Detection of CAG trinucleotide repeat numbers with fragment analysis in patients diagnosed with Huntington's disease and in their families

Purpose: Huntington's Disease (HD) is an autosomal dominant disorder affecting nervous system. CAG trinucleotide repeat (TNR) increase in Huntingtin gene causes the disease. In normal individuals, 10-35 TNRs are found whereas in HD this number exceeds 36-37. This study aimed to investigate TNR numbers in individuals with HD diagnosed family and to provide genetic counselling for individuals with abnormal alleles. Materials and Methods: Subjects consist of family members of a male who died at age of 60 due to HD. Randomly selected 57 healthy individuals are also analysed for control. TNR numbers were determined by fragment analysis. Results: TNR numbers of family members were determined as 17, 21, 23, 25, 33, 36 and 39. TNR numbers of randomly selected healthy people were found below 26. Individuals with 33 and 36 TNRs were considered as risk groups. Individuals with 39 TNRs were considered as HD patients. Conclusion: Since some subjects had 39 TNRs, it was emphasized that these people should be under physician control. Prenatal diagnosis is recommended to those who plan to have children. In addition, subjects with 33 and 36 CAG trinucleotide repeats are advised to inform new generations about HD and that they may be affected in future.