ANALYSIS OF THE (CAG)N REPEAT AT THE IT15 LOCUS IN A POPULATION FROM CALABRIA (SOUTHERN ITALY)

The defect causing Huntington's disease (HD) has recently been discove red as an expanded CAG trinucleotide repeat located at the 5' end of t he IT15 gene. This discovery allows the molecular diagnosis of HD by m easuring the CAG repeat length. The normal and pathological repeat ran ges in a population need to be established before a diagnostic test fo r HD can be performed. To determine the distribution of IT15 alleles i n a population from Calabria (southern Italy), we analyzed 102 normal subjects and 9 HD patients coming from a defined area of Calabria (pro vince of Cosenza), Expanded alleles ranged from 44 to 76 repeats. Norm al alleles varied from 8 to 27 repeats, which is one of the lowest val ues observed at the top of the normal range; the mean was significantl y different from the value observed in six other populations, The alle le distribution seemed to group mainly around the mode, and no interme diate alleles were present in our sample, These results suggest a part icular stability of the CAG repeat at the IT15 locus in the Calabrian group and confirm once again the peculiar genetic structure of this po pulation.