Kennedy's disease is caused by specific mutations of the androgen receptor gene which is found on the proximal long arm of the X chromosome.
In patients with Kennedy's disease, the androgen receptor gene has an increase in the number of CAG repeats within its coding region.
It is thought that, unlike testicular feminisation, where all androgen receptor function is lost, Kennedy's disease results from partial inactivation of the androgen receptor. Motor neurones appear more sensitive to this defect than other tissues.
Last reviewed 01/2018