Chromosome 4
Huntington's disease is found to be associated with Chromosome four. The mutation of this gene is an expansion of a nucleotide triplet repeat in the DNA. This genetic effect on chromosome four causes the DNA to actually occur more times then it should. This defect is called the CAG repeat. Normally with this repeat it will occur 10-28 times but with Huntington's disease it occurs 36-120 times. As the triplet number of Cytosine, Adenine and Guanine increase the onset age in the patient will actually decrease. And because the repeat has the chance to lengthen when passed from the parent to child, their chance of inheriting this gene is much higher.
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