The gene tprd, which contains three tetratricopeptide domains, has been recently localized in the Down syndrome (DS) chromosomal region 1. We have cloned a cDNA encoding part of the murine ortholog of tprd and used it to characterize the expression pattern of this gene during development and at the adult stage. At E8.5 the expression is uniform. In the later stages of embryogenesis, although expression remains ubiquitous, a pattern of tissues with particularly high expression develops: the strong expression is restricted to non proliferating zones of the nervous system such as the external layer of the cortex, the spinal cord, the cranial and root ganglia and the nerves. In the brain of adult mouse the strongest signals are observed in layers II-III and V-VI of the cortex, in the hippocampus and in the cerebellum, which correspond to the abnormal brain regions seen in DS patients.