KILLER IMMUNOGLOBULIN LIKE RECEPTOR 2DL4 ALLELE DIVERSITY IDENTIFIED BY PCR

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TITLE: KILLER IMMUNOGLOBULIN LIKE RECEPTOR 2DL4 ALLELE DIVERSITY IDENTIFIED BY PCR–SSOP

Fionnuala Williams, Carole Sleator, Martin D. Curran, Derek Middleton.

Histocompatibility & Immunogenetics Laboratory, Belfast, Northern Ireland, United Kingdom

The killer immunoglobulin–like receptor (KIR) genes have emerged as a highly polymorphic multigene family. In addition to the variable gene content observed within the population significant allelic diversity within the known KIR genes is now emerging.

A method identifying KIR 2DL4 allele variation based on PCR–SSOP has been developed. Fourteen nucleotide sequence submissions, were retrieved from the GenBank databank (www.ncbi.nlm.nih.gov), which when aligned accounted for ten putative 2DL4 allele variants. PCR products (approximately 1440 base pairs) containing exons 3 and 4 of the KIR 2DL4 gene were specifically generated with primers flanking this region. Fifteen digoxigenin labelled probes were designed to provide distinct discrimination of the 2DL4 variant alleles.

When this method was applied to a Northern Irish healthy control group (n = 162), only five of the ten putative alleles were identified, creating fifteen different genotypes within the population. One unusual probe pattern was identified in two individuals, suggesting the presence of a novel 2DL4 allele within this group. Further characterisation of this allele is in progress. The most common allele, corresponding to acc. no. af034773, was found at 32.7%, while the least common (acc. no. af285436) was found at 3.7%. The various genotypes observed were found to be in Hardy–Weinberg equilibrium. The same five alleles were again observed as the only 2DL4 alleles present within twelve CEPH families (n = 48), obtained from the NK component of the 13th IHW, and forty Northern Irish families (n = 220). The five alleles segregated as expected within all family units. Therefore it seems likely that the other five allele sequences not detected in this study represent rare alleles or sequence artefacts.