Analysis of CAG repeat expansion in Huntington's disease gene (IT 15) in a Hungarian population

Huntington's disease (HD) is a neurodegenerative disorder with autosomal dominant inheritance. The genetic defect is a CAG trinucleotide repeat expansion at the 5' end of the IT 15 gene on chromosome 4. This gene has not been analyzed in the Hungarian population yet. To obtain data DNA from 26 HD patients, 18 members of their families and 70 normal controls was amplified in the involved region by polymerase chain reaction. The CAG repeat numbers varied from 37 to 70 (median: 43) in HD patients and asymptomatic carriers, while individuals of the normal control group had 10-36 CAG repeat numbers (median: 18). The length of CAG repeat expansion in Hungarian HD patients was similar to that reported from other countries. The group of normal controls had the same CAG repeat expansion as populations reported from Western European countries. It is a useful piece of data for population genetics to prove that the population of Hungary is a mélange of different nations that influenced the history of the country in the last 11 centuries. As opposed to this, the only closely related nation, the Finnish, was genetically more isolated during this time, so the frequency of HD (and also the number of CAG repeats in normal individuals) proved to be exceptionally low.