A Position Effect on TRPS1 Is Associated with Ambras Syndrome in Humans and the Koala Phenotype in Mice

The study identified a position effect on the TRPS1 gene as a probable cause of Ambras syndrome (AS) in humans and the Koala (Koa) phenotype in mice, both characterized by hypertrichosis. Researchers defined an 11.5 Mb candidate interval on chromosome 8q linked to AS and found that TRPS1 was either deleted or significantly downregulated in patients with chromosomal rearrangements. In Koa mice, a similar downregulation of Trps1 was observed due to an inversion creating new Sp1 binding sites. These findings suggest that the position effect on TRPS1 expression leads to the excessive hair growth seen in both AS and the Koa phenotype.