Here we investigated the molecular mechanisms underlying impaired neuronal proliferation in DS and, more specifically, a regulatory role for dual-specificity tyrosine-(Y) phosphorylation-regulated kinase 1A (Dyrk1A), a DSCR gene product, in embryonic neuronal cell proliferation.
The Down syndrome chromosome region-1 (DCR1) on subband q22.2 of chromosome 21 is thought to contain genes contributing to many features of the trisomy 21 phenotype, including dysmorphic features, hypotonia, and psychomotor delay.
The deletion does not involve the "Down syndrome chromosome" region, the region of chromosome 21 which in trisomy causes most of the manifestations of Down syndrome.
Thus, the complex phenotype that constitutes Down syndrome may in large part simply result from the overdosage of only one or a few genes within the DCR and/or region D21S55-MX1.
The triplication of a region of chromosome 21 around D21S55 in 21q22.2-22.3 has been involved in the main features of Down syndrome including mental retardation (Down syndrome chromosome region: DCR).