HLA Typing: 

Human leukocyte antigen (HLA) typing is a method to determine how closely a transplant recipient's tissues match their potential donor's tissues. Human leukocyte antigen (HLA) typing is used to match patients and donors for bone marrow or cord blood transplants. 

HLA are proteins, or markers, found on most cells in your body. HLA typing is a medical test used to assess whether organ and blood marrow donors are suitably and safely matched to a transplant recipient.

HLA testing matches organ and tissue transplant recipients with compatible donors. Different kinds of transplants require different levels of matching between donors and recipients.

Human leukocyte antigen (HLA) typing is a method to determine how closely a transplant recipient's tissues match their potential donor's tissues.

HLA typing is a medical test used to assess whether organ and blood marrow donors are suitably and safely matched to a transplant recipient.

What is an HLA match?

Human leukocyte antigens are proteins you inherit from your parents. Your HLA proteins, or markers, make up your HLA type. Your immune system uses HLA markers to recognize which cells belong in your body and which do not. 

An HLA match is the number of HLA markers that any two people have in common. HLA matching is usually based on either eight or 10 HLA markers. The more markers two people share, the better the match.

Who is likely to be an HLA match?

The most likely place to find an HLA match is among siblings who have the same mother and father. 

You have a 25-per cent chance of inheriting the same HLA markers as your sibling (an HLA-identical match). You have a 50-per cent chance of inheriting half of the same HLA markers as your sibling (a haploidentical match). You have a 25-per cent chance of inheriting none of the HLA markers your sibling inherited. 

How do we find the best HLA match?

When a doctor recommends a bone marrow transplant, the patient, their siblings and sometimes their parents will have samples (a blood draw or a swab of the inside of the cheek) collected for HLA typing. These will be tested in a lab. 

If a relative is an identical match, the lab will do further testing to be absolutely sure that they are the best match possible. If no sibling is a good match, the doctor may ask to test other family members. Your parents and children have the next best chance of being closely matched with you. 

How Are HLA Genes Inherited?

Biological parents always share half of their HLA proteins with their children. This is also called a “half match.” Conversely, a child always is a half match with their parents. 

A child would share half of the colours on his cells with each of his parents. Siblings who share both parents are most likely to be an identical HLA match. Such siblings have a 1 in 4 chance of being a perfect HLA match (with perfectly matching coloured strings). 

Because the HLA genes are located close together on your DNA, they are usually inherited as a group you inherit a whole set of colours not just one individual colour at a time. 

Your HLA type is composed of the set of HLA genes you inherited from your mother and the HLA genes you inherited from your father. In our analogy, the HLA genes contain information about the "colour of the strings" your cells will have.

What is the cost of the HLA Typing Test?

The cost of the HLA Typing Test is Rs.8000

Is HLA Typing the Same as Blood Typing?

No. HLA typing is much more complicated than blood typing because there are many more HLA markers that make a person's cells unique. There are only eight basic blood types, and many people can safely receive more than one type of blood. To receive only blood from a person, you do not need to be an HLA match, because HLA is not present in red blood cells.

How Is It Performed?

Allele-level resolution data at primary HLA typing is ideal for most histocompatibility testing laboratories. Many high-throughput molecular HLA typing approaches are unable to determine the phase of observed DNA sequence polymorphisms, leading to ambiguous results. 

The use of higher-resolution methods is often restricted due to cost and time limitations. Here we report on the feasibility of using Pacific Biosciences’ Single-Molecule Real-Time (SMRT) DNA sequencing technology for high-resolution and high-throughput HLA typing.

This method has the potential to revolutionize the field of HLA typing. The clinical impact of achieving this level of resolution HLA typing data is likely to consider, particularly in applications such as organ and blood stem cell transplantation where matching donors and recipients for their HLA is of utmost importance.