Cloning and characterization of DXS6673E, a candidate gene for X-linked mental retardation in Xq13.1

In several families with non-specific X-linked mental retardation (XLMR)linkage analyses have assigned the underlying gene defect to thepericentromeric region of the X chromosome, but none of these genes havebeen isolated so far. Here, we report on the cloning and characterizationof a novel gene, DXS6673E, that maps to Xq13.1, is subject toX-inactivation and is disrupted in the 5' untranslated region by a balancedX;13 translocation in a mentally retarded female. The DXS6673E gene ishighly conserved among vertebrates and its expression is most abundant inbrain. It encodes a hydrophilic protein of 1358 amino acids (aa) that doesnot show sequence homology to other known proteins. A segment of thisprotein consisting of neutral and hydrophobic aa with a proline residue inevery second position may represent a transmembrane domain. Almost completesequence identity was found between the 3' end of the DXS6673E gene and twoexpressed sequence tags (ESTs) and between the 5' end of the DXS6673E geneand a third EST. Moreover, weaker sequence similarity was observed betweencoding regions and two other ESTs.