ABSTRACT
The assignment of null alleles is clinically relevant in stem cell transplantation, in particular for donor selection. It is unclear how questionable (Q) alleles, having an unknown expression profile, should be considered in matching criteria. In this study we analyzed the RNA and protein expression profile of a questionable allele encountered in a sample of the Guadeloupe population: GD23Q, HLA-A(∗)23:19Q, 29:02:01. Full-length DNA sequencing of HLA-A(∗)23:19Q revealed a single polymorphism at position 619 (G>A) compared to HLA-A(∗)23:01:01. Serological typing showed only the presence of HLA-A29; HLA-A(∗)23:19Q was not detected on the cell surface. The absence of HLA-A(∗)23:19Q surface expression was shown by flow cytometry using a directly labeled monoclonal antibody and a panel of five indirectly labeled polyclonal antibodies all directed against HLA-A23 (HLA-A9) molecules. Allele specific amplification revealed the absence of intact full-length mRNA, but the presence of two major alternatively spliced mRNAs: sequencing identified that in one variant exon 3 is missing and in the other variant introns 2 and 3 are retained. Based upon the lack of HLA-A(∗)23:19Q surface expression and the presence of aberrant mRNA transcripts only, this study shows that HLA-A(∗)23:19Q is non-expressed.
Subject(s)
Donor Selection , HLA-A Antigens/biosynthesis , HLA-A Antigens/genetics , Histocompatibility Testing/methods , Stem Cell Transplantation , Alleles , Alternative Splicing , Guadeloupe , Humans , Polymorphism, Single Nucleotide , RNA, Messenger/genetics , Reference Standards , Reproducibility of Results , Sequence Analysis, RNAABSTRACT
The new HLA-B*15:220 allele shows a single-nucleotide substitution in exon 1 at position 47 (C>T) when compared to its closest allele HLA-B*15:03:01, resulting in an amino acid substitution from Ala to Val in the signal peptide at codon -9.
Subject(s)
Alleles , Amino Acid Substitution , Exons/genetics , HLA-B Antigens/genetics , Mutation, Missense , Guadeloupe , HumansABSTRACT
The new HLA-A*23:38N allele shows a single-base deletion in exon 2, resulting in a frame shift and a premature stop codon.
Subject(s)
Alleles , Codon, Terminator/genetics , Exons/genetics , Frameshift Mutation , Guadeloupe , HLA-A Antigens , HumansABSTRACT
Infectious complications are a leading cause of morbidity and mortality in patients with sickle cell disease. Several mechanisms are supposed to contribute to this susceptibility. The exact reasons for the susceptibility of sickle cell patients to infection are not clear and are still a matter of debate. Interferon gamma (IFNgamma) is a key cytokine involved mainly in the defence against intracellular pathogens. We investigated a possible association of an IFNgamma +874 T/A polymorphism and infectious complications in sickle cell patients. Seventy-two sickle cell patients were typed for +874 T/A IFNgamma polymorphism. Genotype frequencies were different between cases and controls. Indeed, the T allele frequency was significantly higher in patients with infections than in patients without infections (P = 0.014). Our results suggest that the +874 T/A IFNgamma polymorphism is associated with infectious complications in sickle cell patients. T allele could be involved in infections in sickle cell patients.
