Using Preimplantation Genetic Diagnosis to Avoid Passing on Mutations

Defining Key Terms

What is preimplantation genetic diagnosis?

In 2010, Smith LP, Hughes MR, Thirumoorthi I, Proud VK, and Penzias AS conducted a case study on preimplantation genetic diagnosis. PGD is a screening test used to determine if genetic or chromosomal disorders are present in embryos produced through IVF and has been used to decrease or avoid the risk of transmitting identified mutations to offspring. A mutation is when an object is randomly and blindly changed and passed on to the next generation.

About the Couple in the Case

Syndromes and disorders that could possibly pass to their offspring

A 29 year old woman with spondyloepiphyseal dysplasia congenita underwent in vitro fertilization with preimplantation genetic diagnosis. This is an inherited bone growth disorder that results in dwarfism, which is short stature, skeletal abnormalities, and problems with vision and hearing. Adult’s with spondyloepiphyseal dysplasia congenita are just 3 or 4 feet tall, have a short trunk and neck as well as shortened limbs. In addition to this, the woman’s 30 year old husband has Marfan syndrome. This is a genetic disorder that affects the body’s connective tissues which holds all the body’s cells, organs and tissue together. Connective tissue also plays a crucial role in helping the body grow and develop properly. The cause of Marfan syndrome stems from a defect or mutation in the gene that tells the body how to make fibrillin-1 (a protein).

Two mutation-negative embryos were transferred into a gestational carrier, which is a woman who carries and delivers the baby for the couple. The gestational carrier became pregnant with twins and proceeded to deliver two clinically normal newborn babies.

‍Conclusion & Summary

How PGD has helped the couple

Based on statistics, the couple would have a 75% chance of producing an affected embryo. Because of preimplantation genetic diagnosis, two unaffected embryos were selected and transferred safely. Thanks to PGD, the couple was able to test to ensure mutations or disorders weren’t transmitted to their offspring.