Gene
The 5' end of the HD gene has a sequence of three DNA bases, cytosine-adenine-guanine (CAG), coding for the amino acid glutamine, that is repeated multiple times. This region is called a trinucleotide repeat. Normal persons have a CAG repeat count of between seven and 35 repeats.
The HD gene is located on the short (p) arm of chromosome 4 at position 16.3, from base pair 3,113,411 to base pair 3,282,655.
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