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Chin Med J (Taipei) 1998;61:S155.

Kennedy's Disease: Genetic Diagnosis of an Inherited Form of Motor Neuron Disease

Bing-Wen Soong

The Neurological Institute, Veterans General Hospital-Taipei, Taipei, Taiwan, R.O.C.


Kennedy's disease (X-linked spinal and bulbar muscular atrophy) is an inherited form of motor neuron disease that may be diagnosed genetically using the polymerase chain reaction (PCR). This form of motor neuron disease principally affects the proximal limb girdle muscles, as well as those involved with deglutition and phonation. Onset is usually late, in the fourth to fifth decades of life, and progression is slow. Moderate gynecomastia and testicular atrophy are usually present, suggesting a defect in androgen receptor function. Being inherited in an X-linked recessive manner, only males are affected, with females as the unaffected carriers,. The genetic abnormality that causes Kennedy's disease is an enlargement of the androgen receptor (AR) gene, which is located on the proximal long arm of the X chromosome. In patients with this disease, a region in the gene containing repeated CAG triplet nucleotides is approximately twice the size of that found in normal people. Using PCR to amplify this region of the AR gene, we confirmed this genetic mutation in 10 males from different families. Five heterozygote females, the daughters of affected males and carrier females, were also identified. In addition, there were 5 asymptomatic mutant gene carriers. Each has a 50% chance of inheriting the abnormal gene from his mother and thus developing Kennedy's disease.

[Chin Med J (Taipei) 1998;61:S155.]

Copyright: 1998, Chinese Medical Association (Taipei)