HLA Haplotype
Definition
The specific combination of HLA alleles inherited as a block on one copy of chromosome 6. Because HLA loci are tightly linked, alleles at HLA-A, -B, -C, -DR, and -DQ tend to segregate together as a unit. Each parent passes one complete haplotype to each child.
- Location
- Chromosome 6, MHC region
- Loci included
- HLA-A, -B, -C, -DR, -DQ
- Inheritance
- One complete haplotype per parent per child
- Basis
- Tight genetic linkage across loci
Common questions
How does haplotype inheritance help in relationship testing?+
Because a full haplotype passes to a child largely intact, a child should carry one haplotype matching each biological parent, and comparing observed haplotypes against alleged parents can support or contradict a claimed relationship.
Can recombination break a haplotype apart between generations?+
Yes, though rarely, because recombination hotspots exist within the MHC region. Rare recombinant haplotypes are a known source of apparent mismatches in HLA-based testing and must be interpreted carefully.
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 (Human Leukocyte Antigen)
- Cell-surface glycoproteins encoded by the major histocompatibility complex (MHC) on chromosome 6p21. They present peptide antigens to T cells and are the...
- 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...