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First genetic disease mapped, Huntington’s Disease

Huntington’s Disease

First genetic disease mapped, Huntington’s Disease

Huntington’s disease (HD) causes the death of specific neurons in the brain, leading to jerky movements, physical rigidity, and dementia. Symptoms usually appear in midlife and worsen progressively. The location of the HD gene, whose mutation causes Huntington’s disease, was mapped to chromosome 4 in 1983, making HD the first disease gene to be mapped using DNA polymorphisms – variants in the DNA sequence. The mutation consists of increasing repetitions of “CAG” in the DNA that codes for the protein huntingtin. The number of CAG repeats may increase when passed from parent to child, leading to earlier HD onset in each generation. The gene was finally isolated in 1993.
1983