The human “interferon- β2/hepatocyte stimulating factor/interleukin-6” gene: DNA polymorphism studies and localization to chromosome 7p21

Abstract

The human interferon- β 2 gene (IFNB2) product is identical to that for the B-cell stimulation factor-2 (BSF-2), the hybridoma growth factor (HGF) (“interleukin-6”), and the hepatocyte stimulating factor (HSF). Proteins derived from this gene mediate the plasma protein response to tissue injury (acute-phase response) and regulate the growth and differentiation of both B and T cells. By using the enzymes MspI, BstNI, and BglI, three polymorphic systems were detected with probes for the IFNB2 gene. The MspI and BglI polymorphisms are likely to be due to base pair substitutions; the BstNI polymorphism was revealed by nine other enzymes and is likely to be due to DNA insertions within 1 kb of the 3′ flanking region of the gene. This region is rich in AT dinucleotides, and slippage at DNA replication may generate the insertions of between 0.07 and 0.23 kb that were observed. The polymorphic MspI site also lies within the vicinity of the fifth exon. The BglI polymorphic site is likely to lie in 5′ flanking DNA. The three polymorphisms are separate, and a variety of haplotypes was observed. A low level of linkage disequilibrium exists between the MspI and the BglI alleles. MspI and BstNI polymorphisms were observed in Caucasoids, CAR Pygmies, Zaire Pygmies, Melanesians, and Chinese but at differing frequencies, and not all alleles were present in all populations. The BglI polymorphism was observed in Caucasoids and Africans only. Linkage studies involving the IFNB2 gene and 27 other chromosome 7 markers have localized it to between D7S135 and D7S370 at 7q22–p21. In situ hybridization has assigned this gene to 7p21–p15; combining data from linkage and in situ hybridization experiments places IFNB2 at 7p21.