Pragmatic Phenotype–Electrophysiology–Genomics Integration in Pediatric Congenital Myasthenic Syndromes: Insights From 36 Patients in a Single‐Center Study in China

Abstract

ABSTRACT Aims To characterize the clinical, electrophysiological, and genetic spectrum of pediatric CMS and evaluate genotype‐informed outcomes using an integrated phenotype–electrophysiology–genomics approach. Methods We retrospectively reviewed 36 pediatric CMS patients evaluated at a single center between 2015 and 2025. Clinical features, RNS, targeted NGS/WES variants, ventilator use, treatments, ACMG/AMP classifications, and MG‐ADL outcomes were analyzed. Results Of 36 patients, 28 (77.8%) developed symptoms in the neonatal period or infancy. Biallelic variants involved 17 CMS genes; postsynaptic CMS was most common (55.6%, 20/36). COLQ and CHRNE were the most frequent genes (13.9%, 5/36 each), followed by CHAT (11.1%, 4/36). VUS were detected in 19 patients (52.8%, 19/36), including 8 with biallelic VUS supported by phenotype, neuromuscular transmission findings, treatment response, and follow‐up. RNS showed a ≥ 10% decrement in 16/21 tested patients (76.2%). CHAT‐CMS was associated with higher ventilator use (3/4 vs. 6/32; p = 0.041) and early mortality (3/4 vs. 1/32; p = 0.002). Median MG‐ADL improved from 5 to 3 after genotype‐informed therapy. Conclusion Pediatric CMS shows marked genetic heterogeneity and frequent VUS‐related uncertainty. Integrating phenotype, electrophysiology, and genomics supports diagnosis and mechanism‐guided therapy. CHAT‐CMS is high risk for early respiratory failure and mortality.