DEFINE – Genetic Counselling and Preimplimentation Genetic Diagnosis

What is Genetic Counseling?

Genetic counseling is a course of action of communicating medical aspects about a genetic disorder, especially the information regarding risk of occurrence as recurrence of the disease in the family and preventive options. Accurate diagnosis of the affected member is of paramount importance for genetic counseling. Special genetic investigations like DNA examination and chromosomal examination are basic for many situations and especially when prenatal diagnosis is necessary.

Genetic Counseling Procedure:

A woman may be referred for genetic counseling if pregnant and undergoing prenatal testing or screening. Genetic counselors educate the patient about their testing options and inform them of their results. If a prenatal screening or test is abnormal, the genetic counselor evaluates the risk of an affected pregnancy, educates the patient about these risks and informs the patient of their options.

A person may also undergo genetic counseling after the birth of a child with a genetic condition. In these instances, the genetic counselor explains the condition to the patient along with recurrence risks in future children. In all situations of a positive family history for a condition, the genetic counselor can estimate risks, recurrence and explain the condition itself.

What is PGD?

Preimplantation genetic diagnosis (PGD) is a technique which involves the genetic testing of embryos produced by IVF for deleterious, heritable genetic conditions which are known to be present in the family of those seeking treatment and from which the embryos are known to be at risk.

PGD was developed to allow couples at risk of passing on a serious genetic disease to have children not affected by it. Since its introduction, it has been most widely used to prevent the birth of children with conditions such as Down’s syndrome, Tay-Sachs disease, cystic fibrosis, sickle cell, Huntington’s chorea, and Cooley’s anemia.

When is PGD used?

Most commonly, PGD is used where a associate is aware of the possibility that their offspring will inherit a genetic disease. already though they may not have a problem with infertility, they choose to undergo a stimulated IVF cycle with the aim of producing a number of embryos.

Now, the major application of PGD is in the field of assisted reproduction for aneuploidy screening and diagnosis of unbalanced inheritance of chromosome abnormalities (translocations). The most shared kind of PGD today involves testing of embryos for a panel of the most shared chromosome abnormalities (aneuploidy screening) and using only normal embryos to attempt a pregnancy. Each IVF cycle, consequently, has a better possible outcome, since embryos screened in this way have been shown to have a higher rate of implantation in the uterus, lower instinctive loss rate, and a reduced risk of trisomic offspring (i.e. Down syndrome).

Some families have used PGD to test their embryos to ensure they can provide a bone marrow transplant for a sick sibling. The bone marrow cells for the sick sibling are taken from the umbilical cord blood of the new baby. Using this course of action of tissue typing, these babies are sometimes called ‘saviour siblings’ as they can literally save their sick brother or sister’s life.

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