Screening of autosomal recessive Charcot-Marie-Tooth (ARCMT2), distal hereditary motor neuropathy (dHMN) and hereditary spastic paraplegia (HSP) patients for mutations in axonal neuropathy genes

Abstract

Charcot-Marie-Tooth Disease (CMT), distal Hereditary Motor Neuropathy (HMN) and Hereditary Spastic Paraplegia (HSP) constitute the largest group of inherited diseases affecting the peripheral nervous system. In the scope of this thesis, the genetic background of autosomal recessive CMT2 disease was investigated in a cohort of Turkish families and isolated cases. For this purpose, GDAP1 and LMNA genes were investigated by SSCP analyses, and linkage to 19q13.1 locus was tested by homozygosity mapping. The study was extended to screening of the small heat shock protein genes, HSPB1, and HSPB8, that have been recently shown to be responsible for autosomal dominant CMT2 and distal HMN. The involvement of another heat shock protein gene, HSP60, was screened for mutations in a small group of Hereditary Spastic Paraplegia patients. Exclusion of all known loci responsible for ARCMT2 in a family demonstrated that there is at least one more locus responsible for the disease phenotype. Only one of the CMT4 patients was found to be mutated in GDAP1. Another causative mutation was identified in HSPB1 in a CMT2 patient. Clinical diagnoses of the patients were found to be compatible with the genetical diagnoses. All other patients tested negative for mutations in the GDAP1, LMNA, HSPB1, HSPB8, and HSP60 genes although several novel or previously repoted polymorphisms were detected. Absence of mutations in these patients indicated that the contribution of these genes to the appropriate disease phenotypes is low in the Turkish population. v