EFFECT OF INCREASED GENE DOSAGE EXPRESSION ON THE ALPHA-INTERFERON RECEPTORS IN DOWNS-SYNDROME

The gene coding for the alpha,beta-interferon (alpha,beta-IFN) recepto r is localized to chromosome 21. Cells from patients with Down's syndr ome contain an extra chromosome 21, and thereby an expected 1.5-times increase in the number of genes located to this chromosome and in cons equence a 1.5-times increase in cell surface alpha-IFN receptors. Actu al measurements of these by competition binding experiments with human recombinant alpha-IFN on peripheral blood mononuclear cells (PBMC) fr om patients with Down's syndrome resulted in a mean of 1.69, which is in accordance to the theoretical 1.50, but slightly overestimated due to the calculation method. The increased gene dosage of the alpha-IFN receptor was quantitatively verified by Southern blot-hybridizations. Further characterization of alpha-IFN receptor binding showed insignif icant differences in dissociation constants among patients and healthy individuals.