DHX30-Associated Neurodevelopmental Disorder with Severe Motor Impairment and Absent Language: First Korean Case in Two Siblings and Literature Review.

DHX30 variants have recently been reported in patients with neurodevelopmental disorders with severe motor impairment and absent language (NEDMIAL). We report the first Korean siblings presenting with NEDMIAL and previously unreported clinical features harboring a rare de novo DHX30 missense variant. The proband was a 10-year-old boy presenting with intellectual disability with severe motor impairment, absent language, facial dysmorphism, strabismus, sleep disturbances, and feeding difficulties. We performed whole-exome sequencing using genomic deoxyribonucleic acid isolated from buccal swabs, which revealed a heterozygous missense variant of DHX30: (c.2344C>T, p.Arg782Trp). Sanger sequencing was conducted for the proband, the affected sister, and each parent. The same variant was confirmed in two siblings but not in their parents, suggesting the possibility of de novo germline mosaicism.