Genetic Screening As Preimplantation Genetic Diagnosis - Increased IVF Success
By Kellieanne McMillan
An inability to establish or maintain pregnancy is most often attributed to lethal genetic defects of the embryo. For infertile couples and carriers of genetic disease, the option of in vitro fertilization (IVF) can often offer the only viable alternative. Over the last 15 years, advances in molecular genetics has allowed for embryos to be genetically screened prior to implantation. Employing various genetic techniques such as Polymerase Chain Reaction (PCR), Fluorescence in situ Hybridization (FISH) and Comparative Genomic Hybridization (CGH), this process - known as preimplantation genetic diagnosis (PGD) - is now used to identify embryos with a range of genetic abnormalities such as chromosomal aneuploidy, single gene defects and X-lined disorders. This article will discuss some advantages and disadvantages of using this technology in IVF assisted reproduction.
The use of PGD ensures that only healthy embryos are implanted in the womb. This presents a number of obvious advantages. Firstly, it substantially increases the chance of successful pregnancy by eliminating genetic factors which cause subsequent miscarriage. It also avoids the trauma of multiple terminations following unfavorable prenatal diagnoses - a reality that is all too common for couples with genetic disease. Ultimately, as well as diminishing emotional and financial stress of repeated IVF cycles, PGD ultimately prevents the birth of individuals with genetic disease. These individuals would otherwise face a myriad of medical and social problems which would both reduce their quality of life and significantly reduce their life expectancy.
The application of PGD to IVF presents other favorable opportunities. Albeit controversial, embryos can be screened for histocompatibility to identify a match for a sick sibling. This can often be the best opportunity - or indeed the only opportunity - to save the life of the sibling with a terminal illness, although this may often present ethical and moral considerations. Furthermore, embryos rejected for implantation can, with appropriate consent, be donated for medical research. This would help to alleviate the current lack of stem cells which are needed to develop future treatments for inherited disease.
PGD has clear advantages but the process is not without limitations. Many studies indicate that it has little or no effect for mature (age 40+) women trying to conceive. Also, since PCR and FISH usually analyze single cells, there is a possibility of false positive and false negative results - errors which are usually due to multiple cell lines in the early embryo through disjunction at mitosis. Consequently, healthy embryos are occasionally discarded as aneuploidic before they have the opportunity to 'self-correct', a phenomenon known to occur in these so called 'mosaic' embryos.
Other limitations of PGD include failure to detect rare types of polygenic disease, such as those of cystic fibrosis which has over 1000 known mutations. Even the basic cell extraction is in itself technically challenging. The embryo must be held in position by a holding pipette, while the zona pellicuda is breached using a micro-needle before a single cell can removed by aspiration. This is a delicate process which poses a risk of irreversible damage to the developing embryo and requires considerable training. Coupled with the fact that the process is expensive and therefore not available to everyone, it is clear that there are also disadvantages.
TOP IVF Fertility Center
Competitive IVF Pricing High Preg Success. Donor&Surrogates
IVF with Genetic Testing
Preimplantation Geneitc Diagnosis Genetic discovery before pregnancy
Sex Selection using PGD
Fertility & Gynecology Center has better success rates than USA avg
Attain IVF, Call Us Now
Boost Your Chance of IVF Success with Attain IVF.
Infertility Specialist
Personalized Diagnosis & Treatment. Caring Staff. Beverly Hills, CA.
IVF 100% Refund Program
6 Cycles of IVF or Donor Egg Tx for One Fee. Delivery or 100% Refund
Am I at Risk?
Find out if you are at risk for 23 disease & Conditions. Learn More
Umbilical Cord Banking
Bank With The Cord Blood Experts™ Get a Free Information Kit Today!
$89 Home DNA Test
Free FedEx Return w/Kit! Accredited Lab - Fast Results. BBB Member
Fertility Experts in CA
Nationally Recognized Practice IVF, PGD - Excellent Success Rates
Surrogates Wanted
Help Loving Infertile Couples and Earn $25,000+. Apply Now!
Incomparable IVF Success
Affordable rates, Personalized care Sensitive Female Doctors and Nurses
Genetic testing lab
GeneDx Offers testing for more than 200 genetic disorders
PGD may give couples with genetic disease the opportunity to produce healthy offspring but the technologies have potential applications which society may deem ethically questionable. For example, is it morally or ethically sound to 'edit' which children should be born into the world? Will genetically affected embryos always be used in the manner for which consent is given? Should PGD be used for non-medical reasons such as selection for desired traits or gender? These are questions that society must surely address as this technology develops.
Author: Kellieanne McMillan (Glasgow University, BSc Neuroscience
