Gene Distribution in Pediatric-Onset Inherited Peripheral Neuropathy: A Single Tertiary Center in Thailand.

BACKGROUND: Inherited peripheral neuropathy presents a diagnostic and therapeutic challenge due to its association with mutations in over 100 genes. This condition leads to long-term disability and poses a substantial healthcare burden on society. OBJECTIVE: This study aimed to investigate the distribution of genes and establish the genotype-phenotype correlations, focusing on pediatric-onset cases. METHODS: Exome sequencing and other analytical techniques were employed to identify pathogenic variants, including duplication analysis of the PMP22 gene. Each patient underwent physical examination and electrophysiological studies. Genotypes were correlated with phenotypic features, such as age at disease onset and ulnar motor nerve conduction velocity. RESULTS: We identified 35 patients with pediatric-onset inherited peripheral neuropathy. Pathogenic or likely pathogenic variants were confirmed in 24 out of 35 (68.6%) patients, with 4 of these variants being novel. A confirmed molecular diagnosis was achieved in 90.9% (10/11) of patients with demyelinating Charcot-Marie-Tooth disease (CMT) and 56.3% (9/16) of patients with axonal CMT. Among patients with infantile-onset CMT (≤2 years), the most common causative genes were MFN2 and NEFL, while GDAP1 and MFN2 were frequent causes among patients with childhood- or adolescent-onset CMT (3-9 years). CONCLUSIONS: The MFN2 gene was the most commonly implicated gene, and the axonal type was predominant in this cohort of Thai patients with pediatric-onset inherited peripheral neuropathy.

Identification of novel mutation in RANKL by whole-exome sequencing in a Thai family with osteopetrosis; a case report and review of RANKL osteopetrosis.

BACKGROUND: Osteopetrosis is a rare form of skeletal dysplasia characterized by increased bone density that leads to bone marrow failure, compressive neuropathy, and skeletal dysmorphism. Molecular diagnosis is essential as it guides treatment and prognosis. We report Thai siblings with an ultra-rare form of osteopetrosis. METHODS: The older brother and the younger sister presented with chronic mandibular osteomyelitis in their 20s. Since childhood, they had visual impairment, pathological fracture, and skeletal dysmorphism. Quadruplet whole-exome sequencing was performed and confirmed with Sanger sequencing. Novel mutation in TNFSF11 (RANKL) c.842T>G, p.Phe281Cys was identified in a homozygous state in both siblings. RESULTS: Surgical debridement, antibiotic, and hyperbaric oxygen therapy were used and discontinued over a 6-month period with normalization of C-reactive protein. Hematopoietic stem cell transplantation candidacy was excluded by molecular diagnosis. CONCLUSION: We report a novel mutation in an ultra-rare form of osteopetrosis. Our siblings manifested with a milder phenotype in comparison with nine cases previously published.

Case series: Childhood Charcot-Marie-Tooth: Predominance of axonal subtype.

Case series reports on clinical features of pediatric hereditary neuropathy in Thailand is scarce. Subtype and clinical presentation in childhood-onset CMT differ from adult-onset. The aim of this study is to investigate the CMT phenotype in Thai children. We retrospectively reviewed children diagnosed with CMT who followed up with Pediatric Neurology, Siriraj Hospital from January 1999 to June 2016. CMT subtypes determined by clinical presentation and neurophysiologic studies. Mutation analysis of PMP22 genes was performed in all demyelinating cases. The disease burden was assessed by CMT Neuropathy Score version 2 (CMTNSv2), CMT Examination Score (CMTES) and CMT Pediatric Scale (CMTPedS). 30 patients from 29 families with Hereditary Neuropathies, 25 diagnosed with CMT and 5 with HSAN. 8-year-old was the average age at first medical visit with disease-related problems. Twenty (67%) were male. Twenty-three were sporadic (77%). 16.7% was autosomal dominant and 6.7% was autosomal recessive. Clinical presentations in CMT children were walking difficulty and foot deformities. Nine (36%) CMT patients had demyelinating and sixteen (64%) had axonal. Forty percent had a history of delayed walking after 15-month-old. Foot deformities presented in all CMT patients, and twelve had foot surgery. 2 axonal CMT patients were wheelchair-dependence. Mean (SD) CMTNSv2, CMTES and CMTPedS were 15.44(9), 11.05(7) and 34(4) respectively. Our findings suggest Thai CMT children are predominantly axonal type. Patients with low socioeconomic status and mild symptoms may not seek healthcare. International collaboration in genetic testing is crucial in diagnosis and initiation of clinical trials in future.

A new syndrome of symphalangism, multiple frenula, postaxial polydactyly, dysplastic ears, dental anomalies, and exclusion of NOG and GDF5.

A Thai girl with a unique combination of limb and craniofacial anomalies is reported. Manifestations include blepharoptosis; prominent nose; hypodontia; multiple, hyperplastic frenula; and dysplastic ears. Limb anomalies include short stature, postaxial polydactyly of both hands and the left foot, proximal and distal symphalangism of fingers, and congenital absence of the distal phalanges of toes 2-5. Mutation analyses of NOG and GDF5, the genes responsible for symphalangism-related syndromes, were negative.