Four New Cases of Hypomyelinating Leukodystrophy Associated with the UFM1 c.-155_-153delTCA Founder Mutation in Pediatric Patients of Roma Descent in Hungary

Ufmylation is a relatively newly discovered type of post-translational modification when the ubiquitin-fold modifier 1 (UFM1) protein is covalently attached to its target proteins in a three-step enzymatic reaction involving an E1 activating enzyme (UBA5), E2 conjugating enzyme (UFC1), and E3 ligase enzyme (UFL1). The process of ufmylation is essential for normal brain development and function in humans. Mutations in the UFM1 gene are associated with Hypomyelinating leukodystrophy type 14, presenting with global developmental delay, failure to thrive, progressive microcephaly, refractive epilepsy, and hypomyelination, with atrophy of the basal ganglia and cerebellum phenotypes. The c.-155_-153delTCA deletion in the promoter region of UFM1 is considered to be a founding mutation in the Roma population. Here we present four index patients with homozygous UFM1:c.-155_-153delTCA mutation detected by next-generation sequencing (whole genome/exome sequencing) or Sanger sequencing. This mutation may be more common in the Roma population than previously estimated, and the targeted testing of the UFM1:c.-155_-153delTCA mutation may have an indication in cases of hypomyelination and neurodegenerative clinical course in pediatric patients of Roma descent.