A strategy to reveal high-frequency RFLPs along the human X chromosome.
Fifteen human X-chromosome-specific DNA fragments, localized to particular regions of that chromosome, were used to search for restriction fragment length polymorphisms. A screening panel prepared by digesting DNA from only two females and one male with 24 restriction enzymes was sufficient to reveal two-allele polymorphisms among one-third of the probes tested. These polymorphisms, as theoretically anticipated, showed minor allele frequencies above 20%, as a rule. Such high-frequency polymorphism allowed identifying females, from pedigrees segregating three X-linked diseases, who were multiply heterozygous for polymorphic loci spread throughout the X chromosome. In addition, two of the 24 enzymes tested with these X-specific probes, Msp I and Taq I, generate fragment sizes in DNA-blotting experiments that, on average, are significantly larger than expected from nearest neighbor predicted recognition site frequencies.
D000483:Alleles; D002874:Chromosome Mapping; D004247:DNA / Q000235:genetics*; D004262:DNA Restriction Enzymes / Q000494:pharmacology*; D004274:DNA, Recombinant; D005260:Female; D005600:Fragile X Syndrome / Q000235:genetics; D005787:Gene Frequency; D006580:Genetic Carrier Screening; D008040:Genetic Linkage; D005819:Genetic Markers; D006801:Humans; D008297:Male; D009136:Muscular Dystrophies / Q000235:genetics; D010375:Pedigree; D011110:Polymorphism, Genetic; D014960:X Chromosome / Q000032:analysis*
D004274:DNA, Recombinant; D005819:Genetic Markers; D004247:DNA; D004262:DNA Restriction Enzymes