Analysis of HTT CAG repeat expansion in Italian patients with amyotrophic lateral sclerosis

HTT full-penetrance pathogenic repeat expansions, the genetic cause of Huntington's disease (HD), have been recently reported in a minority of frontotemporal dementia/amyotrophic lateral sclerosis (ALS) patients (0.13%). We analyzed HTT CAG repeats in an Italian cohort of ALS patients (n = 467) by repeat-primed polymerase chain reaction. One patient harbored two expanded alleles in the HTT gene (42 and 37 CAG repeats). The absence of HD typical symptoms and the clinical picture consistent with ALS, corroborated by the diagnostic assessment, apparently excluded a misdiagnosis of HD.

Automated summary

Recent studies have found that full-penetrance pathogenic repeat expansions of the HTT gene exist in a minority of frontotemporal dementia/amyotrophic lateral sclerosis (ALS) patients. In an analysis of ALS patients in Italy, one patient was found to have two expanded alleles of the HTT gene. This patient did not exhibit typical symptoms of Huntington's disease (HD) and had a clinical presentation consistent with ALS, ruling out a misdiagnosis of HD.