Isolation of a novel gene from the DiGeorge syndrome critical region with homology to Drosophila gdl and to human LAMC1 genes.

DiGeorge syndrome, and more widely the CATCH 22 syndrome, are associated with microdeletions in chromosomal region 22q11.2. A critical region of 500 kb has been delimited within which maps the breakpoint of a balanced translocation associated with mild CATCH 22 phenotypes. We report the isolation from this critical region of a novel gene, DGCR6, which maps 115 kb centromeric to the balanced translocation breakpoint. The DGCR6 gene product shares homology with the Drosophila melanogaster gonadal protein, which participates in gonadal and germ-line cells development, and with the human laminin. gamma-1 chain, which upon polymerization with alpha- and beta- chains forms the laminin molecule. Laminin binds to cells through interaction with a receptor and has functions in cell attachment, migration and tissue organization during development. DGCR6 could be a candidate for involvement in the DiGeorge syndrome pathology by playing a role in neural crest cell migration into the third and fourth pharyngeal pouches, the structures from which derive the organs affected in DiGeorge syndrome.