REGIONAL LOCALIZATION OF AN X-LINKED MENTAL-RETARDATION GENE TO XP21.1-XP22.13 (MRX38)

A gene responsible for X-linked mental retardation with macrocephaly a nd seizures (MRX38) in a family with five affected males in three gene rations was localized to Xp21.1-p22.13 by linkage analysis. Recombinat ion events placed the gene between DXS1226 distally and DXS1238 proxim ally, defining an interval of approximately 14 cM. A peak lod score of 2.71 was found with several loci in Xp21.1 (DXS992, DXS1236, DXS997, and DXS1036) at a recombination fraction of zero. The map intervals of 5 X-linked mental retardation loci, MRX2 (Xp22.1-p22.2), MRX19 (Xp22) , MRX21 (Xp21.1-p22.3), MRX29 (Xp21.2-p22.1), and MRX32 (Xp21.2-p22.1) , and two syndromal mental retardation loci, Partington syndrome (PRTS ; Xp22) and Coffin-Lowry syndrome (CLS; Xp22.13-p22.2), overlap this r egion. As none of these display the same phenotype seen in the family reported here, this X-linked mental retardation locus may represent a new entity. (C) 1996 Wiley-Liss, Inc.