Leukocyte telomere lenght in Huntington's Disease. A study in fully penetrant and reduced penetrant alleles

Introduction. Huntington's Disease (HD), an autosomal dominant neurodegenerative disease, is caused by an expanded CAG repeat in the first exon of HTT gene. The disease is fully penetrant in individuals with 40 or more CAG repeats, and reduced penetrance in the range of 36-39 repeats. Overall the age at onset, usually at midlife, inversely correlates with the number of CAG repeats, and severity of symptoms vary widely between individuals. In the present study, we investigated the relationship between Leukocyte Telomere Length (LTL) and disease progression. Methods. LTL (T/S ratio) was measured in manifest HD patients (HD, n=62) and pre-manifest HD patients (pre-HD, n=38) with fully penetrant alleles, in subjects with reduced penetrant alleles (rp-HD, n=23), and age-matched controls (n= 76). Results. Mean LTL values of controls, pre-HD and HD patients were significantly different (p< 0.0001), in the order: HD (0.58 ± 0.07)