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Candidates for Embryo Biopsy and PGD include:
- Women over 34 years of age: Women are born with all the eggs they will ever have, and as a woman ages, her eggs are exposed to this ageing process as well. Therefore, the chance of conceiving a chromosomally abnormal offspring increases with age. Overall, the risk of aneuploidy increases from 1 in 385 at age 30, to 1 in 179 at age 35, to 1 in 63 at age 40, and at the age of 45 the chance of delivering an affected child is 1 in 19. By utilizing PGD with IVF it has been learned that in fact as many as 20% of embryos from women aged 35 to 39 are affected, and almost 40% of embryos from women over 40 are affected. Most of these embryos, if replaced into the uterus, will either not implant or will miscarry. These are considered to be the main reasons why the pregnancy and birth rates in women 40 years of age and over are so low. Prior to PGD, larger numbers of embryos were replaced into the uterus in order to increase the chances of conception. Prenatal testing after the IVF cycle is still strongly advised, since this would confirm the prognosis for a normal offspring. It is also possible that an abnormal embryo may be incorrectly identified as normal and replaced into the uterus.
- Woman with recurrent pregnancy loss: A male or female partner may contribute an abnormal chromosome package which can cause a fatal anomaly in some pregnancies, and not in others.
- Couples with a translocation: A translocation is a change in chromosome configuration in which chromosomes are attached to each other (Robertsonian) or pieces of different chromosomes have been interchanged (reciprocal). Approximately 1 in 900 individuals have a Robertsonian translocation, involving chromosomes 13, 14, 15, 21, 22. Approximately 1 in 625 individuals have a reciprocal translocation. A karyotype of both partners may be done to identify the presence of a translocation. Couples with a translocation may experience recurrent pregnancy loss, or have an offspring with mental of physical problems. In a balanced translocation, when there is no extra or missing chromosome material, and the break in the chromosome does not disrupt gene function, the individual is unaffected. Carriers of balanced translocations may be affected by cryptic congenital malformations, which may or may not be related to the inherited condition. With an unbalanced translocation, one in which there is missing or extra chromosome material, individuals will typically be unaffected, though some do have reduced fertility. However, there is a risk that the egg or sperm of that individual can have an unbalanced translocation, resulting in an embryo being unbalanced. This may cause failure of implantation, recurrent miscarriage, or an offspring with mental or physical problems.
- Couples with autosomal dominant diseases in which 50% of embryos would be affected. Couples who have a family history of, or are carriers of, or affected by an inheritable disease.
Couples with repeated IVF failure.
- Couples with a history of infertility may be able to identify an etiology, and therefore choose the appropriate treatment.
- Couples at risk for offspring inheriting a life-threatening disease, a disease of late onset (Huntington’s), may be better able to plan, choose appropriate treatment options, or accelerate the screening process (such as early screening for breast cancer)
- Couples desiring an offspring with stem cells that are an HLA match for an affected offspring with a fatal disease.
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