NUMBER OF TRIPLET REPEATS IN FRENCH FAMIL IES WITH HUNTINGTONS-DISEASE

IT15 is a recently discovered gene that encodes a protein named huntin gtine. A polymorphic CAG repeat in the open reading frame proposed for IT15 has been characterized. An increase in the number of these repea ts has been correlated with Huntington's disease. CAG repeats in the h untingtine gene were studied in 85 different French families with Hunt ington's disease. In 79 patients from 60 families, length of the repet itive fragment ranged from 37 to 100 units, versus 11 to 35 units for normal chromosomes. A negative correlation was found in 72 affected in dividuals between the length of the repetitive fragment and age at ons et of symptoms (r=0.51, p<10(-4)).