A novel mutation in the GDAP1 gene is associated with autosomal recessive Charcot-Marie-Tooth disease in an Amish family

Charcot-Marie-Tooth disease (CMT) constitutes a large group of genetically heterogeneous disorders of the peripheral nervous system. Autosomal recessive forms of CMT are less common in the general population but account for the vast majority of CMT phenotypes in communities with a high prevalence of consanguinity. At least 10 genetic loci cause autosomal recessive forms of CMT. Mutations in the ganglioside-induced differentiation-associated protein 1 (GDAP1) gene are among the most frequent genetic causes of autosomal recessive forms of CMT. To date, 28 mutations in GDAP1 gene have been linked with the disease. Here, we report a novel GDAP1 mutation in an Old Order Amish family with CMT. To ascertain the Amish CMT locus, we performed a genome-wide single nucleotide polymorphism (SNP) analysis on one of three patients from a consanguineous pedigree. Assuming mutation homogeneity, the analysis sought large homozygous SNP blocks that also contained known CMT loci. The largest homozygous SNP block in the patient was localized to chromosome 8q13.1-21.3 and contained the GDAP1 gene. Sequence analysis revealed a novel homozygous mutation, c.692C > T, at codon 231 (p.P231L) in exon 5 of GDAP1 in all patients. Neither the unaffected individuals in the family nor the healthy control samples were homozygous for this mutation. Our findings suggested that this novel mutation in GDAP1 gene is associated with an autosomal recessive form of CMT in Ohio Old Order Amish community.