Gene localization was determined by linkage analysis in 5 families with non-specific X-linked mental retardation (MRX) and were MRX1, Xp11.4-q21.31; MRX10, Xp21.3-p11.4; MRX11, Xp21.3-p11.22; MRX12, Xp21.3-q21.1; and MRX13, Xp22.3-q21.22.
Mutations of the Interleukin-1-receptor accessory protein like 1 (IL1RAPL1) gene are associated with cognitive impairment ranging from non-syndromic X-linked mental retardation to autism.
We also analyzed ACSL4 and DLG3, which have previously been known to cause XLMR and IL1RAPL2, a homologous gene for IL1RAPL1 that is mutated in autism and XLMR.
By systematically sequencing 737 genes (annotated in the Vertebrate Genome Annotation database) on the human X chromosome in 250 families with X-linked mental retardation, we identified mutations in the UPF3 regulator of nonsense transcripts homolog B (yeast) (UPF3B) leading to protein truncations in three families: two with the Lujan-Fryns phenotype and one with the FG phenotype.
These observations contribute to the phenotypic knowledge of patients with PQBP1 mutations and make this XLMR syndrome well recognizable to clinicians.
Thorough investigation of an MRX critical region in Xp22.1-21.3 enabled us to identify a new gene expressed in brain that is responsible for a non-specific form of X-linked mental retardation.
Renpenning syndrome (also known as "MRXS8"; gene RENS1, MIM 309500) shares phenotypic manifestations with several other XLMR syndromes, notably the Sutherland-Haan syndrome.
Here we report on the localization of a presumptive MRX gene to chromosomal region Xq24-q26 in a German family with nonspecific X-linked mental retardation (MRX 75, HUGO Human Gene Nomenclature Committee).
ATRX is a member of the Snf2 family of chromatin-remodelling proteins and is mutated in an X-linked mental retardation syndrome associated with alpha-thalassaemia (ATR-X syndrome).
Mutation of the ATRX gene leads to X-linked alpha-thalassemia/mental retardation (ATR-X) syndrome and several other X-linked mental retardation syndromes.
Novel truncating mutations in the polyglutamine tract binding protein 1 gene (PQBP1) cause Renpenning syndrome and X-linked mental retardation in another family with microcephaly.
Mutations in the polyglutamine tract binding protein 1 gene (PQBP1) have recently been reported in four XLMR disorders (Renpenning, Hamel cerebro-palato-cardiac, Sutherland-Haan, and Porteous syndromes) as well as in several other families.