SMN GENE ANALYSIS OF THE SPINAL FORM OF CHARCOT-MARIE-TOOTH-DISEASE

The spinal form of Charcot-Marie-Tooth disease (spinal CMT) is a rare genetic disorder of the peripheral nervous system, the genetic basis o f which remains unknown. To test the hypothesis that a defect of survi val motor neuron (SMN), the determining gene for spinal muscular atrop hy (SIMA), would result in spinal CMT, 18 unrelated spinal CMT patient s were studied. Nine of them were sporadic cases and the other nine be longed to unrelated autosomal dominant pedigrees. None of the 18 patie nts showed deletions involving SMN exons 7 or 8, the most frequent gen e alteration found in SMA, In addition, haplotype analysis in two larg e autosomal dominant pedigrees showed that the 5q13 locus was not segr egating with the spinal CMT locus. Therefore, neither the sporadic nor the familial cases of spinal CMT are associated with a SMN gene delet ion, nor are the familial cases linked to the 5q13 region, indicating that this neuropathy is genetically different from SMA.