The human complement C8G gene, a member of the lipocalin gene family: polymorphisms and mapping to chromosome 9q34.3

Abstract

Summary Complement component C8 is a plasma glycoprotein consisting of three nonidentical polypeptide chains (α, β, γ) which are encoded by three separate genes (C8A, C8B, C8G). The γ chain whose functional role remains undefined is not related to any other complement protein but is a member of the lipocalins, a family of proteins that bind small hydrophobic ligands. The present report describes the first known polymorphisms for the human C8G gene, namely one polymorphic site in exon 1 (207T/G) and two polymorphic sites in intron 1 (213 + 37G → A; 213 + 65del3). Specific typing can be performed using simple polymerase chain reaction‐based assays. C8G genotyping in eight CEPH reference families demonstrated that C8G is closely linked to a series of marker loci located in the most telomeric region of chromosome 9q. Multipoint analysis placed C8G with 1000:1 support distal to D9S207. C8G is thus located at 9q34.3. Remarkably, this chromosomal region contains at least four other lipocalin genes.