[The DNA test in the diagnosis of Huntington disease].
Huntington's disease is the most prominent basal ganglion disease. Huntington's gene, IT15, in chromosome 4p16.3, has 67 axons with 10,366 bp coding space and unstable CAG sequence that codes glutamine on 5' terminal. The molecular-genetic analysis of disease determined expansion of nucleotide repeated CAG sequences. In large Bosnian family with Huntington's disease specific DNA diagnosis of IT15 gene mutation is performed, according the wishes of one female member with "high genetic risk", that voluntarily accessed to DNA test in order to make plans for her own family "without risk" of pathologic gene transmission. A mutation in IT15 gene (number of CAG tandem repeats 46, size of DNA fragment 165 bp and 245 bp) is detected in DNA of her clinically affected brother. But, results of PCR analysis of her DNA sample showed 23 CAG tandem repeats (fragment size 180 bp) that excluded presence of Huntington's disease. We accentuate importance of DNA test in persons with "genetic risk", that are not gene carriers. In that case there are able to create own future without fear of pathological gene transmission.