X-linked bulbar and spinal muscular atrophy, or Kennedy disease: Clinical, neurophysiological, neuropathological, neuropsychological and molecular study of a large family

We report the clinical, neurophysiological, neuropsychological, neuropathological and molecular findings in a large family with X-linked bulbar and spinal muscular atrophy (X-BSMA). Molecular study, performed in 28 family members, showed an increase in the number of CAG repeats in 6 affected males (including 2 presymptomatic patients), and in 10 females, of whom 5 were obligate carriers. All symptomatic patients showed, besides the typical manifestation of X-BSMA, neurophysiological signs of sensory nerve involvement, and abnormal findings in neuropsychological tests. Sural nerve biopsy, performed in two patients, was consistent with axonal atrophy and slow-rate degeneration, with secondary demyelination. Neurophysiological alterations were also present in 6 out of 8 carriers, consisting of neurogenic EMG changes in 3 cases and abnormal sensory action potentials (SAP) and reduced conduction velocity of the sural nerve in 3 cases. Abnormalities of at last two neuropsychological tests were found in 6 out of 8 carriers. Alterations of the sensory nerves in X-BSMA patients have been previously reported in some cases; however, we demonstrate for the first time sensory nerve involvement also in carriers. Evidence of central nervous system involvement, with neuropsychological impairment in all symptomatic patients and in some carriers, is another feature of this family, not previously reported in X-BSMA. In spite of the variable phenotypic features, the number of CAG repeats ranged from 40 to 44 in the affected patients, indicating that phenotypic expression was not related to the size of the mutation, but was probably age-related.