Androgen receptor gene polymorphisms in amyotrophic lateral sclerosis.

Amyotrophic lateral sclerosis (ALS) is more common in men than in women (male to female ratio of approximately 2:1), suggesting a role for a sex-linked factor in the disease. The recent identification of a mutation of the androgen receptor gene in Kennedy's disease or X-linked bulbospinal neuronopathy, a rare form of progressive lower motor neurone degeneration, also associated with clinical signs of androgen insensitivity, raises the possibility that androgen function may be disturbed in other motor neurone disorders, including ALS. The Kennedy's disease mutation consists of an increased size of a highly polymorphic CAG repeat sequence in the first exon of the androgen receptor gene, coding for a polyglutamine tract. We have analysed this CAG repeat sequence in a large number of patients with typical sporadic ALS and in normal controls, in order to test the hypothesis that this polymorphism of the androgen receptor gene may influence susceptibility for ALS. We report that the distribution of alleles relating to the size of the CAG repeat sequence of the androgen receptor gene is similar in ALS and controls, indicating that polymorphisms of the CAG repeat sequence of the androgen receptor gene play a limited role, if any, in susceptibility to ALS.