Savior Child to treat inherited diseases in the family
Creating a Savior Child August 2019 by Liat Ben-Senior,
When parents have a child with a serious illness, they face heart-wrenching treatment decisions. For those families with a child that requires a stem cell transplant, often there is the additional hurdle of finding a donor for the transplant. A successful transplant requires an HLA match between donor and recipient. However, the probability of finding a suitable match among family members is only 30% overall. Among siblings, the chances of having a perfect HLA match range from 13% to 51% in the United States, depending on patient age and ethnicity. If members of the family do not match, the next options are to seek a match from the registries of unrelated adult donors, or from a registry of donated cord blood. But another factor parents need to consider, is that stem cell transplants have fewer complications and better survival rates with donors who are not just a match on the HLA types, but who are related to the patient. Given these considerations, some parents explore the possibility of conceiving another child that will be an HLA match to their sick child. This is often called a “Savior Sibling”. When the savior child is born, its umbilical cord blood can be saved as a source of stem cells for the patient in need of a transplant. Creating a savior child is not so simple as just getting pregnant and hoping for the best. The natural chances that another baby will be an exact HLA match to an older sibling are only 25%. Moreover, if the sick child has a hereditary disease, it is important to ensure that the next child does not inherit the genes that carry it. What is Preimplantation Testing? Preimplantation Genetic Testing (PGT) refers to the genetic profiling of embryos. It is used to screen embryos for genetic diseases or chromosomal abnormalities. First the parents must conceive embryos through in-vitro fertilization (IVF) procedures. From each embryo, PGT takes a biopsy of only a few cells and conducts a genetic analysis. This analysis can search to exclude embryos carrying a genetic variant that causes a hereditary disease, and it can search to find embryos that are an HLA match to a sibling. Preimplantation genetic testing can be considered as a form of prenatal diagnosis. Preimplantation genetic testing was first introduced in 1990 by selecting female embryos to prevent the birth of male patients affected with X-linked recessive disorders. The PGT allows diagnosis at three levels: chromosome abnormalities/aneuploidy (PGT-A), structural chromosomal abnormalities (PGT-SR), and single gene diagnosis and HLA typing (PGT-M). Many fertility clinics are now offering PGT testing as a tool to improve IVF outcomes, to avoid the occurrence of known lethal or severely disabling inherited genetic diseases, and also as a way to avoid recurrent implantation or pregnancy failures. Preimplantation genetic testing offers parents a way to ensure their children will not be affected by a genetic disorder without facing the risk and consequences of terminating the pregnancy. Foundation. https://parentsguidecordblood.org/en/news/creating-savior-child