Pre-Implantation Genetic Diagnosis
FIRST offers preimplantation genetic testing to screen for aneuploidy (mistakes in cell division that are not compatible with life) or known genetic diseases that are present in a family. For some patients, this testing can increase the probability of having a successfulpregnancy and a healthy baby.
Preimplantation genetic diagnosis (PGD) is a reproductive technology used with an IVF cycle. PGD can be used for diagnosis of a genetic disease in early embryos prior to implantation and pregnancy. In addition, this technology can be utilized in the field of assisted reproduction for aneuploidy screening and diagnosis of unbalanced inheritance of chromosome abnormalities, such as translocations or inversions. Many couples have benefited from the use of PGD. If you answer yes to any of the following questions, PGD may be helpful for you.
Are you a woman over 35?
All women have a risk to have a pregnancy with a chromosome abnormality. This risk increases as a woman’s age increases. Prenatal diagnosis by chorionic villus sampling (CVS) or amniocentesis to test for chromosome abnormalities, such as Down syndrome, is available. Not all couples want to face decisions during an ongoing pregnancy regarding a chromosome abnormality in the fetus. Couples may instead pursue PGD for aneuploidy screening to optimize the chance of having a healthy pregnancy.
Have you experienced several miscarriages?
There are many possible causes for miscarriage. About 50% of first trimester miscarriages are due to a chromosome abnormality. This may be related to a woman’s age or a rearrangement in a parent’s chromosomes that predisposes the couple to conceive pregnancies with chromosome abnormalities. PGD can be performed for either of these possibilities. For women over 35, the greatest risk may be for aneuploidy, a pregnancy with the wrong number of chromosomes, such as Down syndrome. PGD for aneuploidy screening may offer these women a greater chance of a successful and healthy pregnancy. If a parent has a balanced structural chromosome rearrangement, such as a translocation, a different type of PGD is available.
Have you had a prior pregnancy with a chromosome abnormality?
The risk for a pregnancy with aneuploidy (too many or too few chromosomes, such as Down syndrome) increases with maternal age. Following a chromosomally abnormal pregnancy, the risk for a similar problem to occur again in any subsequent pregnancy is elevated regardless of maternal age. For some couples at an elevated risk, it may be difficult to consider conceiving a future pregnancy. PGD for aneuploidy can reduce the likelihood of a chromosome abnormality in a future pregnancy and increases the chance of achieving an ongoing successful pregnancy.
Have you experienced several failed IVF cycles?
IVF frequently enables couples with infertility to achieve successful pregnancies. Some couples, even after numerous IVF attempts, are unable to become pregnant. Some cases of IVF failure are due to the transfer of embryos with chromosome abnormalities. PGD for aneuploidy can reduce the likelihood of a chromosome abnormality in a future pregnancy and increases the chance of achieving an ongoing successful pregnancy.
Are you having trouble conceiving due to a low sperm count?
IVF pregnancies conceived with a sperm count of less than 20 million/mL or following NSA (Non-Surgical Sperm Aspiration) or TESE (Testicular Sperm Extraction) may produce a higher percentage of chromosomally abnormal embryos. Couples who are planning an IVF cycle due to a low sperm count or who are using NSA or TESE may elect PGD for aneuploidy to reduce the chance of a chromosome abnormality in a future pregnancy and to increase the chance of achieving an ongoing successful pregnancy.
Do you or your partner carry a structural chromosome rearrangement?
A member of a couple may carry a balanced translocation (exchange of chromosome material between two or more chromosomes), a Robertsonian translocation (the joining of two chromosomes) or other structural rearrangements. This increases the risk for a pregnancy with an unbalanced chromosome complement, which can cause birth defects, mental retardation, and/or miscarriage. PGD for structural chromosome rearrangements allows couples to decrease these risks and to increase the chance of a healthy ongoing pregnancy.
Do you or your partner have an autosomal dominant genetic disease such as Marfan syndrome?
A person who has an autosomal dominant genetic condition has a 50% chance of having a pregnancy with the same condition. Prenatal diagnosis by amniocentesis or chorionic villus sampling often allows diagnosis of the genetic disease during pregnancy. However, many couples do not want to be faced with making a decision regarding the outcome of their pregnancy. PGD is available for many autosomal dominant genetic disorders.
Do you have a family history of Huntington disease?
Huntington disease (HD) is an adult onset disorder involving progressive motor disability, cognitive decline, and personality changes. Because this is an autosomal dominant condition, a person with a parent with HD has about a 50% risk of developing HD. Many couples want to prevent having a child that will develop HD, but do not want to face the decision of prenatal testing or making a decision about their pregnancy. Often, individuals do not know if they have HD when they are family planning because the average age of onset of clinical symptoms is 40 years old. These couples may want to prevent having a child with HD, but not know if they carry the HD gene. Non-Disclosing PGD for HD can help these couples decrease the chance of conceiving a pregnancy with HD while not identifying the HD status of the couple.
Do you or your partner carry a recessive genetic disease such as cystic fibrosis?
Couples who carry a mutation for the same autosomal recessive genetic condition have a 25% chance to have a pregnancy with this genetic disease. Prenatal diagnosis by amniocentesis or chorionic villus sampling often allows diagnosis of the genetic disease during pregnancy. However, many couples do not want to face the decision of ending an ongoing pregnancy for a genetic disease. PGD is available for many autosomal recessive genetic disorders.
Do you carry an X-linked genetic disease such as hemophilia or Duchenne Muscular Dystrophy?
X-linked diseases are carried by women, but generally manifests in males. Women have two X chromosomes and can carry a mutation on one X chromosome that can be passed on to their children. Half of their sons will inherit the mutation and have the disease. Half of their daughters will inherit the mutation and thus be carriers like their mother. Carrier females have no clinical symptoms for many, but not all, X-linked genetic diseases. Since only boys are affected for most X-linked genetic diseases, couples can elect PGD for gender determination to have a female, thus reducing the chance of having a child with an X-linked genetic condition. In addition, PGD for the specific disease may also be available.
Do you want to balance the gender in your family?
Even though each pregnancy has a 50% chance to be male and a 50% chance to be female, some families have more children of one gender. PGD for gender determination can help these couples have a child of the underrepresented gender in their family.