Complete sequence analysis of the A*1103 allele

Area of Science:

• Immunogenetics
• Molecular Biology
• Human Leukocyte Antigen (HLA) research

Background:

• The human leukocyte antigen (HLA) system plays a crucial role in immune response and transplantation.
• Allelic variation within HLA genes, particularly the HLA-A locus, contributes to diverse immune profiles.

Purpose of the Study:

• To report the full-length sequence of a newly identified HLA-A*11 variant.
• To characterize the genetic and amino acid differences of this novel variant compared to known alleles.

Main Methods:

• Amplification Refractory Mutation System-Polymerase Chain Reaction (ARMS-PCR) for initial identification.
• Serological testing to support variant discovery.
• Cloning and DNA sequencing for full-length sequence confirmation.

Main Results:

• A novel HLA-A*11 variant, designated A*1103, was identified in a family of oriental origin.
• A*1103 shares sequence similarity with A*1101 in exon 2 but presents distinct differences in exon 3 at codons 151 and 152.
• These polymorphisms result in two amino acid substitutions: a conserved His->Arg at position 151 and an Ala->Glu substitution introducing a negative charge at position 152, both located in the alpha2 helical region.
• The amino acid motif at codons 151-152 is unique to A*1103 among HLA-A alleles but is common in HLA-C locus alleles.

Conclusions:

• The discovery of HLA-A*1103 expands the known allelic repertoire of the HLA-A locus.
• The specific amino acid substitutions in A*1103 may influence its interaction with T-cell receptors or peptide binding, warranting further functional investigation.
• This finding contributes to a deeper understanding of HLA polymorphism and its implications in population genetics and immunology.