Further evidence of genetic heterogeneity in autosomal dominant distal motor neuronopathy

Abstract

Distal hereditary motor neuronopathy (distal HMN) is a genetically and clinically heterogeneous disorder. To date three loci have been identified on chromosomes 7p14, 9q34 and 12q24. We describe a four generation Italian family with distal HMN starting at around 30 years of age with weakness and atrophy of distal leg muscles and pyramidal features. We performed genetic linkage analysis with microsatellites on chromosomes 7p14, 9q34 and 12q24. Negative LOD scores excluded any evidence of linkage to the above‐mentioned chromosomes in the family. Moreover, because of pyramidal features in our patients, we performed the linkage analysis to all the known loci for autosomal dominant hereditary spastic paraparesis (ADHSP). The analysis was negative thus excluding that our patients were affected by a complicated form of ADHSP. These data further confirm a genetic heterogeneity within inherited motor neuronopathy disorders.