X-CHROMOSOMAL BULBOSPINAL NEURONOPATHY (X -BSN, KENNEDY SYNDROME) - ADISORDER WITH REPETITIVE TRIPLET SEQUENCES - CASE-STUDIES, DIFFERENTIAL-DIAGNOSIS AND MOLECULAR-GENETIC ASPECTS

X-chromosomal recessive bulbospinal neuronopathy (X-BNS, Kennedy's dis ease) is an important differential diagnosis of amyotrophic lateral sc lerosis. We present the data of ten own patients along with a review o f the literature on this uncommon disease which is caused by an expand ed GAG-repeat in the androgen receptor gene. This mutation probably af fects the transcription regulating activity of the androgen receptor i n neurons. Signs and symptoms of X-BSN can be derived from partial ins ensitivity for androgens and a mixed, mainly motor neuronopathy. The c linical diagnosis is based on: 1. lower motor neuron weakness of bulba r and proximal limb muscles with onset in the third to fifth decade, 2 . cramps and pronounced fasciculations, particularly of facial muscles , 3. postural tremor, 4. diminished or absent sensory action potential s inspite of only minor sensory impairment, 5. gynecomastia, and 6. in fertility, diabetes mellitus and hyperlipoproteinemia in a minority of cases. Unlike amyotrophic lateral sclerosis, disease progression is s low with barely shortened life expectancy, which should be stressed in patient counselling. Causal treatment is as yet unavailable but sever al aspects of palliative medicine should be considered.