Sequence characterization of a newly identified human alpha-tubulin gene (TUBA2)

We report on the isolation and initial characterization of a human alpha-tubulin gene named TUBA2. This gene is located in the 13q11 region and has been considered a candidate gene for two nonsyndromic deafnesses, DFNB1 and DFNA3. The gene, with a minimum size of 6.5 kb, contains five exons and four introns starting at codon positions 1, 76, 125, and 352, one of which is inserted between the initiation methionine codon and the codon specifying the second amino acid, arginine 2. Neither rearrangement nor point mutation was found in the coding region of the gene in DFNB1- and DFNA3-affected patients. The gene was therefore unlikely to be responsible for either of these deafnesses. During the characterization of TUBA2, the gene encoding connexin 26 was proven to be responsible for both DFNB1 and DFNA3 (D. P. Kelsell et al., 1997, Nature 387: 80-83). However, the present data offer the possibility of testing the involvement of the TUBA2 gene in the Clouston hidrotic ectodermal dysplasia and the Kabuki syndrome, two genetic diseases that have recently been mapped to the 13q11 region.