Molecular Genetics
For 10 years, scientists focused on a segment of chromosome 4 and, in 1993, finally isolated the HD gene. The process of isolating the responsible gene—motivated by the desire to find a cure—was more difficult than anticipated. Scientists now believe that identifying the location of the HD gene is the first step on the road to a cure.
Finding the HD gene involved an intense molecular genetics research effort with cooperating investigators from around the globe. In early 1993, the collaborating scientists announced they had isolated the unstable triplet repeat DNA sequence that has the HD gene. Investigators relied on the NINDS-supported Research Roster for Huntington's Disease, based at Indiana University in Indianapolis, to accomplish this work. First started in 1979, the roster contains data on many American families with HD, provides statistical and demographic data to scientists, and serves as a liaison between investigators and specific families. It provided the DNA from many families affected by HD to investigators involved in the search for the gene and was an important component in the identification of HD markers.
For several years, NINDS-supported investigators involved in the search for the HD gene made yearly visits to the largest known kindred with HD—14,000 individuals—who live on Lake Maracaibo in Venezuela. The continuing trips enable scientists to study inheritance patterns of several interrelated families.
The HD Gene and Its Product