The Cause of Huntington's Disease
inherited as an autosomal dominant disorder

resulting from a mutation on chromosome 4.

expansion of CAG repeats at the end of the gene.

the gene product (the protein huntintin) is not fully understood

it is known to be expressed ubiquitously and needed for normal cell survival.

huntinin mutation leads to inappropriate apoptosis, and destruction of cells.

ACh neuron death at cerebral cortex

Why this cell destruction is differentially targeted to the basal ganglia and cerebral cortex is not understood.