Null, questionable and abberantly expressed Alleles
Here are listed all the HLA alleles that have been shown to be either not expressed (Null alleles that have the suffix 'N'), or the alleles that have been shown to be alternatively expressed have the suffix 'L', 'S', 'C', 'A' or 'Q'.
The suffix 'L' is used to indicate an allele that has been shown to have 'Low' cell surface expression when compared to normal levels. The 'S' suffix is used to denote an allele specifying a protein which is expressed as a soluble, 'Secreted' molecule, but is not present on the cell surface. A 'C' suffix is used to indicate an allele product which is present in the 'Cytoplasm', but not on the cell surface. An 'A' suffix is used to indicate an 'Aberrant' expression, specifically where there is some doubt as to whether a protein is expressed at all. A 'Q' suffix is used when the expression of an allele is 'Questionable' given that the mutation seen in the allele has previously been seen in other aleles and shown to affect normal expression levels.
As of April 2025, there are no alleles which have been named with the 'C' or 'A' suffix.
All numbering and descriptions are based on an alignment to the exon sequence of the standard reference allele for that locus e.g. A*01:01:01:01 for null HLA-A alleles. A full explanation of how the mutations are described is provided after the table.