By: Iqra Shaukat, Hunza Asghar and Iqra Afzal
In Vitro Fertilization is the removal of ovum from female ovaries and taking sperm from males, and then combining them in liquid medium in laboratory under specialized conditions. The resulting embryo is implanted into mother’s womb. This modern reproductive technology proves to be very useful for treating infertility and prevention of genetic disorders.
Different methods are used in order to obtain eggs from follicles. These eggs are then grown in nutritive media and then incubated so that they become mature. Sperms are taken from either testes or semen fluid of man. Sperms directly added to mature eggs and incubated overnight that leads to fertilization. The technique used for testing embryos created through IVF is pre implantation genetic diagnosis.The basic protocol of this technique is obtaining sample from suitable embryos and then testing of genetic material is done for abnormalities. Embryos with defective gene from any of the parents is then destroyed while embryos that are free of problematic genes are implanted in the womb.
In vitro fertilization accompanied by PGD (Pre-implantation Genetic Diagnosis) is for determination of possibility of developing diseases like Huntington’s disease that is inherited disease due to defective gene in which nerve cells are progressively broken down.
Genetic screening is done in PGD where anomalies and mutations are detected through difference in embryo and parent’s genetic makeup. Sometimes analyzing polar bodies are used for testing mothers egg. Haploid eggs are generated from them. Polar bodies and eggs until fertilization are stuck to each other. Then polar bodies are checked. If defective gene is in polar bodies, then healthy gene is retained in egg. The limitation of this procedure is it works only when mother is at risk.
Once healthy embryosare formed, then there is implantation of either one or two embryos that is done only after discussion with parents. But nowadays it is believed that there are higher chances of success of pregnancy with single embryo.
PGD is developed in humans for the first time in UK. Yet it so controversial, thousands of cases are reported every year.
This example truly illustrates how IVF can prevent from genetic disorders. Jennifer leyton had a family history of Huntington’s disease. As Huntington’s disease is autosomal dominant so there are 50% chances of passing it to off springs. She didn’t want to take risk and turned to PGD. She took services of genetics and IVF institute for this purpose.First of all, IVF is done followed by genetic testing of embryo to check whether resulting embryo is with defective gene or not. She didn’t even know whether she herself carries that defective gene. During all this procedure, she undergoes all the physical ordeals. In second attempt, she became pregnant and healthy twins were born to her. Taking inspiration from leyton’s and many other stories, different fertility clinics around the world are offering PGD so that serious disorders shouldn’t be passed to next generations.
IVF-PGD is also applicable in treatment of Alzheimer’s disease (early onset) that is degeneration of brain tissues leading to memory destruction. For testing of single cell, appropriate genetic markers are used. Embryos are basically screened by exclusion testing process. Based on family history, genetic markers are carefully analyzed that allows the selection of only unaffected embryos without revealing either that mutation is present in man or not.
Breast cancer that is hereditary can use PGD as feasible option. Breast cancer is caused due to presence of BRCA1 and BRCA2 genes. 60-80% chances of cancer are there in off springs if one of these genes is present in mother. Detection of genes by PGD is done so that embryos that are selected don’t have higher risk of cancer.
It is considered better than “three-parent” technique which is similar but more controversial.Although IVF along with PGD is helpful in preventing genetic disorders but there are less chances of pregnancy. The Oxford researchers who had presented their works in fertility field proposed that those embryos with high mitochondrial DNA will not produce pregnancy. Out of eight embryos only one will produce pregnancy. There is one percent rise in success rate of IVF. But inspite of this, its benefits are much more.