Brief report: linkage between G6PD and fragile-X syndrome

• Published in: American journal of medical genetics Vol. 15; no. 1; p. 113
• Main Authors: Filippi, G, Rinaldi, A, Archidiacono, N, Rocchi, M, Balazs, I, Siniscalco, M
• Format: Journal Article
• Language: English
• Published: United States 01.05.1983
• Subjects: Color Vision Defects - genetics; Female; Fragile X Syndrome - enzymology; Fragile X Syndrome - genetics; Genetic Linkage; Glucosephosphate Dehydrogenase - genetics; Glucosephosphate Dehydrogenase Deficiency - genetics; Humans; Italy; Male; Recombination, Genetic; Sex Chromosome Aberrations - genetics; Testis - abnormalities; X Chromosome; Italy
• ISSN: 0148-7299
• DOI: 10.1002/ajmg.1320150115

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.