Spinal and bulbar (bulbospinal) muscular atrophy (BSMA, SBMA, Kennedy's disease) is a progressive motor neuron disease with rare involvement of structures other than the lower motor neuron, such as the endocrine system and the central nervous system (CNS).
Kennedy's disease, also known as bulbospinal muscular atrophy (BSMA), is a rare, adult-onset, X-linked, recessive trinucleotide, polyglutamine (poly-G) disorder, caused by expansion of an unstable CAG-tandem-repeat in exon 1 of the androgen-receptor (AR) gene on chromosome Xq11-12.
Genetic alterations in the AR gene may cause impaired development resulting in androgen insensitivity syndromes (AIS) or in neurodegenerative diseases like Kennedy syndrome.
This fact suggests that the DNA diagnosis by analysis of the androgen receptor gene is very useful to distinguish Kennedy's disease from other forms of BSMA.
We studied androgen receptor function in cultured scrotal skin fibroblasts from eight subjects with X-linked spinal and bulbar muscular atrophy (SBMA) (Kennedy's syndrome) from four families.
However, gene linkage studies indicate proximity of the gene for Kennedy's syndrome and the gene encoding the androgen receptor, which could explain the combination of a motor neuron disorder and the endocrine abnormalities.