To determine the effect of DYRK1A overexpression on BDNF in the genomic context of both complete trisomy 21 and partial trisomy 21, we used lymphoblastoid cell lines from patients with complete aneuploidy of human chromosome 21 (three copies of DYRK1A) and from patients with partial aneuploidy having either two or three copies of DYRK1A.
These alterations are comparable with those found in the partial trisomy chromosome 16 murine models of DS and suggest a causative role of DYRK1A in mental retardation and in motor anomalies of DS.
We have used DS fetal brain samples in search for initial evidence and employed engineered mice with MMU16 partial trisomy (Ts65Dn) or direct excess of the splicing-associated nuclear kinase Dyrk1A, overdosed in DS for further analyses.
In this region, we focused on a 1.6-Mb region between a NotI site, LA68 (D21S396, which is mapped distal to D21S17) and ERG, because analysis of a Japanese DS family with partial trisomy 21 revealed that the proximal border of its triplicated region was distal to LA68.
Molecular genetic analysis of Down syndrome (DS) patients with partial trisomy 21 allowed us to reinforce the supposition that ETS2 may be a gene of the minimal DS genetic region.
The human genome database was searched for candidate genes and we propose the following nine genes located in the 6p22→6pter region for their potential contribution to the phenotype of partial trisomy 6p22→pter and persistent hyperplastic primary vitreous (PHPV) with retinal detachment: Forkhead box Q1 (FOXQ1), FOXF2, FOXC1, NRN1, EDN1, ATXN1, DEK oncogene, E2F3, and NRNS1.
The human genome database was searched for candidate genes and we propose the following nine genes located in the 6p22→6pter region for their potential contribution to the phenotype of partial trisomy 6p22→pter and persistent hyperplastic primary vitreous (PHPV) with retinal detachment: Forkhead box Q1 (FOXQ1), FOXF2, FOXC1, NRN1, EDN1, ATXN1, DEK oncogene, E2F3, and NRNS1.
Thus, loss of Gata1 and partial trisomy of chromosome 21 orthologs, when combined, do not appear to be sufficient to induce TMD or AMKL-like phenotypes in mice.