Aim: Previous work (Kotsch and Blasczyk, 2000) has shown that a DRB1*13:13 haplotype does not have an associated DRB3 gene and lacks the DRB2 pseudogene suggesting a regional structure like that of the DR8 haplotype. For HLA typing purposes we wished to extend the known sequence for this allele.
Method: Using probe-based hybrid capture and subsequent sequencing of genomic fragments from cell line TER269 (XX406) a DNA sequence for DRB1*13:13 was assembled using TypeStream VisualTM (TSV) software.
Results: The DRB1*13:13 allele sequence has been extended to include exon 1 and the surrounding region. This sequence is similar to other DRB1*13 alleles. A contiguous sequence from the end of intron 1 to the beginning of the 3’UTR shows that the sequence up to codon 70 of exon 2 is identical to that of DRB1*13:03:01:01. From codon 71 of exon 2 to the end of the sequence (approximately nucleotide 97 of the 3’UTR) is identical to that of DRB1*08:03:02:02
Conclusion: The DR8 haplotype has been hypothesized to result from a genetic contraction (our estimated deletion of 63.7 kb) between DRB1*12 and DRB3 (Svensson et al., 1996). The exact mechanism to generate DRB1*13:13 remains open whether by gene conversion using the DR8 haplotype as template or by independent regional contraction between DRB1*13 and DRB3. However, the existence of this allele sequence raises the possibility that other alleles associated with the DR52 supergroup may also lack a DRB3 gene. This will have implications regarding exact HLA typing and matching.
