Gene structure and chromosomal localization of mouse Opa1 : its exclusion from the Bst locus

Autosomal dominant optic atrophy type 1 (DOA) is the most common form of hereditary optic atrophy in human. We have previously identified the OPA1 gene and shown that it was mutated in patients with DOA. OPA1 is a novel member of the dynamin GTPase family that play a role in the distribution of the mitochondrial network. The Bst (belly spot and tail) mutant mice show atrophy of the optic nerves and previous mapping data raise the possibility that Bst and OPA1 are orthologs. In order to analyse the Bst mouse as a model for DOA, we therefore characterized mouse Opa1 and evaluated it as a candidate for the Bst mutant mouse.

Comparison of mouse and human OPA1 sequences revealed 88% and 97% identity at the nucleotide and amino acid levels, respectively. Presence of alternatively spliced mRNAs as seen in human was conserved in the mouse. Screening of the whole mRNA coding sequence and of the 31 exons of Opa1 did not reveal any mutation in Bst. Using a radiation hybrid panel (T31), we mapped Opa1 to chromosome 16 between genetic markers D16Mit3 and D16Mit124, which is 10 cM centromeric to the Bst locus.

On the basis of these results we conclude that Opa1 and Bst are distinct genes and that the Bst mouse is not the mouse model for DOA.