A30-Cw5-B18-DR3-DQ2 (HLA Haplotype)
HLA A30-Cw5-B18-DR3-DQ2 (A30::DQ2) is a multigene haplotype that extends across a majority of the major histocompatibility complex on human chromosome 6. A multigene haplotype is a set of inherited alleles covering several genes, or gene-alleles. Long haplotypes, like A30::DQ2, are generally the result of descent by common ancestry. As haplotypes increase in size, Chromosomal recombination fragments them in a generation dependent process.A30::DQ2 can be written in an extended form covering the major histocompatibility loci as follows: HLA A*3002 : Cw*0501 : B*1801 : DRB1*0301 : DQA1*0501 : DQB1*0201. There are several composite haplotypes, A30-Cw5-B18 and a variant A30-CBL-B18 comprise A30::B18, there is also the B18-DR3 component and the HLA DR3-DQ2.5. Other haplotypes such as Cw5-B16-DR3 or B8-DR3-DQ2.5 have been presented in the literature.A dozen inflammatory diseases of the immune system can attribute some risk to the haplotype. Some disease like coeliac disease primarily associate with certain genes. While other diseases, like type 1 diabetes may have several, highly different, genes that attribute risk. Still other diseases, like myasthenia gravis have undetermined linkage to the haplotype.Haplotypes of A30-B18 or Cw5-B18 have been studied (see allelefrequencies.net and IHWC 1991). Despite that large areas of Northern Africa have not been studies by HLA, A30::DQ2 appears to have originate southwest of is current mode in Sardinia. Gómez-Casado et al. (2000) observed that the haplotype is of likely paleo North African origin, and later studies of North Africa support that finding. Northern Iberians share with Sardinians a high frequency of the haplotype. However, there are some differences, linkage disequilibrium in Sardinians is highest whereas the Basque haplotype frequently has a different Cw allele indicating different origin for the haplotype.