MUTILATING NEUROPATHIC ULCERATIONS IN A CHROMOSOME 3Q13-Q22 LINKED CHARCOT-MARIE-TOOTH DISEASE TYPE 2B FAMILY

Background-Charcot-Marie-Tooth disease type 2 (CMT2) or hereditary mot or and sensory neuropathy type II (HMSN II) is an inherited axonal neu ropathy of the peripheral nervous system. Three autosomal dominant CMT 2 loci have been located on chromosomes 1p35-p36 (CMT2A), 3q13-q22 (CM T2B), and 7p14 (CMT2D) indicating that CMT2 is a genetically heterogen eous disorder. Methods-A CMT2 family was examined for linkage to the C MT2A, CMT2B, and CMT2D loci using short tandem repeat polymorphisms. R esults-Suggestive evidence for linkage to 3q13-q22 was found. Recombin ations occurred with markers D3S1769 and D3S1267 indicating that the C MT2B locus is located distal to D3S1267 and resides in an interval of 25 cM. Some patients in this family have pronounced sensory disturbanc es leading to poorly healing ulcerations. Conclusions-These unusual se nsory signs for CMT were also noted in the only other CMT2B family rep orted so far, suggesting a distinct clinical phenotype for CMT2B. Excl usion of the locus for hereditary sensory neuropathy type I (HSN I) on chromosome 9q22 indicates that HSN I with mild motor symptoms and CMT 2 with prominent sensory abnormalities are not allelic.