A physical map of the C6 and C7 complement component gene region on chromosome 5p13

Three of the seven genes for terminal complement components, C6, C7 and C9, are located in a tight linkage group on chromosome 5p13. These three proteins and two of the polypeptide chains of C8 show strong structural similarities, but the C8 genes are on chromosome 1. Deficiencies of each of the gene products are not uncommon, and there is a combined incomplete deficiency of C6 and C7 in which we have a particular interest. It is in this connection that we have sought to map the region, as the gross arrangement of the genes will be important information in our understanding of the cause of the combined deficiency. We have used some of the information on the intron/exon structure of C6 to devise PCR methods for screening YAC pools and have applied this to a human YAC library. We have identified two YACs containing the C6 and C7 genes, and we have mapped them.