A novel homozygous mutation of GJC2 derived from maternal uniparental disomy in a female patient with Pelizaeus-Merzbacher-like disease

Abstract

Pelizaeus-Merzbacher-like disease (PMLD) is an autosomal recessive hypomyelinating disorder of the central nervous system characterized by nystagmus, motor developmental delay, ataxia, and progressive spasticity. The gap junction protein gamma-2 gene (GJC2), encoding the gap junction protein connexin 47, is one of the genes responsible for this condition. In this study, a novel homozygous mutation in GJC2 (c.746C>G; p.P249R) was identified in a 21-year-old female patient with PMLD. Although her mother was a carrier of this mutation, the Mendelian inheritance pattern could not be determined because the paternal sample was unavailable. Alternatively, chromosomal microarray testing together with single nucleotide polymorphism typing (CGH+SNP) was performed to determine the gene copy number and analyze the haplotype in the 1q42.13 region in which GJC2 is located. The result showed no deletion, but the GJC2 region was involved in the loss-of-heterozygosity region. Furthermore, haplotype of chromosome 1, in which GJC2 is located, revealed that both copies of chromosome 1 were derived from the patient's mother, indicating maternal uniparental disomy of chromosome 1. This study showed the advantage of the SNP genotyping microarray for detecting the origin of the mutation.