Huntington's disease

Huntington's disease is a degenerative brain disease that causes a host of brain-related complications, including dementia and psychosis, and which is eventually fatal. The condition is a single-gene disorder caused by a slew of added trinucleotide "CAG" repeats on human chromosome 4.

Huntington's disease is an autosomal dominant disorder, meaning that anyone who inherits the condition will display symptoms.