What are HLA DQ2 and DQ8


The HLA-DQ molecule is a protein structure that occurs on the cell surface of various cells of the immune system (so-called "antigen-presenting cells" - these can be monocytes, macrophages, B-lymphocytes and many more). In principle, these are components of the immune system to differentiate between the body's own and foreign structures.

The basis of all endogenous protein structures is the so-called “genetic code” - also called “genetic material” or “DNA” (deoxyribonucleic acid). The genetic material is located in the nucleus of all body cells, and its exact composition is unique for each person - comparable to the fingerprint, which is also unique for each person.

The specialty of the HLA-DQ molecule is that there are considerable differences between people in terms of the fine molecular structure of this protein. Two forms of the HLA-DQ molecule are of particular interest for medicine:

Because in patients who suffer from celiac disease (so-called "gluten intolerance"), HLA-DQ molecules of type 2 and / or 8 are found in more than 99 percent of cases.

A so-called HLA-DQ2 & 8 genotyping can be carried out to examine the fine structure of the HLA-DQ molecule. This examination is a special laboratory medical procedure for the genetic analysis of the genetic material on which the HLA-DQ molecule is based.

All that is required for this genetic test is a simple blood draw. In the medical laboratory, the genetic material is extracted from the blood and multiplied (read: "amplified") using the laboratory process of the polymerase chain reaction (PCR - "Polymerase Chain Reaction"). Since several DNA regions are amplified at the same time during the multiplication of the genetic material in the course of this investigation, one speaks of a so-called "multiplex PCR".

In addition to the multiplex PCR method, there is also the option of deciphering the exact sequence of the patient's genetic code. This testing procedure is called "DNA sequencing". Since this laboratory method is more complex than the multiplex PCR, DNA sequencing for HLA-DQ2 & 8 genotyping is only carried out in the context of special diagnostic questions.