Further linkage evidence for localization of mutational sites for nonsyndromic types of X-linked mental retardation at the pericentromeric region

Abstract

We used several microsatellite markers scattered along the X chromosome to search for linkage relationships in a large Sardinian pedigree segregating for nonspecific X‐linked mental retardation (MRX). Markers DXS573 and AR, located at chromosomal subregions Xp11.4–p11.22 and Xq11.2–q12, respectively, were found to segregate in full concordance with the disease, leading to a LOD score of 4.21 at zero recombination value. Recombination with the disease was found with markers MAOB and DXS454 located at Xp11.4–p11.3 and Xq21.1–q22, respectively; accordingly, markers distal to Xp11.4 and Xq22 also segregated independently of the disease. These findings provide strong linkage evidence in favor of the localization of one MRX mutational site in the pericentromeric region of the human X chromosome, justifying the assignment of a new symbol (MRX26) to our pedigree. Finally, on the basis of the recombinational events observed in the Xq21–q22 region, we have been able to refine the assignment of marker DXS456 to Xq21.33–q22. © 1996 Wiley‐Liss, Inc.

XLMR genes: Update 1998

“…Names of cloned genes are indicated in parentheses by the name of the condition, and their localization is underlined. [Gedeon et al, 1996a] MRX1 Xp11.3-q12 [Hu et al, 1994] MRX2 Xp22.2-p21.3 Macrocephaly, square face, macroorchidism, short stature [Gedeon et al, 1991] MRX3 Xq28 - [Hu et al, 1994] MRX4 Xp11.22-q21.3 Speech delay, learning disability [Samanns et al, 1991] MRX5 Xp11.4-q21.2 Speech delay, hyperactivity [Kondo et al, 1991] MRX6 Xq27 Short stature; ''coarse" face; short, broad hands and feet; heterozygote manifestation MRX7 Xp11.23-q12 - MRX8 Xp11.2-q13 - [Willems et al, 1991] MRX9 Xp21.2-q12 - [Gedeon et al, 1996a] MRX10 Xp21.3-p11.4 Hypotelorism, large ears, heterozygote manifestation [Gedeon et al, 1996a] MRX11 Xp21.1-p11.4 Hypotelorism, large ears, heterozygote manifestation [Gedeon et al, 1996a] MRX12 Xp21.2-p11.21 Hypotelorism, large ears, low birth weight, short stature [Kerr et al, 1992] MRX13 Xp22.3-q22.3 Large ears MRX14 Xp11.3-q13.2 - [Raynaud et al, 1996] MRX15 Xp21.1-p11.2 Congenital hypotonia, delayed speech, thin habitus, scoliosis MRX16 Xq28 - [Gedeon et al, 1996a] MRX17 Xp11.2-q12 - [Gedeon et al, 1994a] MRX18 Xp21.1-p11 - [Gedeon et al, 1996a] MRX19 Xp22.3-p22.1 - [Lazzarini et al, 1995] MRX20 Xp11.4-q21.3 - [Kozak et al, 1993] MRX21 Xp22.3-p21.1 Heterozygote manifestation [Passos-Bueno et al, 1993] MRX22 Xp21.1-p21.31 Hypotonia, incontinence, severe generalized muscle atrophy [Gregg et al, 1996] MRX23 Xq23-q24 - [Martinez et al, 1995] MRX24 Xp22.32-p22.2 Slightly ''corase" face, small head circumference [Nordstrom et al, 1992] MRX25 Xq27.3-qter Heterozygote manifestation [Robledo et al, 1996] MRX26 Xp11.3-q21.33 - [Gedeon et al, 1996b] MRX27 Xq23-q26.3 Growth failure, mutism, seizures, brachycephaly, square face [Holinski-Feder et al, 1996] MRX28 Xq28 - [Hane et al, 1996] MRX29 Xp22.12-p11.4 - [Donnelly et al, 1996] MRX30 Xq21.33-q23 - [Donnelly et al, 1996] MRX31 Xp11.23-q13 - [Hane et al, 1999] MRX32 Xp22.2-p21.3 - [Holinski-Feder et al, 1996] MRX33 X...…”

Letter to the editor: How many X-linked genes for non-specific mental retardation (MRX) are there?

“…comrnun.) Moraine et al, 1994Moraine et al, 1994 This studyd Gedeon et al, 1994a This study' Lazzarini et al, 1995Kozak et al, 1993Passos-Bueno et al, Not known Martinez et al, 1995Nordstrom et al, 1992Robledo et al, 1996Gedeon et al, 1996 Holinski-Feder et al, Hane et al, 1995Donnelly et al, 1996Donnelly et al, 1996Hane et al, 1996 Update of Suthers et al [1988] and Kerr et al [ Update of Arveiler et al [1988]. Update of Kerr et al [1992].…”