PGDlab : For Physicians : What is PGD : Q & A

Cystic Fibrosis (CF) is a condition primarily affecting the lungs and pancreas. The disease is characterized by chronic pulmonary disease progressing to end-stage lung failure. Multiple gastrointestinal abnormalities can occur including malabsorption of nutrients and pancreatic insufficiency. Azoospermia (absence of sperm in semen) occurs in approximately 95% of men with CF, due to absence of or defects in the development of the vas deferens. The only gene known to be responsible for CF is CFTR (cystic fibrosis transmembrane conductance regulator).

CF is inherited in an autosomal recessive manner. Usually, unaffected parents of an affected individual are both identified as being carriers for CF. A carrier has only one identifiable CFTR gene change (mutation). Individuals with the disease usually have two gene changes in the CFTR gene, having inherited one from each parent. There are over a thousand different possible mutations within the CRTR gene. The most common mutation is deltaF508, accounting for approximately 60-70% of identified mutations in carriers.

For families in which both parents have been identified as being carriers for the deltaF508 mutation, PGD can help reduce the chance of having an affected child.

In a PGD cycle, embryos created by IVF are cultured in the laboratory for 3 days at which time they contain approximately 8 cells (Embryos at this pont are called blastomeres). Embryos with normal development on Day 3 are biopsied using micromanipulation techniques. This involves the use of very fine glass needles and tools under microscopic observation and control to remove 1or 2 cells from each blastomere for analysis.

At this early stage of embryological development, the blastomeres are totipotent; they are still capable of forming cells of any organ or tissue. Removal of a few of the cells of the early embryo does not alter the ability of that embryo to develop into a complete, normal pregnancy and child. Data from many years of PGD in animals and approximately 1200 live births in humans indicate that PGD does not lead to an increase in birth defects or chromosomal disorders.

When a PGD biopsy is done, 1-2 cells are removed from the embryo. In order to obtain results of the biopsy, the cell removed must contain a nucleus, as the nucleus contains the genetic information necessary for testing. The presence or absence of deltaF508 is detected on cells prior to implantation to determine which embryos are selected for transfer into a woman’s uterus. Thus, the chance to have a healthy unaffected pregnancy is greatly increased.

Genetics & IVF Institute has developed a new linkage test for CF for couples that carry mutations other than deltaF508. Learn more about Linkage Analysis.

For more information about Genetics & IVF Institute's PGD for aneuploidy,
please call (800) 654-4363 or (703) 698-7355
and ask to speak with the PGD counselor OR email PGD@givf.com.

Please click on the another question for more information.

• Is your patient a woman over 38?
• Has your patient experienced several miscarriages?
• Has your patient had a prior pregnancy with a chromosome abnormality?
• Has your patient experienced several failed IVF cycles?
• Has conceiving a pregnancy been difficult for your patient due to a low sperm count?
• Does your patient or patient's partner carry a balanced structural chromosome rearrangement?
• Does your patient have a family history of Huntington disease?
• Does your patient or patient's partner carry a recessive genetic disease such as cystic fibrosis?
• Does your patient or patient's partner carry an X-linked genetic disease such as hemophilia or Duchenne Muscular Dystrophy?
• Does your patient want to balance the gender in your family?

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