Couples who have trouble conceiving through Assisted reproductive technology (ART) or have an offspring with a genetic disorder are finally finding a ray of hope in Preimplantation Genetic Diagnosis.
Disorders such as thalassemia, cystic fibrosis, sickle cell disease, Huntington’s disease and spinal muscular atrophy can be diagnosed using the preimplantation genetic testing (PGT), which identifies genetically normal embryos in a given cohort for implantation.
Akanksha Hospital and Research Institute headed by Dr Nayna Patel in Anand — known for its surrogacy procedures — successfully conducted preimplantation genetic diagnosis testing of oculocutaneous albinism (OCA) — a rare group of genetic disorders that cause the skin, hair, or eyes to have little or no colour.
The case report titled “Deselection of embryo and live birth of albinism-free baby following preimplantation genetic testing for monogenic disorders”, co-authored by Dr Harsha Bhadarka, Salil Vaniawala and Arpita Patel of Akanksha Institute has been published in the current issue of the Journal of Human Reproductive Sciences. Patel says this was possibly the first PGT for albinism in India.
Patel said, “This was the case of a Nigerian couple married for nine years. They were seeking consultation as they had a four-year-old child suffering from albinism type-OCA 1. As per previous reports, the affected child inherited the disorder due to mutation in OCA1 gene from parents and there was a strong possibility of the obligate asymptomatic carrier in the family. Hence, it was decided to check for a mutation in OCA1 gene… The couple was counselled about the genetic risk, success rates, the risk of misdiagnosis, and the importance of prenatal diagnosis.”
The couple underwent the genetic testing at Akanksha Institute and delivered their baby boy back home in Nigeria earlier this year. “This is the first report of its kind in our country, in which the preimplantation diagnosis of embryos was done to check mutation in OCA1 gene. Nowadays, PGT for single or multiple gene disorders is a well-established reproductive option for couples at risk of transmitting genetic disorders to the offspring…,” said Patel.
While it is still a developing technology in India, Patel, along with her Obstetrics and Gyne-cologist daughter-in-law Dr Molina Patel feel that PGT holds great potential in India. Patel says she is in the process of preparing another case report of a Gujarati couple that eliminated sickle cell disorder before the IVF implantation.
“A couple, who had naturally conceived the first offspring with spinal muscular atrophy, also opted for PGT. Disorders like sickle cell and thalassemia are common in Gujarat and the genetic technology can help couples. We have had couples coming in when they are aware of their family history of a pre-existing genetic disorder or when they have a first child who was born with a genetic disorder where the parents are unaware that they are carriers. The potential that genetic testing technology has in India is immense. IVF doctors must promote genetic testing to reduce the number of ART cycles in couples who are facing issues like miscarriages,” she said.
“The biopsy itself may damage the developing embryo. So couples have to be counselled. The process is conducted in a controlled environment to ensure that the technicians receiving and handling embryos are covered from head to toe as even minor contamination can immediately pass on the DNA of the handler into the embryo,” Patel said.
Molina is currently working on a report of 13 other couples with various rare chromosomal conditions in which the research centre has successfully completed the implantation. In all the cases, PGD-T was successfully applied to detect other rare genetic conditions such as hereditary inclusion body myopathy, ColA4 gene mutation (hematuria) and spinal muscular atrophy in the embryos.
Experts say that embryos are tested through a biopsy on the fifth day to make PGT more clinically significant. However, it may not be successful in eliminating autism. “The chromosome that causes autism is extremely wide and the chances of finding the anomaly in the gene are very difficult. So, PGT cannot help much in cases where couples are looking to eliminate autism,” said Patel.
The deterrent for the common use of the testing, however, is also the cost of the process. “Each IVF cycle costs close to Rs 1.5 lakh and PGT of each embryo could cost Rs 3.5 lakh. It is a costly affair and so it also has to be done meticulously, after adequate counselling and testing of the couples.”
Dr Frenny Sheth, Director of Institute Of Human Genetics, Ahmedabad, says that that PGD has gained importance since several couples are opting for IVF pregnancies due to late marriages. “IVF pregnancies involve multiple embryos and couples have a chance to go for PGD after understanding the advantages of identifying any abnormalities in the embryo. The most viable embryo is chosen and tested for the particular gene for which the defect has to be tested. The process is expensive and so not everyone can go for it but it is gradually gaining importance.”