 95% CI, 2.68–11.27; P < 0.001), LA reservoir strain (HR, 0.96; 95% CI, 0.93–0.99;P = 0.037), and positive sarcomere gene mutation (HR, 1.70; 95% CI, 1.04–2.78; P = 0.034) were significantly association with composite outcomes. Sarcomere gene mutation had incremental value for predicting adverse outcomes added on NSVT and LVEF < 50%. Conclusion Genetic testing is helpful in diagnosing HCM, and sarcomere gene mutations in HCM are significantly associated with clinical outcomes.

Background: Hypertrophic cardiomyopathy (HCM) needs careful differentiation from other cardiomyopathies. Current guidelines recommend genetic testing, but genetic data on differential diagnoses and their relation with clinical outcomes in HCM are still lacking.This study aimed to investigate the prevalence of genetic variants and the proportion of other cardiomyopathies in patients with suspected HCM in Korea and compare the outcomes of HCM according to the presence of sarcomere gene mutation. Methods: We enrolled 1,554 patients with suspected HCM having left ventricular hypertrophy on transthoracic echocardiography between April 2012 and February 2023. Patients who declined genetic testing or who had pure apical HCM without a familial history were excluded. Genetic testing was performed using a next-generation sequencing panel or wholeexome sequencing for cardiomyopathies. We performed cardiovascular magnetic resonance if the diagnosis was inconclusive. Genotype-positive HCM was defined as sarcomere gene mutations of pathogenic or likely pathogenic variants. Adverse clinical outcomes were defined as a composite of all-cause death, resuscitated cardiac arrest, heart failure-related admission, appropriate implantable cardioverter defibrillator shocks, and stroke. Results: Of 492 patients (mean age 49.6 ± 14.7 years, 29.4% women) who underwent genetic testing, 214 (43.5%) had disease-causing gene mutations. After combining gene tests, multi-imaging modality, and clinical information, 447 (90.9%) had HCM, and 27 (5.5%) had Fabry disease. Among the HCM patients, 182 (40.7%) were genotype-positive, and 265 (59.3%) were genotype-negative. Kaplan–Meier curve analysis showed that genotype-positive HCM patients experienced more composite outcomes (log-rank, P < 0.001). In multivariable Cox analysis, non-sustained ventricular tachycardia (NSVT) (hazard ratio [HR], 1.91; 95% confidence interval [CI], 1.17–3.12; P = 0.010), left ventricular ejection fraction (LVEF) < 50% (HR, 5.50; 95% CI, 2.68–11.27; P < 0.001), LA reservoir strain (HR, 0.96; 95% CI, 0.93–0.99;P = 0.037), and positive sarcomere gene mutation (HR, 1.70; 95% CI, 1.04–2.78; P = 0.034) were significantly association with composite outcomes. Sarcomere gene mutation had incremental value for predicting adverse outcomes added on NSVT and LVEF < 50%. Conclusion Genetic testing is helpful in diagnosing HCM, and sarcomere gene mutations in HCM are significantly associated with clinical outcomes.

Allan-Herndon-Dudley syndrome (AHDS) is a rare X-linked neurodevelopmental disorder with abnormal thyroid function caused by mutation in the solute carrier family 16 member 2 (SLC16A2) gene. Clinical manifestations of AHDS are global or axial hypotonia, a variety of movement disorders, severe intellectual disability, quadriplegia or spastic diplegia, growth failure, and seizures. A 10-year-old boy visited our hospital with the chief complaint of newly onset generalized tonic seizures with vocalization of weekly to daily frequency. He showed early infantile hypotonia, severe intellectual disability, and frequent respiratory infections. He could not walk independently and was non-verbal. Electroencephalogram revealed generalized slow spike and waves with multifocal spikes and slow background rhythms. His tonic seizures were controlled with more than two anti-seizure medications (ASMs). At 11 years of age, he was evaluated for thyroid function as part of regular screening for ASM maintenance and was found to have abnormal thyroid function. We performed whole exome sequencing for severe global developmental delay, drug-resistant epilepsy, and abnormal thyroid function. The hemizygous c.940C>T (p.Arg314Ter) variant in the SLC16A2 gene (NM_006517.5) was identified and confirmed based on Sanger sequencing. Herein, we describe a case of an AHDS patient with late-onset drug-resistant epilepsy combined with congenital hypotonia, global developmental delay, and abnormal thyroid function results. To the best of our knowledge, this is the oldest adolescent among AHDS cases reported in Korea. In this report, clinical characteristics of a mid-adolescence patient with AHDS were presented.

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 nextgeneration 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.