Huntington's disease (HD) is an autosomal dominant neurodegenerative disorder. 
The causative mutation is an expansion of more than 36 CAG repeats in the first 
exon of IT15 gene. Many studies have shown that the IT15 interacts with several 
modifier genes to regulate the age at onset (AO) of HD. Our study aims to 
investigate the implication of CAG expansion and 9 modifiers in the age at onset 
variance of 15 HD Tunisian patients and to establish the correlation between 
these modifiers genes and the AO of this disease. Despite the small number of 
studied patients, this report consists of the first North African study in 
Huntington disease patients. Our results approve a specific effect of modifiers 
genes in each population.