ANTICIPATION AND TRINUCLEOTIDE-EXPANSION IN JUVENILE HUNTINGTONS-DISEASE

Huntington's disease (HD) is an autosomal dominant disorder usually pr esenting in the third or fourth decade of life. In rare cases it may o ccur in childhood. Advanced age of onset and increasing severity of si gns in subsequent generations have been found in juvenile HD and are d escribed as anticipation. We report a 12-year old boy who developed HD at four years of age while his father and further members of the fath er's family developed the disease at the age of thirty. By using a mod ified polymerase chain reaction we investigated the number of GAG-repe ats in the HD-gene of both the patient and his father. The HD-gene of the father contained 53 GAG-repeats whereas the HD-gene of our patient showed 94 GAG-repeats (normal value 11-34 repeats). The expansion of the number of GAG-repeats matches the clinical observation of anticipa tion and offers a molecular explanation of this phenomenon.