Difficult diagnosis of the fragile X syndrome made possible by direct detection of DNA mutations.
Genetic recombination near the fragile X locus (Xq27.3) has frequently been a problem in linkage studies of families in which the fragile X is segregating. This case report illustrates the resolution of a difficult situation in a fragile X family for whom cytogenetic studies were inconclusive and where recombination had twice confounded attempts at prenatal DNA diagnosis by RFLP analysis. Using a newly developed DNA probe, StB12.3, for direct detection of DNA instability in the fragile X locus, the presence of the fragile X was ascertained definitively in a prenatal DNA sample.
Greenwood Genetic Center, DNA Diagnostic Laboratory, South Carolina 29646.
J
J
Tarleton
S
S
Wong
D
D
Heitz
C
C
Schwartz
D015139:Blotting, Southern; D004247:DNA / Q000235:genetics; D015342:DNA Probes / Q000235:genetics*; D005260:Female; D005600:Fragile X Syndrome / Q000175:diagnosis*; D008040:Genetic Linkage / Q000235:genetics; D006801:Humans; D008297:Male; D009154:Mutation / Q000235:genetics; D010375:Pedigree; D012150:Polymorphism, Restriction Fragment Length; D011296:Prenatal Diagnosis / Q000379:methods*
D015342:DNA Probes; D004247:DNA