Linkage analysis of families with fragile-X mental retardation, using a novel RFLP marker (DXS 304).
A new polymorphic DNA marker U6.2, defining the locus DXS304, was recently isolated and mapped to the Xq27 region of the X chromosome. In the previous communication we describe a linkage study encompassing 16 fragile-X families and using U6.2 and five previously described polymorphic markers at Xq26-q28. One recombination event was observed between DXS304 and the fragile-X locus in 36 informative meioses. Combined with information from other reports, our results suggest the following order of the examined loci on Xq: cen-F9-DXS105-DXS98-FRAXA-DXS304-(DXS52-F8 -DXS15). The locus DXS304 is closely linked to FRAXA, giving a peak lod score of 5.86 at a corresponding recombination fraction of .00. On the basis of the present results, it is apparent that U6.2 is a useful probe for carrier and prenatal diagnosis in fragile-X families.
Dahl
N
N
Department of Medical Genetics, University of Uppsala, Sweden.
Goonewardena
P
P
Malmgren
H
H
Gustavson
K H
KH
Holmgren
G
G
Seemanova
E
E
Annerén
G
G
Flood
A
A
Pettersson
U
U
D002874:Chromosome Mapping; D005260:Female; D005600:Fragile X Syndrome / Q000235:genetics*; D006580:Genetic Carrier Screening; D008040:Genetic Linkage; D005819:Genetic Markers; D006801:Humans; D008297:Male; D010375:Pedigree; D011110:Polymorphism, Genetic; D012150:Polymorphism, Restriction Fragment Length; D011995:Recombination, Genetic; D012729:Sex Chromosome Aberrations / Q000235:genetics*; D014960:X Chromosome
D005819:Genetic Markers