Characterization of Cxorf5 (71-7A), a novel human cDNA mapping to Xp22 and encoding a protein containing coiled-coil α-helical domains

The human X chromosome is known to contain several disease genes yet to be cloned. In the course of a project aimed at the construction of a transcription map of the Xp22 region, we fully characterized a novel cDNA, Cxorf5 (HGMW-approved symbol, alias 71-7A), previously mapped to this region but for which no sequence information was available. We isolated and sequenced the full-length transcript, which encodes a predicted protein of unknown function containing a large number of coiled-coil domains, typically present in a variety of different molecules, from fibrous proteins to transcription factors. We showed that the Cxorf5 cDNA is ubiquitously expressed, undergoes alternative splicing, and escapes X inactivation. Furthermore, we precisely mapped two additional Cxorf5-related loci on the Y chromosome and on chromosome 5. By virtue of its mapping assignment to the Xp22 region, Cxorf5 represents a candidate gene for at least four human diseases, namely spondyloepiphiseal dysplasia late, oral-facial-digital syndrome type 1, craniofrontonasal syndrome, and a nonsyndromic sensorineural deafness.