Carrier detection of the fragile X syndrome with flanking RFLP markers and linkage analysis.
Linkage analysis was performed in 34 fragile X (fra(X)) families in order to study the efficiency of carrier detection using the restriction fragment length polymorphisms (RFLPs) closely linked to fra(X) locus (FRAXA). The marker loci used were F9, DXS105, DXS98, DXS369, DXS297 and DXS477 proximally and DXS465, DXS296, DXS304, DXS52 and F8C distally to FRAXA. Flanking heterozygosity was achieved in 60% of the females with a combination of 3 restriction enzymes and 6 closest RFLP markers. When adding more distant markers and other restriction enzymes to the analysis, the proportion of females heterozygous for flanking polymorphisms increased to 96%. With RFLP-analysis most (85/91) females at high risk of being a carrier could be separated clearly into 2 groups: those with a very low and those with a very high risk. The 6 cases with a recombination between flanking markers did not benefit from RFLP-analysis.
Department of Clinical Genetics, Oulu University Central Hospital, Finland.
M L
ML
Väisänen
M
M
Kähkönen
J
J
Leisti
D004247:DNA / Q000235:genetics; D015342:DNA Probes; D005260:Female; D005600:Fragile X Syndrome / Q000175:diagnosis* / Q000235:genetics; D006580:Genetic Carrier Screening; D008040:Genetic Linkage; D005819:Genetic Markers; D006801:Humans; D008297:Male; D012150:Polymorphism, Restriction Fragment Length
D015342:DNA Probes; D005819:Genetic Markers; D004247:DNA