November 21, 2020 2:28:44 pm
By Dr Gauri Agarwal
Having a child is one of the biggest joys of life. However, there may be some genetic diseases that parents can pass on to the unborn/newborn child. This invariably creates a lifelong chain of actions involving treatment and resultant psychological distress. However, scientific advancements in the field of reproductive genetics have made it possible to minimise that chance to near zero. Known as preimplantation genetic diagnosis (PGD), the testing helps identify as many as 400 genetic defects in five-day-old embryos before they are transferred to the mother’s womb.
Diseases where PGD can help
PGD is a gamechanger in detecting genetic disorders at the embryonic stage and helps the parents to continue with their dream to have a healthy child. It helps those who are suffering or are carriers of hereditary diseases like thalassemia and sickle cell anaemia also realise their dream of parenthood without any risk to the child. Combining in-vitro fertlisation (IVF) with preimplantation genetic screening or PGS (testing embryos from presumedchromosomally normal genetic parents for aneuploidy) and PGD (testing embryos from parents, one or both, with known genetic abnormality) also help couples with history of multiple failed IVFs, or multiple missed abortions or miscarriages.
PGD is helpful in people who have a family history of autosomal recessive inheritance disorders where the embryo has two copies of an abnormal gene. The diseases in this category are thalassaemia, sickle cell anaemia, haemophilia, cystic fibrosis, Tay-Sachsdisease, fragile X syndrome, and Huntington’s disease. It is also an equally effective tool for couples with a family history of autosomal dominant inheritance disorders (embryo carrying an abnormal gene from one parent) such as familial hypercholesterolemia, Huntington’s disease, Marfan’s syndrome, and autosomal dominant polycystic kidney disease. Couples who have been diagnosed as carriers of sex-linked genetic disorders, single-gene disorders, and chromosomal disorders will be benefitted by PGD while women who are aged 35 and over and want to be a mother, women experiencing recurrent pregnancy loss and those with more than one failed fertility treatment can also opt for PGD to continue with a healthy child.
Understanding PGS and PGD
Preimplantation Genetic Screening (PGS) is a preventative screening measure used to identify an embryo’s chromosomal abnormalities, even if either of the parents have no known evidence of a genetic abnormality. It screens embryos for chromosomal abnormalities such as Down Syndrome and abnormalities in chromosome position, known as translocations. It is beneficial for women aged 38 or more, or have a history of pregnancy loss and recurrent miscarriage or failed IVF or implantation. Preimplantation Genetic Diagnosis (PGD), on the other hand, tests an embryo for a specific gene mutation when one or both parents have been diagnosed with a genetic abnormality.
Case Study: How Odisha’s Padmini and Niranjan had a healthy child
After two years of marriage, Padmini and Niranjan started to plan a family when, during their preconception check-up, both were found to be thalassemia carriers. It meant that while they did not have the blood disorder, there was a 50 per cent chance the newborn would become a carrier while the chance of having the disease was 25 per cent. The couple proceeded with a natural pregnancy but in the 12thweek, Padmini developed anaemia and a few weeks later, she had a miscarriage. Natural pregnancy was a risk not only to the child but the mother’s health as well, and they were not willing to leave it to fate.
After extensive research, they came to know about preimplantation genetic diagnosis (PGD) that can address their concerns as it ensures embryos developed through IVF are tested for genetic abnormality and only the healthy embryos are transferred to the mother’s womb. Almost one-and-a-half years after they first read about it, Padmini and Niranjan became proud parents of a beautiful daughter they named Vaanya.
(The writer is Fertility Expert & Founder, Seeds of Innocence & Genestrings Lab.)
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