HLA (Human Leukocyte Antigen)
Definition
Cell-surface glycoproteins encoded by the major histocompatibility complex (MHC) on chromosome 6p21. They present peptide antigens to T cells and are the primary targets of graft rejection responses. Their extreme polymorphism underpins their use as genetic markers in relationship testing.
- Location
- MHC, chromosome 6p21
- Molecule type
- Cell-surface glycoproteins
- Primary function
- Present peptide antigens to T cells
- Forensic relevance
- Extreme polymorphism used in relationship testing
Common questions
Why was HLA typing largely replaced by STR profiling for routine forensic identification?+
STR loci are more numerous, easier to type from small or degraded samples, and simpler to interpret statistically, so HLA typing today is mainly reserved for supplementary relationship testing or transplant compatibility work.
What makes HLA useful specifically for relationship testing rather than individual identification?+
HLA alleles are inherited as linked haplotype blocks from each parent, which makes parent-child and sibling relationships easier to trace through shared haplotypes than through independently assorting markers.
Related terms
- Complement-Dependent Cytotoxicity (CDC)
- A serological HLA typing method in which test lymphocytes are incubated with HLA-specific antibody and then with complement. If the antibody binds,...
- HLA Haplotype
- The specific combination of HLA alleles inherited as a block on one copy of chromosome 6. Because HLA loci are tightly linked,...
- Linkage Disequilibrium
- The non-random association of alleles at different loci within a population. Certain HLA allele combinations (e.g., HLA-A1 with HLA-B8 with HLA-DR3) occur...
- Paternity Index (PI)
- A likelihood ratio that compares the probability of the observed serological profile if the alleged father is the biological father to the...
- Sequence-Specific Primer PCR (SSP)
- A molecular HLA typing method that uses primer pairs designed to amplify only if a specific allele sequence is present. Results are...