LINKAGE STUDY OF CHRONIC CHILDHOOD-ONSET SPINAL MUSCULAR-ATROPHY (SMA) - CONFIRMATION OF CLOSE LINKAGE TO D5S39 IN FRENCH-CANADIAN FAMILIES

Chronic childhood-onset spinal muscular atrophy (SMA) is, after Duchenne muscular dystrophy, the most common neuromuscular disorder in childhood. Recent linkage analyses have mapped this disease to 5q12-5q14. We show that chronic SMA (Types II and III) is tightly linked to the marker locus D5S39 (Zmax = 5.47 at θ{symbol} = 0.02) in eight French Canadian families. In contrast to previously published results, we do not observe close linkage between chronic SMA and D5S6 (Zmax = 0.34 at θ{symbol} = 0.18) or D5S78 (Zmax = 0.25 at θ{symbol} = 0.21). Last, we present a family that appears to be discordant for this localization but may represent the first example of an incompletely penetrant individual. © 1992 Academic Press, Inc. All rights reserved.