HLA Genotyping Group

The Department of HLA has been performing HLA genotyping as the first laboratory in the Czech Republic. These tests were introduced to routine practice in 1993 for patients of the IHBT, Department of Pediatric Hematology and Oncology, 2nd Faculty of Medicine, Charles University in Prague and Motol University Hospital, as well as other clinical users.

The HLA system (Human Leukocyte Antigens System) is the main human histocompatibility complex. The system is genetically located on the short arm of chromosome six (6p21.31 - 6p21.33). This large complex of genes is extremely polymorphic. Its products are transmembrane proteins, which determine the surface molecules (antigens) located on the plasma membrane of cells. The HLA system is primarily responsible for distinguishing self from non-self structures, and thus they initiate the cascade of immune reactions.

A precise determination of HLA genotype in a patient and his/her donor is one of the basic conditions of successful allogeneic hematopoietic stem cell transplantation (allo-HSCT). Mismatch in HLA system between a patient and a donor can cause the graft versus host disease (GvHD), which is a serious or even fatal complication of allo-HSCT.

Routinely we perform genotyping of the most important transplant loci of HLA class I and II: HLA-A, -B, -C, -DRB1 and -DQB1 in patient indicated for allogeneic stem cell transplantation, their related donors and selected unrelated donors from the Czech and foreign stem cell donor registries.

Specific alleles of HLA are known to be associated with some diseases (for instance: rheumatoid arthritits, coeliac disease, narcolepsy, etc.) This leads to a higher relative risk of the disease in individuals carrying these alleles.

The laboratory determines HLA markers associated with diseases:

• Presence of HLA-B*27 for the association with rheumatoid arthritis
• Presence of HLA-DQB1*06:02 for the association with narcolepsy
• Presence of predisposing alleles of HLA-DQA1 and DQB1 associated with coeliac disease based on European Society for Pediatric Gastroenterology, Hepatology, and Nutrition Guidelines for the Diagnosis of Coeliac Disease

The department of HLA organizes External Proficiency Testing programs for these HLA markers.

In agreement with clinicians we are able to perform the genotyping of selected HLA loci as additional information for the determination of other diseases associated with HLA.

HLA determination is an important tool of pharmacogenetics. Selective HLA markers can predict responsiveness, non-responsiveness or sensitivity of a patient to specific drugs. The laboratory performs routine HLA-B*57:01 screening in Czech HIV positive patients prior to drug administration to prevent hyper-sensitive reaction.

A number of genotyping methods are used in the laboratory:

• Polymerase-chain reaction with sequence-specific primers
• Sequence-Based Typing

Results are evaluated by using special software connected to the international IMGT/HLA database and regularly updated. This ensures maximum accuracy of released results.