HLA Genetics & Molecular Biology Flashcards

What is the primary function of beta-2 microglobulin (β2m) in HLA class I molecules?

Answer: Stabilizes the alpha chain and is required for surface expression

β2m is a non-covalently associated light chain that stabilizes the HLA class I alpha chain and is essential for proper folding and surface expression.

Which type of HLA typing method directly determines the nucleotide sequence of HLA alleles?

Answer: Sequence-Based Typing (SBT/SBT-NGS)

SBT (Sanger sequencing) and NGS-based methods directly read the nucleotide sequence to assign high-resolution HLA alleles.

An HLA allele designated HLA-A*02:01 indicates what level of resolution?

Answer: Second-field (allele-level) resolution

The two-field nomenclature (e.g., 02:01) specifies the allele group (02) and the specific allele within that group (01), representing allele-level resolution.

Which HLA gene is encoded outside the classical MHC class I region yet is important in NK cell regulation?

Answer: HLA-E

HLA-E is a non-classical class I molecule encoded within the MHC that presents leader-sequence peptides and serves as a primary ligand for NK cell NKG2 receptors.

What does 'cis' configuration refer to in the context of HLA DQ heterodimers?

Answer: Alpha and beta chains encoded on the same chromosome

A cis DQ heterodimer is formed by DQA1 and DQB1 chains encoded on the same parental haplotype/chromosome.

Which molecular typing technique uses allele-specific primers to amplify target HLA sequences?

Answer: SSP (Sequence-Specific Primers)

SSP uses primers designed to amplify only specific alleles or allele groups under defined PCR conditions, providing rapid low-to-intermediate resolution typing.