[Huntington's disease: molecular basis and detection of carriers]

Huntington's disease (HD) results from extensive damage to the nerve cells of the brain cortex and basal ganglia. The gene associated with these changes was mapped in 1983 to the short arm of chromosome 4, at 4p16.3. A decade later it was cloned and the mutation was identified as an increase in the number of CAG repeats in the coding sequence. In the normal gene there are up to 34 repeats but in HD there are more than 36. This is termed dynamic mutation and is found in several other diseases, most of which manifest neurological symptoms. We summarize our studies of 10 families with HD, and 20 individuals with no known history of the disease. Our studies suggest that Jewish patients with HD exhibit the same dynamic gene mutation found in non-Jews. The number of repeats, both in diseased patients and normal controls, is similar to that found in non-Jews. Paternal inheritance was associated with increased severity of symptoms and earlier clinical manifestation, similar to what has been reported. Our experience testing for Huntington gene mutations indicates that this is a relatively simple, reliable and accurate test which can be used in the diagnosis of the disease, in identifying carriers, and for prenatal diagnosis.