Novel TMEM63A mutation associated with transient hypomyelination of infancy - lessons from a previously negative whole-exome sequencing case: Three case reports

BACKGROUND Hypomyelinating leukodystrophies are rare neurodevelopmental disorders characterized by impaired myelin development and early motor delay. Hypomyelinating leukodystrophy type 19 (HLD-19), also termed transient hypomyelination of infancy, is caused by TMEM63A variants. It can clinically resemble other hypomyelinating leukodystrophies but is distinguished by developmental improvement. However, its phenotypic spectrum remains incompletely defined. CASE SUMMARY We describe 3 related indiv