Duplication in the HLA‐B/‐C region on the short arm of chromosome 6

Background and Objectives Many family investigations of the HLA region are performed in order to identify HLA identical related stem cell donors. In rare cases, deviations from the expected inheritance can be observed. Such a case is shown in this presentation. Materials and Methods Alleles of the HLA complex have been defined in the members of an Austrian family with atypical segregation of HLA alleles by using the following methods: HLA DNA typing by low‐, medium‐ and high‐resolution techniques; genotyping of short tandem repeat (STR) markers in the HLA region; and array‐based genome‐wide single‐nucleotide polymorphism (SNP) analyses. Results A duplication of the HLA region encompassing HLA‐B, HLA‐C and the STR loci D6S2678 and STR‐MICA is detected. Conclusion A duplication in the HLA‐B/‐C region of the HLA system is observed, which results from an unequal crossing‐over encompassing a chromosomal region of around 377 kb.