[Mice SI/Col: a study model in the research of genes involved in situs inversus]

The SI/Col mouse is carrier of the i.v. mutation which expresses itself in an autosomal recessive mode. Fifty per cent of mice born of homozygotic i.v./i.v. parents are normal and 50% present an abnormality of lateralisation of the thoracic and abdominal organs with cardiac malformations involving the venous, atrial, ventricular and arterial segments. Identifying the i.v. mutation may improve our understanding of the genesis of the heterotaxic syndrome in man. With the help of return crossing with wild mice, the authors studied segregation of 10 makers of the murine, chromosome 12 of the situs inversus mice. The genetic map constructed from this data places the i.v. mutation near the telomeric extremity of the murine chromosome 12. Given the inter-species conservation between this region and the telomeric region of the human chromosome 14, it is a candidate region for the search of a homologous human gene in syndromes of heterotaxis.