The mapping of chromosome 4q markers in relation to facioscapulohumeral muscular dystrophy (FSHD)

Abstract

Four DNA markers on the distal long arm of chromosome 4 have been analyzed for their linkage relationship to facioscapulohumeral muscular dystrophy (FSHD) in a series of 23 families with this disease. Two hypervariable markers, pH30 (D4S139) and EFD 139.1 (D4S184), both show close linkage with the disorder, with a maximum recombination fraction (theta max) of .02 and a maximum lod score (Zmax) of 36.77 and 34.50, respectively; two other markers, the locus for factor XI (F11) and the microsatellite marker Mfd22 (D4S171), both show less close linkage, with respective theta max of .16 (Zmax = 3.40) for F11 and .24 (Zmax = 1.61) for D4S171. While the relative ordering and orientation of the loci on the chromosome remain provisional, analysis of 15 individual recombination events in seven families supports the order D4S171-F11-D4S184-D4S139-FSHD, with the disease locus telomeric to all four markers.