A new polymorphic DNA marker RN1, defining locus DXS369, was recently isolated. Using different somatic cell hybrids, RN1 was mapped between markers 4D-8 and U6.2. We have narrowed the localization of RN1 to the region between 4D-8 and FRAXA by genetic mapping in fragile X [fra(X)] families. Combined with information from other reports, the following order of loci on Xq27-q28 is suggested: cen-F9-(DXS105- DXS152)-DXS98-DXS369-FRAXA-DXS304-(DXS52-DXS15-F8)-tel. The locus DXS369 is closely linked to FRAXA, with a peak lodscore of 18.5 at a recombination fraction of 0.05. Therefore, RN1 is a useful probe for carrier detection and prenatal diagnosis in fra(X) families.

flanking DNA markers, fragile X, genetic mapping
dx.doi.org/10.1002/ajmg.1320380233, hdl.handle.net/1765/65200
American Journal of Medical Genetics
Department of Clinical Genetics

Oostra, B.A, Majoor-Krakauer, D.F, van Hemel, J.O, Bakker, E, Callen, D.F, Schmidt, M.M, & van Oost, B.A. (1991). Mapping of a new RFLP marker RN1 (DXS369) close to the fragile site FRAXA on Xq27-q28. In American Journal of Medical Genetics (Vol. 38, pp. 332–335). doi:10.1002/ajmg.1320380233