title: Diversity associated with the second expressed HLA-DRB locus in the human population.
abstract: Although diversity within the HLA-DRB region is predominantly focused in the DRB1 gene, the second expressed DRB loci, DRB3, DRB4, and DRB5, also exhibit variation. Within DRB1(*)15 or DRB1(*)16 haplotypes, four new variants were identified: 1) two new DRB5 alleles, DRB5*0104 and DRB5*0204, 2) a haplotype carrying a DRB1(*)15 or *16 allele without the usual accompanying DRB5 allele, and 3) a haplotype carrying a DRB5(*)0101 allele without a DRB1(*)15 or *16 allele. The evolutionary origins of these haplotypes were postulated based on their associations with the DRB6 pseudogene. Within HLA haplotypes which carry DRB3, a new DRB3(*)0205 allele and one unusual DRB3 association were identified. Finally, two new null DRB4 alleles are described: DRB4(*)0201N, which exhibits a deletion in the second exon, and a second allele, DRB4(*)null, which lacks the second exon completely. Gene conversion-like events and variation in the number of functional genes through reciprocal recombination and inactivation contribute to the diversity observed in the second expressed HLA-DRB loci.
authors.affiliation: Naval Medical Research Institute, Bethesda MD 20889, USA.
authors.forename: F
authors.initials: F
authors.lastname: Robbins
authors.forename: C K
authors.initials: CK
authors.lastname: Hurley
authors.forename: T
authors.initials: T
authors.lastname: Tang
authors.forename: H
authors.initials: H
authors.lastname: Yao
authors.forename: Y S
authors.initials: YS
authors.lastname: Lin
authors.forename: J
authors.initials: J
authors.lastname: Wade
authors.forename: N
authors.initials: N
authors.lastname: Goeken
authors.forename: R J
authors.initials: RJ
authors.lastname: Hartzman
mesh_terms: D000483:Alleles; D001483:Base Sequence; D014644:Genetic Variation; D006684:HLA-DR Antigens / Q000235:genetics*; D006801:Humans; D008969:Molecular Sequence Data
chemical_list: D006684:HLA-DR Antigens