Mental Retardation, X-Linked 58

A number sign (#) is used with this entry because nonsyndromic X-linked mental retardation-58 is caused by mutation in the TM4SF2 gene (TSPAN7; 300096) on chromosome Xp11.

Clinical Features

Holinski-Feder et al. (1999) described an Austrian family with nonsyndromic X-linked mental retardation. The 5 affected males in the family had mild to moderate mental retardation and no consistent dysmorphic features, while obligatory carrier females were normal.

Mapping

By linkage analysis in an Austrian family with nonsyndromic X-linked mental retardation, Holinski-Feder et al. (1999) mapped the disorder locus to an X pericentromeric location, with flanking markers DXS989 and DXS1111, with a maximum multipoint lod score of 2.09.

Molecular Genetics

In the affected family reported by Holinski-Feder et al. (1999), Abidi et al. (2002) identified a 2-bp deletion (300096.0003) in the TM4SF2 gene, resulting in a premature stop codon and truncated protein.

In 2 unrelated families with nonspecific X-linked mental retardation, Zemni et al. (2000) identified mutations in the TM4SF2 gene (300096.0001-300096.0002).

Da Costa Maranduba et al. (2004) identified a mutation in the TM4SF2 gene (300096.0002) in a 21-year-old male with mental retardation. His mother and sister, both of normal intelligence, were found to be carriers of the mutation, but not his mentally normal brother.