Pre-implantation Genetic Diagnosis (PGD) is an application used to detect genetic problems in embryos as well as determine the gender of the embryo. It has also become a method that can be used for healing purposes. HLA (Human leukocyte antigen) typing application in embryos is becoming more common method used in PGD.
HLA typing is most important when genetic illnesses are present in children and they are in need of a donor from a sibling, who qualifies for HLA typing, couples who already have a child and are in need of a bone marrow transplant or cord blood stem cells for them.
Couples in need of HLA typing undergo the IVF process and go through the fertilisation of the embryos, the PGD (Pre Genetic Diagnostics) is carried out on the embryos` and the HLA typing is checked to see which embryo is a match (HLA compatibility), to a sibling in need of a transplant. If the IVF treatment is successful, the birth of a resulting child from the IVF cycle can go on to collect and the stem cells from the cord and help their sick sibling regain their health. This approach is simply called “HLA typing in embryos”.
If couples are also carrying a known genetic disease, they can have healthy babies with HLA typing method so that they are given a high chance of having a healthy child.
HLA typing method in embryo is an increasingly new method of treatment and preferred approach especially in the diseases that treatment is possible with the aid of stem cell transplantation such as thalassemia, leukemia, Fanconi Anaemia, Wiskcott Aldrich syndrome. Without HLA typing in embryos it is extremely difficult to find a suitable donor is in the close relatives of the individual.
HLA typing can only be performed in the early stages of a formed pregnancy as the development of the embryo is not possible to be checked or followed if pregnancy occurs naturally. IVF is the only appropriate method, cell samples from embryos are attained in the pre-pregnancy period to perform HLA typing in embryos, and only then can it be determined which is the suitable embryo donor match for transfer.
HLA typing in embryos is not a method performed alone in this regard; in fact it includes a multi-stage process that should be planned in conjunction with IVF:
- Firstly, there is preliminary preparation (set up process) in which blood or tissue samples are taken from couples and their sick children for cross checking. This is very important to obtain the genetic information before beginning IVF treatment;
- Once the samples are checked and results are ascertained then couples can look to begin their IVF treatment;
- Once the stimulation process is completed viable eggs are collected and the sperm injected into them, they go to fertilise and develop into embryos.
- The resulting embryos are examined in terms of HLA compatibility (in terms of existing genetic diseases) with the sick sibling that stem cell transplantation is planned;
- Once the results from the PGD are obtained, it is then clear as to which embryo is suitable for transfer for the chance of a viable pregnancy that can lead to becoming a viable donor for their sibling.
Under appropriate conditions, the genetic preparation needed is anywhere from 2-4 weeks; in vitro fertilization (IVF), obtaining embryo and transferring the embryos to the uterus the appropriate embryo after analysing genetically procedures takes approximately 3 weeks.
Chances of success in treatment are directly related to the number of eggs collected and how the quality of embryos develops. Not only are we in need of good quality embryos but also for embryos that genetically match and suitable for transfer.
Theoretically, 25% of the analysed embryos are expected to be HLA compatible with the sick sibling. This rate is decreased to the level of 18% in the presence of an existing single-gene disorder. Nevertheless, these rates are general rates and finding the appropriate embryos and the obtaining pregnancy may show significant differences between the couples statistically.
The treatment of the sick sibling can be provided by the umbilical cord and the blood stem cells obtained at birth or bone marrow stem cells that can be obtained when the baby reaches a certain level of development to with stand treatment.