Linkage relationships between DXS105, DXS98, and other polymorphic DNA markers flanking the fragile X locus.
We report on linkage data between DXS105, DXS98, the locus for the fragile X syndrome (FRAXA), and 3 other polymorphic loci that flank the FRAXA locus. An analysis was undertaken to determine the relative positions of DXS105 and DXS98 and to test the assignment of DXS105 to a location proximal and closely linked to FRAXA. In this study of fragile X fra(X) syndrome families, the DXS105 locus was calculated to be proximal to FRAXA with a maximum lod score of 10.36 at theta = 0.08. DXS105 was also shown to be closely linked to the gene for factor IX (F9)(Z = 11.84 at theta = 0.08) and to DXS98 (Z = 4.91 at theta = 0.04). The order of the loci proximal to FRAXA is most likely centromere-factor IX-DXS105-DXS98-FRAXA-telomere. The use of DXS105 and DXS98 in clinical investigations should significantly increase the accuracy of risk assessment in informative fragile X families.
Carpenter
N J
NJ
Chapman Research Institute of Medical Genetics, Children's Medical Center, Tulsa, Oklahoma 74135.
Thibodeau
S N
SN
Brown
W T
WT
D002874:Chromosome Mapping; D015342:DNA Probes; D005600:Fragile X Syndrome / Q000235:genetics*; D005819:Genetic Markers; D006801:Humans; D008126:Lod Score; D010375:Pedigree; D012150:Polymorphism, Restriction Fragment Length; D012306:Risk; D014960:X Chromosome
D015342:DNA Probes; D005819:Genetic Markers