DMWD contains 2 regions with significant homology to WD repeats. Northern blot analysis detected highest expression in mouse brain and testis, with significant expression in heart and lung. In situ hybridization of mouse embryos detected ubiquitous low expression in all tissues and enhanced expression in adult brain and testis. Dmwd expression began before embryonic day 9.5. From day 14.5 onward, Dmwd mRNA was detected in all neural tissues, especially in the telencephalon and mesencephalon. Later, expression was evident in distinct tubules of the mature testis and was restricted to secondary spermatocytes of stages VIII to XII of the spermatogenic proliferation cycle.Northern blot analysis of human and baboon RNA detected a 3-kb transcript.