Clinical and Genetic Characteristics Associated With Survival Outcome in Late-Onset Huntington's Disease in South Korea.

BACKGROUND AND PURPOSE: The onset of Huntington's disease (HD) usually occurs before the age of 50 years, and the median survival time from onset is 15 years. We investigated survival in patients with late-onset HD (LoHD) (age at onset ≥60 years) and the associations of the number of mutant CAG repeats and age at onset (AAO) with survival in patients with HD. METHODS: Patients with genetically confirmed HD at six referral centers in South Korea between 2000 and 2020 were analyzed retrospectively. Baseline demographic, clinical, and genetic characteristics and the survival status as at December 2020 were collected. RESULTS: Eighty-seven patients were included, comprising 26 with LoHD (AAO=68.77±5.91 years, mean±standard deviation; 40.54±1.53 mutant CAG repeats) and 61 with common-onset HD (CoHD) (AAO=44.12±8.61 years, 44.72±4.27 mutant CAG repeats). The ages at death were 77.78±7.46 and 53.72±10.86 years in patients with LoHD and CoHD, respectively (p<0.001). The estimated survival time was 15.21±2.49 years for all HD patients, and 10.74±1.95 and 16.15±2.82 years in patients with LoHD and CoHD, respectively. More mutant CAG repeats and higher AAO were associated with shorter survival (hazard ratio [HR]=1.05, 95% confidence interval [CI]=1.01-1.09, p=0.019; and HR=1.17, 95% CI=1.03-1.31, p=0.013; respectively) for all HD patients. The LoHD group showed no significant factors associated with survival after disease onset, whereas the number of mutant CAG repeats had a significant effect (HR=1.12, 95% CI=1.01-1.23, p=0.034) in the CoHD group. CONCLUSIONS: Survival after disease onset was shorter in patients with LoHD than in those with CoHD. More mutant CAG repeats and higher AAO were associated with shorter survival in patients with HD.

Clinical and genetic characteristics of three patients with congenital insensitivity to pain with anhidrosis: Case reports and a review of the literature.

BACKGROUND: Congenital insensitivity to pain with anhidrosis (CIPA) is an extremely rare autosomal recessive disorder caused by loss-of-function mutations of the NTRK1 gene, affecting the autonomic and sensory nervous system. Clinical manifestation is varied and includes recurrent fever, pain insensitivity, anhidrosis, self-mutilating behavior, and intellectual disability. METHODS: Clinical and genetic features were assessed in two males and one female with genetically confirmed CIPA using exome or genome sequencing. RESULTS: CIPA symptoms including recurrent fever, pain insensitivity, and anhidrosis manifested at the age of 1 year (age range: 0.3-8 years). Two patients exhibited self-mutilation tendencies, intellectual disability, and developmental delay. Four NTRK1 (NM_002529.3) mutations, c.851-33T>A (p.?), c.2020G>T (p.Asp674Tyr), c.2303C>T (p.Pro768Leu), and c.574-156_850+1113del (exons 5-7 del) were identified. Two patients exhibited early onset and severe phenotype, being homozygous for c.851-33T>A (p.?) mutations and compound heterozygous for c.851-33T>A (p.?) and c.2020G>T (p.Asp674Tyr) mutation of NTRK1. The third patient with compound heterozygous mutations of c.2303C>T (p.Pro768Leu) and c.574-156_850+1113del (exons 5-7 del) displayed a late onset and milder clinical manifestation. CONCLUSION: All three patients exhibited variable phenotypes and disease severity. This research enriches our understanding of clinical and genetic aspects of CIPA, highlighting variable phenotypes and disease severity.

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.

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.

Lesch-Nyhan syndrome: a case report.

Lesch-Nyhan syndrome (LNS) is a rare X-linked recessive disorder caused by a mutation in the hypoxanthine phosphoribosyltransferase 1 (HPRT1) gene. This syndrome is characterized by excessive production of uric acid, mental retardation, self-mutilation, choreoathetosis, and spasticity. The most distinctive symptom is compulsive self-mutilation. For patients with LNS, different methods have been tried to reduce self-biting behaviors including restraints, behavioral treatment, medications, deep brain stimulation, tooth extraction and botulinum toxin A injection. In this report, we present a case of LNS undergoing cheiloplasty due to self-mutilation and tooth extraction of the left deciduous maxillary canine.

Clinical Characteristics and Long-Term Outcomes of Adrenal Tumors in Children and Adolescents.

OBJECTIVE: Adrenal tumors are generally rare in children and can be a part of familial cancer syndrome. This research was conducted to examine the clinical outcomes, histopathological results, and genetic etiologies of adrenal tumors in children and adolescents. METHODS: Thirty-one children and adolescents with adrenal tumors were included. Data on clinical outcomes and endocrine and radiologic results were retrospectively analyzed. Molecular analysis was conducted in select patients according to their phenotype and family history. RESULTS: The median age at diagnosis was 7.9 years (range: 0.8-17.8 years) with 5.1±1.8 cm of maximum tumor diameter. Adrenal adenoma (n=7), carcinoma (n=5), borderline (n=2), isolated micronodular adrenocortical disease (n=2), pheochromocytoma (n=8), paraganglioma (n=3), and ganglioneuroma (n=4) are all pathological diagnoses. The most common presenting symptom was excess production of adrenocortical hormones (n=15), including virilization and Cushing syndrome. Non-functioning adrenocortical tumors were found in a patient with congenital adrenal hyperplasia. Genetic etiologies were identified in TP53 (n=5), VHL (n=4), and PRKACA (n=1). Patients with mutations in TP53 were young (1.5±0.5 years) and had large masses (6.1±2.3 cm). CONCLUSIONS: This study describes clinical outcomes and the pathological spectrum of adrenal tumors in children and adolescents. Adrenocortical tumors mostly presented with an excess of the adrenocortical hormone. Patients with genetic defects presented at a young age and large size of tumors, necessitating genetic testing in patients at a young age.

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.

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

Objective: 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. Methods: 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). Results: Seven patients (four patients with KS, one patient with nIHH, one prepubertal boy with anosmia, and one newborn patient) from six 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. Conclusions: 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.

Clinical outcomes and genotype-phenotype correlations in patients with complete and partial androgen insensitivity syndromes.

PURPOSE: Androgen insensitivity syndrome (AIS) is a rare X-linked recessive disorder caused by unresponsiveness to androgens because of mutations in the AR gene. Here, we investigated the clinical outcomes and molecular spectrum of AR variants in patients with AIS attending a single academic center. METHODS: This study included 19 patients with AIS who were confirmed by molecular analysis of AR. Clinical features and endocrinological findings were retrospectively collected, including presenting features, external genitalia, sex of rearing, timing of gonadectomy, pubertal outcomes, and sex hormone levels. Molecular analysis of AR was performed using Sanger, targeted gene panel, or whole-exome sequencing. RESULTS: Among all 19 patients, 14 (74%) were classified as having complete AIS (CAIS), whereas 5 (26%) had partial AIS (PAIS). All patients with CAIS, and 3 patients with PAIS were reared as female. One patient with CAIS manifested a mixed germ cell tumor at the age of 30 years. Molecular analysis of AR identified 19 sequence variants; 12 (63%) were previously reported, and the remaining 7 (37%) were novel. Missense mutations were the most common type (12 of 19, 63%), followed by small deletions, nonsense mutations, an insertion, and a splice site mutation. CONCLUSION: Here, we describe the clinical outcomes and molecular characteristics of 19 Korean patients with AIS. Patients with PAIS manifested various degrees of masculinization of the external genitalia. Nonsense and frameshift mutations were frequent in patients with CAIS, whereas patients with PAIS harbored exclusively missense mutations.

KBG syndrome: Clinical features and molecular findings in seven unrelated Korean families with a review of the literature.

BACKGROUND: KBG syndrome is a rare genetic disorder involving macrodontia of the upper central incisors, craniofacial, skeletal, and neurologic symptoms, caused either by a heterozygous variant in ANKRD11 or deletion of 16q24.3, including ANKRD11. Diagnostic criteria were proposed in 2007 based on 50 cases, but KBG syndrome remains underdiagnosed. METHODS: Whole exome sequencing (WES) and array comparative genomic hybridization (array CGH) were conducted for genetic analysis and patient phenotypes were characterized based on medical records. RESULTS: Eight patients from seven unrelated families were confirmed with KBG syndrome. All patients (8/8, 100%) had some degree of craniofacial dysmorphism and developmental delay or intellectual disabilities. Triangular face, synophrys, anteverted nostril, prominent ears, long philtrum, and tented upper lip, which are typical facial dysmorphism findings in patients with KBG syndrome, were uniformly identified in the eight patients participating in this study, with co-occurrence rates of 4/8 (50%), 4/8 (50%), 4/8 (50%), 4/8 (50%), 5/8 (62.5%), and 5/8 (62.5%), respectively. Various clinical manifestations not included in the diagnostic criteria were observed. Six patients had point mutations in ANKRD11, one had an exonic deletion of ANKRD11, and one had a 16q24.3 microdeletion. According to the ACMG guidelines, all mutations were classified as pathogenic. The c.2454dup (p.Asn819fs*1) mutation in Pt 4 was reported previously. The remaining variants (c.397 + 1G>A, c.226 + 1G>A, c.2647del (p.Glu883Argfs*94), and c.4093C>T (p.Arg1365Ter)) were novel. CONCLUSION: The clinical and molecular features of eight patients from seven unrelated Korean families with KBG syndrome described here will assist physicians in understanding this rare genetic condition.

Deciphering Epigenetic Backgrounds in a Korean Cohort with Beckwith-Wiedemann Syndrome.

Background: Beckwith-Wiedemann syndrome (BWS) is a congenital overgrowth disorder caused by genetic or epigenetic alterations at two imprinting centers (ICs) in the 11p15.5 region. Delineation of the molecular defects is important for prognosis and predicting familial recurrence. We evaluated epigenetic alterations and potential epigenotype-phenotype correlations in Korean children with BWS. Methods: Forty children with BWS with proven genetic or epigenetic defects in the 11p15.5 region were included. The phenotype was scored using the BWS consensus scoring system. Methylation-specific multiplex ligation-dependent probe amplification (MS-MLPA), bisulfite pyrosequencing, a single-nucleotide polymorphism microarray, and CDKN1C sequencing were used for confirmative diagnosis. Results: Patients met the criteria for genetic testing, with a mean clinical score of 5.4±2.0. Methylation alterations were consistent between MS-MLPA and bisulfite pyrosequencing in all patients. Twenty-six patients (65.0%) had IC2 loss of methylation (IC2-LoM), 11 (27.5%) had paternal uniparental disomy (patUPD), and one (2.5%) had IC1 gain of methylation. Macroglossia and external ear anomalies were more common in IC2-LoM than in patUPD, and lateralized overgrowth was more common in patUPD than in IC2-LoM (all P<0.05). Methylation levels at IC2 were inversely correlated with birth weight standard deviation score (r=-0.476, P=0.014) and clinical score (r=-0.520, P=0.006) in the IC2-LoM group. Conclusions: Comprehensive molecular analysis of the 11p15.5 region revealed epigenotype-phenotype correlations in our BWS cohort. Bisulfite pyrosequencing can help clarify epigenotypes. Methylation levels were correlated with fetal growth and clinical severity in patients with BWS.

Clinical and genetic features of four patients with Pearson syndrome: An observational study.

ABSTRACT: Pearson syndrome (PS) is a multisystem mitochondrial cytopathy arising from deletions in mitochondrial DNA. Pearson syndrome is a sporadic disease that affects the hematopoietic system, pancreas, eyes, liver, and heart and the prognosis is poor. Causes of morbidity include metabolic crisis, bone marrow dysfunction, sepsis, and liver failure in early infancy or childhood. Early diagnosis may minimize complications, but suspicion of the disease is difficult and only mitochondrial DNA gene testing can identify mutations. There is no specific treatment for PS, which remains supportive care according to symptoms; however, hematopoietic stem cell transplantation may be considered in cases of bone marrow failure.We herein describe the clinical and genetic characteristics of four patients with PS. One patient presented with hypoglycemia, two developed pancytopenia, and the final patient had hypoglycemia and acute hepatitis as the primary manifestation. All patients had lactic acidosis. Additionally, all patients showed a variety of clinical features including coagulation disorder, pancreatic, adrenal, and renal tubular insufficiencies. Two patients with pancytopenia died in their early childhood. Our experience expands the phenotypic spectrum associated with PS and its clinical understanding.

Unfavorable clinical outcomes in patients with carbamoyl phosphate synthetase 1 deficiency.

PURPOSE: Carbamoyl phosphate synthetase 1 (CPS1) deficiency affects the first step of urea cycle and is a severe form of urea cycle disorder (UCD). The severity of hyperammonemic encephalopathy determines the clinical course of UCDs. Here, we describe the genetic and clinical characteristics of CPS1 deficiency in Korea. PATIENT AND METHODS: This study included seven patients with CPS1 deficiency genetically confirmed from January 1992 to September 2020. The peak ammonia level during the first crisis, the half time of peak ammonia level, the initial plasma amino acid levels, and neurological outcomes were compared between CPS1 deficiency and two common UCDs (i.e., 17 patients with argininosuccinate synthetase 1 deficiency and 24 patients with ornithine transcarbamylase deficiency). RESULT: Eleven CPS1 mutations were identified, including 10 novel mutations. Eight mutations were missense. Six patients with CPS1 deficiency had neonatal type. The peak ammonia level, initial glutamate level, and accompanying rate of irreversible neurological damages were highest in patients with CPS1 deficiency. The patient with late-onset CPS1 deficiency responded dramatically to N-carbamylglutamate treatment. CONCLUSION: The clinical manifestations of CPS1 deficiency were the most severe among UCDs. Considering the high proportion of missense mutations, responsiveness to N-carbamylglutamate would be evaluated in a future study.

Phenotypic spectrum of patients with mutations in CHD7: clinical implications of endocrinological findings.

Objective: Heterozygous CHD7 mutations cause a broad spectrum of clinical phenotypes ranging from typical CHARGE syndrome to self-limited delayed puberty. This study aimed to investigate the clinical characteristics of endocrine dysfunction in patients with CHD7 mutations. Methods: The clinical features and endocrine findings from 30 patients with CHD7 variants were retrospectively reviewed. A diagnosis of CHARGE syndrome was based on the Verloes diagnostic criteria. Results: Seventeen patients fulfilled the criteria for typical CHARGE syndrome, one patient for partial/incomplete CHARGE, and the remaining eleven patients had atypical CHARGE syndrome. One patient was diagnosed with Kallmann syndrome and unilateral deafness. The most frequently observed features were inner ear anomalies (80.0%), intellectual disability (76.7%), and external ear anomalies (73.3%). The mean height and weight SDSs at diagnosis were -2.6 ± 1.3 and -2.2 ± 1.8, respectively. Short stature was apparent in 18 patients (60%), and 1 patient was diagnosed with growth hormone deficiency. Seventeen males showed genital hypoplasia, including micropenis, cryptorchidism, or both. Seven patients after pubertal age had hypogonadotropic hypogonadism with hyposmia/anosmia and olfactory bulb hypoplasia. Truncating CHD7 mutations were the most common (n = 22), followed by missense variants (n = 3), splice-site variants (n = 2), and large deletion (n = 2). Conclusions: A diverse phenotypic spectrum was observed in patients with CHD7 variants, and endocrine defects such as short stature and delayed puberty occurred in most patients. Endocrine evaluation, especially for growth and pubertal impairment, should be performed during diagnosis and follow-up to improve the patient's quality of life.

Genotype-phenotype correlations and long-term efficacy of pamidronate therapy in patients with osteogenesis imperfecta.

PURPOSE: Osteogenesis imperfecta (OI) is a rare bone fragility disorder caused by defects in type 1 collagen biosynthesis. This study investigated the genotype-phenotype correlations and the efficacy of pamidronate therapy in patients with OI in a single academic center. METHODS: This study included 24 patients with OI. A clinical scoring system was used to evaluate disorder severity. COL1A1 and COL1A2 genes were analyzed in 13 patients using Sanger sequencing. Genotype-phenotype correlations and the efficacy of pamidronate therapy were analyzed through a retrospective medical chart review. RESULTS: Of the 24 patients, 18 (75%) were classified as type I (12 with type Ia and 6 with type Ib), 2 as type III (8.4%), and 4 as type IV (16.7%). Type Ia patients showed relatively higher lumbar bone mineral density (BMD) standard deviation scores (SDS) and lower clinical scores than those with other types. Seven patients with qualitative mutations had lower lumbar BMD-SDS (P=0.015) and higher clinical scores (P=0.008) than 6 patients with quantitative mutations. The annual fracture frequency and lumbar BMD-SDS improved in patients with qualitative mutations after pamidronate treatment. CONCLUSION: This study demonstrated that OI patients with qualitative mutations in COL1A1/2 had a more severe phenotype than those with quantitative mutations. Patients with qualitative mutations showed a significant reduction in fracture frequency and an increase in lumbar BMD-SDS after pamidronate treatment. Clinical score and genotype might be helpful for predicting phenotype and response to pamidronate therapy in OI patients.

Case Report: Mevalonic Aciduria Complicated by Acute Myeloid Leukemia After Hematopoietic Stem Cell Transplantation.

Mevalonic aciduria (MA) is the most severe clinical subtype of mevalonate kinase deficiency (MKD) caused by an inherited defect in the mevalonate pathway. The treatment of MKD focuses on the suppression of recurrent hyperinflammatory attacks using anti-inflammatory drugs. Recently, allogeneic hematopoietic stem cell transplantation (HCT) was shown to successfully ameliorate autoinflammatory attacks in patients with MKD. Here, we report a case of an infant who showed severe recurrent systemic inflammation and was diagnosed with MA. Although she responded to steroids, her symptoms relapsed after the dose was tapered, and organ deterioration occurred. Therefore, at the age of 11 months, HCT from a matched, unrelated donor was performed for curative treatment. However, at 50 days after transplantation, acute myeloid leukemia was diagnosed, which was chemo-refractory. A second HCT from her haploidentical father was performed to treat the acute myeloid leukemia, but the patient died of sepsis on day 4 after transplantation. This is the first report of malignancy following HCT for MA. Our findings suggest that normalizing the mevalonate pathway after HCT in patients with MKD impacts patients differently depending on the clinical spectrum and severity of disease.

Phenotypic and molecular spectra of patients with switch/sucrose nonfermenting complex-related intellectual disability disorders in Korea.

BACKGROUND: The switch/sucrose nonfermenting (SWI/SNF) complex is an adenosine triphosphate-dependent chromatin-remodeling complex associated with the regulation of DNA accessibility. Germline mutations in the components of the SWI/SNF complex are related to human developmental disorders, including the Coffin-Siris syndrome (CSS), Nicolaides-Baraitser syndrome (NCBRS), and nonsyndromic intellectual disability. These disorders are collectively referred to as SWI/SNF complex-related intellectual disability disorders (SSRIDDs). METHODS: Whole-exome sequencing was performed in 564 Korean patients with neurodevelopmental disorders. Twelve patients with SSRIDDs (2.1%) were identified and their medical records were retrospectively analyzed. RESULTS: ARID1B, found in eight patients, was the most frequently altered gene. Four patients harbored pathogenic variants in SMARCA4, SMARCB1, ARID2, and SMARCA2. Ten patients were diagnosed with CSS, and one patient without a typical phenotype was diagnosed with ARID1B-related nonsyndromic intellectual disability. Another patient harboring the SMARCA2 pathogenic variant was diagnosed with NCBRS. All pathogenic variants in ARID1B were truncating, whereas variants in SMARCA2, SMARCB1, and SMARCA4 were nontruncating (missense). Frequently observed phenotypes were thick eyebrows (10/12), hypertrichosis (8/12), coarse face (8/12), thick lips (8/12), and long eyelashes (8/12). Developmental delay was observed in all patients, and profound speech delay was also characteristic. Agenesis or hypoplasia of the corpus callosum was observed in half of the patients (6/12). CONCLUSIONS: SSRIDDs have a broad disease spectrum, including NCBRS, CSS, and ARID1B-related nonsyndromic intellectual disability. Thus, SSRIDDs should be considered as a small but important cause of human developmental disorders.

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.

Clinical and molecular spectra of BRAF-associated RASopathy.

Noonan syndrome (NS) and cardio-facio-cutaneous (CFC) syndrome are the most common subtypes of RASopathy. As an effector of Ras, BRAF is one of the molecules responsible for RASopathy. We investigated the phenotypic and genotypic features of 26 patients with BRAF-associated RASopathy. The clinical diagnoses were CFC (n = 21, 80.8%), NS (n = 3, 11.5%), NS/CFC (n = 1, 3.8%), and undefined syndromic intellectual disability (ID) (n = 1, 3.8%). The mostly shared phenotypes were ID (90.5%), cutaneous manifestations (84.6%), congenital heart defects (76.9%), short stature (76.9%), and dysmorphic features such as short neck (65.4%) and low-set ears (65.4%). Importantly, moderate to severe ID (57.1%) and epilepsy (26.9%) were noted. Eighteen different missense mutations were found, including a novel mutation, p.Phe498Tyr. p.Gln257Arg (n = 9, 34.6%) was the most common mutation, and the mutations were clustered in the cysteine-rich domain or protein kinase domain. A review of previously reported cases along with our findings revealed the existence of multiple sub-phenotypes of RASopathy within a single genotype, indicating that BRAF-associated RASopathy is not variant-specific. Our study further delineated the diverse and expanded clinical phenotypes of BRAF-associated RASopathy with their molecular genetic characteristics.

Aberrant expression of PAX6 gene associated with classical aniridia: identification and functional characterization of novel noncoding mutations.

The PAX6 is essential for ocular morphogenesis and is known to be highly sensitive to changes in gene expression, where neither over- nor under-expression ensures normal ocular development. Two unrelated probands with classical aniridia who were previously considered "PAX6-negative", were studied by whole-genome sequencing. Through the use of multiple in silico deep learning-based algorithms, we identified two novel putative causal mutations, c.-133_-132del in the 5' untranslated region (5'-UTR) and c.-52 + 5G>A in an intron upstream of the PAX6 gene. The luciferase activity was significantly increased and VAX2 binding was disrupted with the former 5'-UTR variant compared with wild-type sequence, which resulted in a striking overexpression of PAX6. The minigene assay showed that the c.-52 + 5G>A mutation caused defective splicing, which resulted in the formation of truncated transcripts.