SCREENING OF DOMINANTLY INHERITED CHARCOT-MARIE-TOOTH NEUROPATHIES

Sixty-three families with dominantly inherited Charcot-Marie-Tooth (CM T) neuropathies including 730 subjects (total) from which 356 affected were studied clinically, electrophysiologically (MNCVs and EMGs), by genetic linkage, and screened for DNA duplication. Thirty-eight famili es (60.3%) were type 1A (demyelinating CMT mapped on chromosome 17). D NA duplication was present in 36 families (94.8% of CMT1A families). O ne CMT1A family (2.6%) showed no duplication but suggested genetic lin kage with markers of chromosome 17. One CMT1A family (2.6%) revealed n onduplication in some affected members and duplication in other affect ed members. The disease in that family segregated with the same chromo some 17 markers regardless of duplication status. The other CMT famili es with dominant inheritance but without duplication included one fami ly with CMT1B (demyelinating CMT mapped on chromosome 1) (1.6%), 14 fa milies with CMT2 axonal neuropathy (22.2%), and 10 families with X-lin ked dominant CMT (15.9%). (C) 1993 John Wiley & Sons, Inc.