A novel intronic mutation in the DDP1 gene in a family with X-linked dystonia-deafness syndrome.

BACKGROUND X-linked dystonia-deafness syndrome (Mohr-Tranebjaerg syndrome) is a rare neurodegenerative disease characterized by hearing loss and dystonia. So far, 7 mutations in the coding region of the DDP1 gene have been described. They consist of frameshift, nonsense, missense mutations or deletions. OBJECTIVE To investigate the presence of mutations in the DDP1 gene in a family with dystonia-deafness syndrome. DESIGN Seven members belonging to 2 generations of a family with 2 affected subjects underwent genetic analysis. Mutational screening in the DDP1 gene was made through DNA direct sequencing. RESULTS We found an intronic mutation in the DDP1 gene. It consists of an A-to-C substitution in the position -23 in reference to the first nucleotide of exon 2 (IVS1-23A>C). The mutation was present in 2 affected men and their respective unaffected mothers, whereas it was absent in the healthy men from this family and in 90 healthy controls. CONCLUSIONS Intronic mutations in the DDP1 gene can also cause X-linked dystonia-deafness syndrome. In our case, the effect of the mutation could be due to a splicing alteration.