The DQA1*0104 allele is carried by DRB1*1001- and DRB1*1401-positive haplotypes in Caucasians, Africans and Orientals.
The DQA1*0104 allele is known to differ from DQA1*0101 by a single nucleotide in the sequenced part of the first exon. DQA1*0104 has a guanine in the second position of the second expressed codon, whereas DQA1*0101 and all other sequenced DQA1 alleles have an adenine in that position, changing aspartic acid to glycine. The DQA1*0104 allele was originally described in African Americans with the DRB1*12, DRB3*0101, DQA1*0104, DQB1*0501, DRB1*12, DRB3*0202, DQA1*0104, DQB1*0605 or DRB1*14, DQA1*0104, DQB1*0503 haplotypes. When developing DQA1 typing by PCR amplification with sequence-specific primers (PCR-SSP), we observed that all DR10- and DR14-positive samples carried the DQA1*0104 allele, whereas all DRB1*01-positive DNAs carried the closely related DQA1*0101 allele. In the present study, samples representing the major ethnic groups with DR-DQ haplotypes known to carry the DQA1*0104 allele or the very similar DQA1*0101 allele were investigated by TaqI RFLP analysis, PCR-SSP typing and nucleotide sequencing. The DQA1*0104 allele was found to differ from DQA1*0101 not only in the second expressed codon, but also by a productive mutation in the signal peptide. All investigated DRB1*1001-(n = 24) and DRB1*1401-positive (n = 25) haplotypes, defined by homozygosity or association, of Caucasian, African or Oriental origin carried the DQA1*0104 allele, whereas the DQA1*0101 allele was found on all DRB1*01-positive (n = 32) haplotypes. These findings demonstrate that in the assignment of HLA class II alleles, polymorphism outside the second exon sometimes must be considered.(ABSTRACT TRUNCATED AT 250 WORDS)
Fogdell
A
A
Center for BioTechnology, Karolinska Institute, NOVUM, Huddinge, Sweden.
Olerup
O
O
D000483:Alleles; D000595:Amino Acid Sequence; D044466:Asian People / Q000235:genetics*; D001483:Base Sequence; D044383:Black People / Q000235:genetics*; D017931:DNA Primers; D005091:Exons / Q000235:genetics; D005802:Genes, MHC Class II; D006683:HLA-DQ Antigens / Q000235:genetics*; D059848:HLA-DQ alpha-Chains; D059866:HLA-DQ beta-Chains; D006684:HLA-DR Antigens / Q000235:genetics*; D059811:HLA-DRB1 Chains; D006239:Haplotypes / Q000235:genetics*; D006801:Humans; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D011110:Polymorphism, Genetic; D044465:White People / Q000235:genetics*; D001741:Black or African American
D017931:DNA Primers; D006683:HLA-DQ Antigens; D059848:HLA-DQ alpha-Chains; D059866:HLA-DQ beta-Chains; C069050:HLA-DQA1 antigen; C069051:HLA-DQB1 antigen; D006684:HLA-DR Antigens; D059811:HLA-DRB1 Chains