Analysis of low-level somatic mosaicism reveals stage and tissue-specific mutational features in human development.

Most somatic mutations that arise during normal development are present at low levels in single or multiple tissues depending on the developmental stage and affected organs. However, the effect of human developmental stages or mutations of different organs on the features of somatic mutations is still unclear. Here, we performed a systemic and comprehensive analysis of low-level somatic mutations using deep whole-exome sequencing (average read depth ~500×) of 498 multiple organ tissues with matched controls from 190 individuals. Our results showed that early clone-forming mutations shared between multiple organs were lower in number but showed higher allele frequencies than late clone-forming mutations [0.54 vs. 5.83 variants per individual; 6.17% vs. 1.5% variant allele frequency (VAF)] along with less nonsynonymous mutations and lower functional impacts. Additionally, early and late clone-forming mutations had unique mutational signatures that were distinct from mutations that originated from tumors. Compared with early clone-forming mutations that showed a clock-like signature across all organs or tissues studied, late clone-forming mutations showed organ, tissue, and cell-type specificity in the mutation counts, VAFs, and mutational signatures. In particular, analysis of brain somatic mutations showed a bimodal occurrence and temporal-lobe-specific signature. These findings provide new insights into the features of somatic mosaicism that are dependent on developmental stage and brain regions.

Clinical and molecular characteristics of Korean patients with Kabuki syndrome.

INTRODUCTION: Kabuki syndrome (KS) is a rare disorder characterized by typical facial features, skeletal anomalies, fetal fingertip pad persistence, postnatal growth retardation, and intellectual disabilities. Heterozygous variants of the KMT2D and KDM6A genes are major genetic causes of KS. This study aimed to report the clinical and genetic characteristics of KS. METHODS: This study included 28 Korean patients (14 boys and 14 girls) with KS through molecular genetic testing, including direct Sanger sequencing, whole-exome sequencing, or whole-genome sequencing. RESULTS: The median age at clinical diagnosis was 18.5 months (IQR 7-58 months), and the median follow-up duration was 80.5 months (IQR 48-112 months). Molecular genetic testing identified different pathogenic variants of the KMT2D (n = 23) and KDM6A (n = 3) genes, including 15 novel variants. Patients showed typical facial features (100%), such as long palpebral fissure and eversion of the lower eyelid; intellectual disability/developmental delay (96%); short stature (79%); and congenital cardiac anomalies (75%). Although 71% experienced failure to thrive in infancy, 54% of patients showed a tendency toward overweight/obesity in early childhood. Patients with KDM6A variants demonstrated severe genotype-phenotype correlation. CONCLUSION: This study enhances the understanding of the clinical and genetic characteristics of KS.

Ultra-Low Level Somatic Mutations and Structural Variations in Focal Cortical Dysplasia Type II.

OBJECTIVE: Brain somatic mutations in mTOR pathway genes are a major genetic etiology of focal cortical dysplasia type II (FCDII). Despite a greater ability to detect low-level somatic mutations in the brain by deep sequencing and analytics, about 40% of cases remain genetically unexplained. METHODS: We included 2 independent cohorts consisting of 21 patients with mutation-negative FCDII without apparent mutations on conventional deep sequencing of bulk brain. To find ultra-low level somatic variants or structural variants, we isolated cells exhibiting phosphorylation of the S6 ribosomal protein (p-S6) in frozen brain tissues using fluorescence-activated cell sorting (FACS). We then performed deep whole-genome sequencing (WGS; >90×) in p-S6+ cells in a cohort of 11 patients with mutation-negative. Then, we simplified the method to whole-genome amplification and target gene sequencing of p-S6+ cells in independent cohort of 10 patients with mutation-negative followed by low-read depth WGS (10×). RESULTS: We found that 28.6% (6 of 21) of mutation-negative FCDII carries ultra-low level somatic mutations (less than 0.2% of variant allele frequency [VAF]) in mTOR pathway genes. Our method showed ~34 times increase of the average mutational burden in FACS mediated enrichment of p-S6+ cells (average VAF = 5.84%) than in bulky brain tissues (average VAF = 0.17%). We found that 19% (4 of 21) carried germline structural variations in GATOR1 complex undetectable in whole exome or targeted gene sequencing. CONCLUSIONS: Our method facilitates the detection of ultra-low level somatic mutations, in specifically p-S6+ cells, and germline structural variations and increases the genetic diagnostic rate up to ~80% for the entire FCDII cohort. ANN NEUROL 2023;93:1082-1093.

Etiologic distribution and clinical characteristics of pediatric diabetes in 276 children and adolescents with diabetes at a single academic center.

BACKGROUND: The prevalence of monogenic diabetes is estimated to be 1.1-6.3% of patients with diabetes mellitus (DM) in Europe. The overlapping clinical features of various forms of diabetes make differential diagnosis challenging. Therefore, this study investigated the etiologic distribution and clinical characteristics of pediatric diabetes, including monogenic diabetes, who presented at a single tertiary center over the last 20 years. METHODS: This study included 276 consecutive patients with DM diagnosed before 18 years of age from January 2000 to December 2019 in Korea. Clinical features, biochemical findings, ß-cell autoantibodies, and molecular characteristics were reviewed retrospectively. RESULTS: Of the 276 patients, 206 patients (74.6%), 49 patients (17.8%), and 21 patients (7.6%) were diagnosed with type 1 DM, type 2 DM, and clinically suspected monogenic diabetes, respectively. Among 21 patients suspected to have monogenic diabetes, 8 patients had clinical maturity-onset diabetes of the young (MODY), and the remaining 13 patients had other types of monogenic diabetes. Among them, genetic etiologies were identified in 14 patients (5.1%) from 13 families, which included MODY 5, transient neonatal DM, developmental delay, epilepsy, and neonatal diabetes (DEND) syndrome, Wolfram syndrome, Donohue syndrome, immune dysregulation, polyendocrinopathy, enteropathy, X-linked (IPEX) syndrome, Fanconi-Bickel syndrome, Wolcott-Rallison syndrome, cystic fibrosis-related diabetes, and maternally inherited diabetes and deafness. CONCLUSIONS: Genetically confirmed monogenic diabetes accounted for 5.1% of patients evaluated at a single tertiary center over 20-year period. Based on the findings for our sample, the frequency of mutations in the major genes of MODY appears to be low among pediatric patients in Korea. It is critical to identify the genetic cause of DM to provide appropriate therapeutic options and genetic counseling.

Investigation of Clinical and Pathological Relationships between Adult- and Pediatric-type NASH in Korean Children.

BACKGROUND: Histologically, nonalcoholic steatohepatitis (NASH) is categorized into adult-type (type 1) and pediatric-type (type 2). The origination of the histological difference between the two types and how they differ clinically remain uncertain. We aimed to understand the incidence and clinical characteristics of the two types of NASH in Korean children, and to investigate the association between their pathological type and clinical characteristics, using anthropometric and laboratory data. METHODS: In 38 children with confirmed NASH, we investigated hepatic pathological findings, and correlating factors between pathological type and laboratory and anthropometric data (weight percentile, body mass index (BMI) z-score, and blood pressure percentile). Adult-type NASH was noted in 21 patients and pediatric-type in 17 patients. RESULTS: Age, sex, BMI, transaminase levels, and insulin resistance were not significantly different between the two groups. Triglyceride (TG) levels were higher in adult-type NASH (P = 0.033). Hematocrit and albumin levels were lower in adult-type NASH (P = 0.016 and 0.013, respectively). Hepatic fibrosis was more common in pediatric-type. The fibrosis scores in patients with adult-type were mostly 0 and 1, whereas the score was 3 in patients with pediatric-type (P = 0.024, 0.004, and < 0.010, respectively). Anthropometric data, liver function, and insulin resistance scores did not differ between the two pathological NASH types. TG, hematocrit, and albumin may be potential factors to predict pathological types. Fibrosis was observed more frequently in pediatric-type NASH. CONCLUSION: Monitoring children with pediatric-type NASH for progression to fibrosis or cirrhosis is recommended.

Determination of Autosomal Dominant or Recessive Methionine Adenosyltransferase I/III Deficiencies Based on Clinical and Molecular Studies.

Methionine adenosyltransferase (MAT) I/III deficiency can be inherited as autosomal dominant (AD) or as recessive (AR) traits in which mono- or biallelic MAT1A mutations have been identified, respectively. Although most patients have benign clinical outcomes, some with the AR form have neurological deficits. Here we describe 16 Korean patients with MAT I/III deficiency from 15 unrelated families identified by newborn screening. Ten probands had the AD MAT I/III deficiency, while six had AR MAT I/III deficiency. Plasma methionine (145.7 µmol/L versus 733.2 µmol/L, P < 0.05) and homocysteine levels (12.3 µmol/L versus 18.6 µmol/L, P < 0.05) were lower in the AD type than in AR type. In addition to the only reported AD MAT1A mutation, p.Arg264His, we identified two novel AD mutations, p.Arg249Gln and p.Gly280Arg. In the AR type, four previously reported and two novel mutations, p.Arg163Trp and p.Tyr335*, were identified. No exonic deletions were found by quantitative genomic polymerase chain reaction (PCR). Three-dimensional structural prediction programs indicated that the AD-type mutations were located on the dimer interface or in the substrate binding site, hindering MAT I/III dimerization or substrate binding, respectively, whereas the AR mutations were distant from the interface or substrate binding site. These results indicate that the AD or AR MAT I/III deficiency is correlated with clinical findings, substrate levels and structural features of the mutant proteins, which is important for the neurological management and genetic counseling of the patients.

Long-term enzyme replacement therapy for Fabry disease: efficacy and unmet needs in cardiac and renal outcomes.

Fabry disease is a progressive lysosomal storage disease caused by alpha-galactosidase A deficiency. This condition is characterized by progressive accumulation of glycosphingolipids with functional impairment in various organs, including the kidney, heart and cerebrovascular system. Enzyme replacement therapy (ERT) is essential because it attenuates the disease progression. The present study investigated the long-term efficacy of ERT in 19 Korean Fabry patients (11 adult males, 4 symptomatic female carriers and 4 pediatric males) who had received ERT for 8.1±2.2 years (range, 5.3-10.5 years). In the 11 adult males, the mean reduction in the estimated glomerular filtration rate (eGFR) was -3.8±4.5 ml-1 min 1.73 m-2. The rate of eGFR decline was significantly lower in patients with lower proteinuria (<1 g per day) before ERT. The left ventricular mass index decreased or was stable throughout the ERT in male patients with or without left ventricular hypertrophy before ERT initiation. In female carriers and pediatric male patients, renal and cardiac functions remained stable with ERT. Arrhythmias were observed in 10 adult males and 1 female patient before ERT and persisted during ERT. One pediatric patient newly developed arrhythmia despite ERT. In conclusion, long-term ERT has beneficial effects on the renal and cardiac outcomes of Fabry patients but has limited effect in patients with irreversible organ damage. Identification of patients in the early disease stage and rapid ERT initiation might be the best strategy to improve the natural course of the disease.

Short-term efficacy of N-carbamylglutamate in a patient with N-acetylglutamate synthase deficiency.

N-acetylglutamate synthase (NAGS) deficiency is a rare inborn error regarding the urea cycle, however, its diagnosis is important as it can be effectively treated by N-carbamylglutamate. We evaluated a patient with NAGS deficiency who harbored two novel NAGS mutations and who showed excellent responsiveness during 1 year of N-carbamylglutamate treatment.

Clinical outcomes and the mutation spectrum of the OTC gene in patients with ornithine transcarbamylase deficiency.

Ornithine transcarbamylase (OTC) deficiency is an X-linked inborn error of the urea cycle that leads to the accumulation of ammonia, resulting in neurological deficits. This study was performed to describe the clinical outcomes, biochemical features and molecular spectra of patients with OTC deficiency. A total of 49 patients from 47 unrelated Korean pedigrees were included who were diagnosed with OTC deficiency based on biochemical findings and molecular analyses. Patient clinical features,biochemical findings and molecular data were analyzed retrospectively. Males with neonatal-onset phenotype presented with seizure or altered mentality (n=20). Biochemical findings showed high blood ammonia (1132.5±851.6 µmol l (− 1)) and urineorotic acid (1840.7±1731.3 mmol mol(− 1) Cr) levels. There were also five males with late-onset disease who presented with vomiting, irritability and seizure at age 8.2±9.4 years old (range, 0.6­20 years). Symptomatic females presented with vomiting,seizure, and altered mentality at age 3.5±3.5 years (range, 0.2­12.8 years; n=24). More males with the late-onset form and symptomatic females displayed mild hyperammonemia and orotic aciduria compared with those showing a neonatal phenotype (P<0.05). Molecular analysis identified 37 different mutations (22 missense, 5 large deletions, 4 small deletions, 1 insertion,3 nonsense and 2 splice sites) from all 49 patients; the mutations were dispersed throughout all coding exons. In Korean patients with OTC deficiency, mutations in OTC are genetically heterogeneous. Male patients with the neonatal-onset phenotype showed poor outcomes because of severe hyperammonemia. Early diagnosis and interventions for hyperammonemia can provide more favorable prognosis.

Diverse genetic aetiologies and clinical outcomes of paediatric hypoparathyroidism.

CONTEXT: Hypoparathyroidism is characterized by hypocalcaemia, hyperphosphataemia, and low or inappropriately normal parathyroid hormone (PTH) levels. Idiopathic or genetic drivers are the predominant causes of hypoparathyroidism in paediatric-age patients. OBJECTIVE: This study investigated the aetiology and clinical course of primary hypoparathyroidism in infancy and childhood. SUBJECTS AND MEASUREMENTS: This study included 37 patients (23 males, 14 females) with primary hypoparathyroidism diagnosed prior to 18 years of age. We analysed aetiologies, initial presentation, age at diagnosis, endocrine and radiological findings, and outcomes. RESULTS: The median age at presentation was 1·7 months (range 1 day-17 years), and the mean follow-up duration was 7·0 ± 5·3 years (range 0·5-16·8 years). Our cohort included 22 cases (59·5%) of 22q11·2 microdeletion syndrome. Other aetiologies included hypoparathyroidism-deafness-renal dysplasia syndrome (5/37, 13·5%) and one patient each with autoimmune polyglandular syndrome type 1, Kearns-Sayre syndrome and Kenny-Caffey syndrome. The remaining 7 (18·9%) patients were classified as idiopathic hypoparathyroidism cases. Among the 15 patients who underwent brain imaging, 5 (33·3%) had basal ganglia calcification. Among the 26 patients examined by renal imaging, 5 (19·2%) had either nephrocalcinosis or a renal stone. After 11 months of calcium or calcitriol supplementation, 16 patients (43·2%) discontinued medication. The final PTH levels were significantly higher in patients with transient hypoparathyroidism than those with permanent hypoparathyroidism. CONCLUSIONS: Identification of the genetic aetiologies of hypoparathyroidism makes it possible to predict patient outcomes and provide appropriate genetic counselling. Long-term treatment with calcium and calcitriol necessitates monitoring for renal complications.

Novel mutations and clinical outcomes of copper-histidine therapy in Menkes disease patients.

Menkes disease is a very rare X-linked copper metabolism disorder that results from an ATP7A gene mutation. With the advent of subcutaneous copper-histidine therapy, the early diagnosis of Menkes disease becomes of utmost importance for patients' prognosis. In the present study, the clinical characteristics of 12 Korean patients with Menkes disease (11 males and 1 female from 11 unrelated families) were described along with the mutation spectrum. Only 2 male patients were diagnosed in the neonatal period, and the other male patients were diagnosed at age 4.3 ± 1.9 months. The presenting signs included depigmented kinky hair, neurologic deficits, and hypotonia. Serum copper and ceruloplasmin levels were markedly decreased. Intracranial vessels were dilated with tortuosity and accompanied by regional cerebral infarctions, even at an early age. Of note, the female patient was diagnosed at age 18 months, during the evaluation for developmental delay, by characteristic MRA findings, biochemical profiles, and genetic evaluation. A total of 11 ATP7A mutations were identified, including five previously unreported mutations. Most mutations were truncated (except 1 missense mutation), including 3 frameshift, 2 nonsense, 3 large deletion, and 2 splice-site variants. The age at commencement of copper-histidine treatment was variable among patients age 7.3 ± 7.5 (0.5-27) months. Despite the treatment, seven patients died before age 5 years, and the remaining patients were severely retarded in neurodevelopment. The poor outcomes of our patients might be related to delayed therapy, but severe ATP7A mutations should be noted as well.

A phase 2 multi-center, open-label, switch-over trial to evaluate the safety and efficacy of Abcertin® in patients with type 1 Gaucher disease.

Gaucher disease is a lysosomal storage disease for which enzyme replacement therapy has proven to be effective. A switch-over clinical trial was performed to evaluate the efficacy and safety of Abcertin® (ISU Abxis, Seoul, Korea) in subjects with type 1 Gaucher disease who were previously treated with imiglucerase. Five Korean patients with type 1 Gaucher disease were enrolled. Previous doses of imiglucerase ranged from 30 to 55 U/kg every other week. The same dose of Abcertin® was administered to all patients for 24 weeks. Primary efficacy endpoints were changes in hemoglobin levels and platelet counts, and the secondary efficacy endpoints included changes in liver and spleen volumes, serum biomarkers, skeletal status and bone mineral density (BMD). During the study period, no statistically significant changes were observed in all parameters including hemoglobin levels and platelet counts, liver and spleen volumes, skeletal status and BMD. Abcertin® administration was continued in three patients for another 24 weeks as an extension of the study. Hemoglobin levels and platelet counts were maintained in all three patients. In conclusion, the efficacy and safety of Abcertin® are similar to those of imiglucerase, and Abcertin® is an effective therapeutic agent for patients with type 1 Gaucher disease (Clinical Trial Registry No. NCT02053896 at www.clinicaltrials.gov).

Allele frequency of a 24 bp duplication in exon 10 of the CHIT1 gene in the general Korean population and in Korean patients with Gaucher disease.

Plasma chitotriosidase activity is used for diagnosis and monitoring of Gaucher disease. However, homozygous duplication of a 24 bp region in exon 10 of the chitotriosidase gene (CHIT1) abolishes enzyme activity, limiting its use as a biomarker in Gaucher disease. This study investigates the allele frequency of the 24 bp duplication, in both the general Korean population and in patients with Gaucher disease. Fifteen Korean patients with Gaucher disease and 231 Korean normal individuals were enrolled. Genotyping was performed to identify the 24 bp duplication in exon 10 of CHIT1 using DNA extracted from peripheral leukocytes or dried blood spots. Two patients with Gaucher disease (13.3%) had normal plasma chitotriosidase activity, and carried a homozygous 24 bp duplication of exon 10 of the CHIT1 gene. Nine patients were heterozygote carriers (60.0%). Of the normal 231 Korean individuals, heterozygous duplication was detected in 109 individuals (47.2%) and homozygous duplication in 75 (32.5%). The allele frequency was 56.1% (95% confidence interval, 49.4-62.7%). The frequency of the 24 bp duplication was remarkably high in both Korean patients with Gaucher disease and in the normal population, limiting the efficacy of chitotriosidase as a biomarker in Gaucher disease in Korea. New biomarkers are required that consider the genetic characteristics of different populations.

Prenatal diagnosis of congenital adrenal hyperplasia due to 21-hydroxylase deficiency through molecular genetic analysis of the CYP21A2 gene.

PURPOSE: Deficiency of 21-hydroxylase (21-OHD) is an autosomal recessively inherited disorder that is characterized by adrenal insufficiency and androgen excess. This study was performed to investigate the clinical utility of prenatal diagnosis of 21-OHD using molecular genetic testing in families at risk. METHODS: This study included 27 pregnant women who had previously borne a child with 21-OHD. Fetal tissues were obtained using chorionic villus sampling (CVS) or amniocentesis. After the genomic DNA was isolated, Sanger sequencing of CYP21A2 and multiplex ligation-dependent probe amplification were performed. The clinical and endocrinological findings were reviewed retrospectively. RESULTS: A total of 39 prenatal genetic tests was performed on 27 pregnant women and their fetal tissues. The mean gestational age at the time of testing was 11.7 weeks for CVS and 17.5 weeks for amniocentesis. Eleven fetuses (28.2%) were diagnosed with 21-OHD. Among them, 10 fetuses (90.9%) harbored the same mutation as siblings who were previously diagnosed with 21-OHD. Among these, 4 fetuses (3 males and 1 female) identified as affected were born alive. All 4 patients have been treated with hydrocortisone, 9α-fludrocortisone, and sodium chloride since a mean of 3.7 days of life. The male patients did not show hyponatremia and dehydration, although they harbored pathogenic variants associated with the salt-wasting type of 21-OHD. CONCLUSION: This study demonstrated the diagnostic efficacy and clinical consequences of diagnosis by prenatal genetic testing in families at risk for 21-OHD. All patients identified as affected were treated with hydrocortisone and 9α-fludrocortisone early after birth, which can prevent a life-threatening adrenal crisis.

Growth trajectories of children born preterm and full term with low birth weight to preschool ages: A nationwide study.

CONTEXT: Preterm (PT) and full term with low birth weight (FT-LBW) children are at a high-risk of poor growth outcomes. OBJECTIVE: To investigate the growth trajectories of PT and FT-LBW children from birth to preschool ages. METHODS: This study included 1,150,508 infants (PT, 41,454; FT-LBW, 38,250) who underwent the first three rounds (4-6, 9-12, and 18-24 months) of the National Health Screening Program for Infants and Children (NHSPIC). Growth measurements were obtained from the NHSPIC database and converted into Z-scores. Growth data at 2, 4, and 6 years old were measured as outcome variables. The impact of being born small on poor growth outcomes was investigated using a generalized estimating equation and Cox proportional-hazards regression analysis. RESULTS: The median birth weights of the PT, FT-LBW, and full term (FT) groups were 2.3, 2.4, and 3.2 kg, respectively. The incidence of short stature (height Z-score < -2 standard deviation score [SDS]) and failure to thrive (FTT) (body mass index (BMI) Z-score < -2 SDS) was the highest in the FT-LBW group, followed by the PT and FT groups. At 4 years old, the incidence rates were 6.0% vs. 5.2% vs. 1.9% for short stature and 4.6% vs. 3.9% vs. 1.7% for FTT. The ß estimate of height outcome was lower in both the PT (-0.326 SDS) and FT-LBW (-0.456 SDS) groups. CONCLUSIONS: The FT-LBW group was consistently shorter and lighter throughout the preschool period than the PT group, highlighting the significance of growth monitoring in high-risk populations.

Impact of Early Diagnostic and Therapeutic Interventions and Clinical Course in Children and Adolescents with Multiple Endocrine Neoplasia Types 1 and 2.

PURPOSE: Multiple endocrine neoplasia types 1 (MEN1) and 2 (MEN2) are inherited endocrine tumor syndromes caused by mutations in the MEN1 or RET genes. This study aimed to investigate clinical outcomes and molecular characteristics among children with MEN. METHODS: This study included eight patients from seven unrelated families. Data on clinical course, biochemical findings, and radiologic studies were collected by retrospective chart review. All diagnoses were genetically confirmed by Sanger sequencing of MEN1 in three MEN1 patients and RET in four patients with MEN2A and one patient with MEN2B. RESULTS: Three patients with MEN1 from two families presented with hypoglycemia at a mean age of 11±2.6 years. Four patients with MEN2A were genetically diagnosed at a mean of 3.0±2.2 years of age by family screening; one of them was prenatally diagnosed by chorionic villus sampling. Three patients with MEN2A underwent prophylactic thyroidectomy from 5 to 6 years of age, whereas one patient refused surgery. The patient with MEN2B presented with a tongue neuroma and medullary thyroid carcinoma at 6 years of age. Subsequently, he underwent a subtotal colectomy because of bowel perforation and submucosal ganglioneuromatosis at 18 years of age. CONCLUSION: This study described the relatively long clinical course of pediatric MEN with a mean follow-up duration of 7.5±3.8 years. Insulinoma was the first manifestation in children with MEN1. Early diagnosis by family screening during the asymptomatic period enabled early intervention. The patient with MEN2B exhibited the most aggressive clinical course.

Long-term endocrine sequelae after hematopoietic stem cell transplantation in children and adolescents.

PURPOSE: As the survival rate from pediatric cancers has increased significantly with advances in treatment modalities, long-term endocrine complications have also risen. This study investigated the frequencies and risks of endocrine sequelae in childhood cancer survivors who received hematopoietic stem cell transplantation (HSCT). METHODS: This study included 200 pediatric patients who underwent HSCT. Clinical and endocrinological findings were collected retrospectively. The median follow-up duration after HSCT was 14 years. RESULTS: Endocrine complications occurred in 135 patients (67.5%). Children who underwent HSCT at pubertal age (n=100) were at higher risk of endocrine complications than those who received it at prepubertal age (79% vs. 56%, P=0.001). The most common complication was hypogonadism (40%), followed by dyslipidemia (22%). Short stature and diabetes mellitus were more prevalent in the prepubertal group, whereas hypogonadism and osteoporosis were more common in the pubertal group. Being female, pubertal age at HSCT, and glucocorticoid use were predictors of an increased risk for any complication. Radiation exposure increased the risk of short stature and hypothyroidism. Hypogonadism was significantly associated with being female, pubertal age at HSCT, and high-dose radiation. Pubertal age at HSCT also increased the risks of osteoporosis and dyslipidemia. CONCLUSION: This study demonstrates that long-term endocrine complications are common after HSCT in children and adolescents. Age at HSCT is a critical factor for endocrine complications after HSCT. These findings suggest that surveillance strategies for endocrine complications in childhood cancer survivors should be specified according to age at HSCT.

Applications of genomic research in pediatric endocrine diseases.

Recent advances in molecular genetics have advanced our understanding of the molecular mechanisms involved in pediatric endocrine disorders and now play a major role in mainstream medical practice. The spectrum of endocrine genetic disorders has 2 extremes: Mendelian and polygenic. Mendelian or monogenic diseases are caused by rare variants of a single gene, each of which exerts a strong effect on disease risk. Polygenic diseases or common traits are caused by the combined effects of multiple genetic variants in conjunction with environmental and lifestyle factors. Testing for a single gene is preferable if the disease is phenotypically and/or geneically homogeneous. Next-generation sequencing (NGS) can be applied to phenotypically and genetically heterogeneous conditions. Genome-wide association studies (GWASs) have examined genetic variants across the entire genome in a large number of individuals who have been matched for population ancestry and assessed for a disease or trait of interest. Common endocrine diseases or traits, such as type 2 diabetes mellitus, obesity, height, and pubertal timing, result from the combined effects of multiple variants in various genes that are frequently found in the general population, each of which contributes a small individual effect. Isolated founder mutations can result from a true founder effect or an extreme reduction in population size. Studies of founder mutations offer powerful advantages for efficiently localizing the genes that underlie Mendelian disorders. The Korean population has settled in the Korean peninsula for thousands of years, and several recurrent mutations have been identified as founder mutations. The application of molecular technology has increased our understanding of endocrine diseases, which have impacted on the practice of pediatric endocrinology related to diagnosis and genetic counseling. This review focuses on the application of genomic research to pediatric endocrine diseases using GWASs and NGS technology for diagnosis and treatment.

Molecular basis and genetic testing strategies for diagnosing 21-hydroxylase deficiency, including CAH-X syndrome.

Congenital adrenal hyperplasia (CAH) is a group of autosomally recessive disorders that result from impaired synthesis of glucocorticoid and mineralocorticoid. Most cases (~95%) are caused by mutations in the CYP21A2 gene, which encodes steroid 21-hydroxylase. CAH patients manifest a wide phenotypic spectrum according to their degree of residual enzyme activity. CYP21A2 and its pseudogene (CYP21A1P) are located 30 kb apart in the 6q21.3 region and share approximately 98% of their sequences in the coding region. Both genes are aligned in tandem with the C4, SKT19, and TNX genes, forming 2 segments of the RCCX modules that are arranged as STK19-C4A-CYP21A1P-TNXA-STK19B-C4B-CYP21A2-TNXB. The high sequence homology between the active gene and pseudogene leads to frequent microconversions and large rearrangements through intergenic recombination. The TNXB gene encodes an extracellular matrix glycoprotein, tenascin-X (TNX), and defects in TNXB cause Ehlers-Danlos syndrome. Deletions affecting both CYP21A2 and TNXB result in a contiguous gene deletion syndrome known as CAH-X syndrome. Because of the high homology between CYP21A2 and CYP21A1P, genetic testing for CAH should include an evaluation of copy number variations, as well as Sanger sequencing. Although it poses challenges for genetic testing, a large number of mutations and their associated phenotypes have been identified, which has helped to establish genotype-phenotype correlations. The genotype is helpful for guiding early treatment, predicting the clinical phenotype and prognosis, and providing genetic counseling. In particular, it can help ensure proper management of the potential complications of CAH-X syndrome, such as musculoskeletal and cardiac defects. This review focuses on the molecular pathophysiology and genetic diagnosis of 21-hydroxylase deficiency and highlights genetic testing strategies for CAH-X syndrome.

Pediatric hepatocellular carcinoma associated with Niemann-Pick disease type C: Case report and literature review.

Niemann-Pick disease type C (NPC) is a rare, autosomal recessive, lysosomal storage disease, resulting from mutations in the cholesterol trafficking proteins NPC1 or NPC2, which is characterized by progressive neurodegeneration and hepatic dysfunction. The hepatic involvement in NPC is usually neonatal cholestasis and hepatosplenomegaly. Only a few cases of severe hepatic complications were reported including acute liver failure, cirrhosis, and hepatocellular carcinoma (HCC). We described the case of a 6-year-old male with NPC with HCC. He had a history of neonatal cholestasis and motor delay. At the age of 6 months, he was diagnosed with NPC, which was confirmed by the detection of a compound heterozygous NPC1 mutation (p.C113Y/p.A927V). He presented recurrent hypoglycemia and abdominal distension. An ultrasound, computed tomography scan, and biopsy revealed that he had a stage IV HCC with pulmonary metastasis. With the literature review and this case, HCC can be a rare fatal comorbid condition in patients with NPC, particularly infantile-onset, male patients with a relatively long disease history, necessitating appropriate HCC surveillance.