title: Brief report: linkage between G6PD and fragile-X syndrome.
abstract: Eighteen Sardinian pedigrees segregating for the X-fragile site syndrome were studied with respect to the segregation of the fragile site (FS) at Xq28, mental retardation, and macro-orchidism. No exception was found in the association of this symptomatic triad (MOM-X) in 41 out of 42 patients examined. The exceptional individual had micro- rather than macro-orchidism and was found to have a 47, XXY sex chromosome complement. In six informative sibships, the MOM-X syndrome was found to segregate in close linkage association with G6PD-deficiency or protan colorblindness. The maximum likelihood estimate of recombination if 6% with 90% fiducial limits between 2.5 and 19.5% and an odds ratio in favor of measurable linkage of 428:1. However, no hint of measurable linkage was found in six pedigrees segregating for G6PD and the Renpenning syndrome or other unspecified types of X-linked mental retardation. These data give strong support to the generally held hypothesis that the FS at Zq28, characteristic of the MOM-X syndrome, is a direct expression of a genetic change in the same chromosomal region. They also clearly suggest that X-linked MR without FS may be the result of different allelic mutations at the same locus.
mesh_terms: D003117:Color Vision Defects / Q000235:genetics; D005260:Female; D005600:Fragile X Syndrome / Q000201:enzymology / Q000235:genetics*; D008040:Genetic Linkage; D005954:Glucosephosphate Dehydrogenase / Q000235:genetics*; D005955:Glucosephosphate Dehydrogenase Deficiency / Q000235:genetics; D006801:Humans; D007558:Italy; D008297:Male; D011995:Recombination, Genetic; D012729:Sex Chromosome Aberrations / Q000235:genetics*; D013737:Testis / Q000002:abnormalities; D014960:X Chromosome
chemical_list: D005954:Glucosephosphate Dehydrogenase