Clinical Genetics is the medical speciality which provides a diagnostic service and "genetic counselling" for individuals or families with, or at risk of, conditions which may have a genetic basis. Genetic disorders can affect any body system and any age group. The aim of Genetic Services is to help those affected by, or at risk of, a genetic disorder to live and reproduce as normally as possible. Genetic disorders include:
- Chromosomal abnormalities, which cause birth defects, mental retardation and/or reproductive problems
- Single gene disorders such as cystic fibrosis, muscular dystrophy, Huntington's disease and sickle cell disease
- Familial cancer and cancer-prone syndromes such as inherited breast or colorectal cancer and neurofibromatosis
- Birth defects with a genetic component such as neural tube defects and cleft lip and palate
Different types of genetic tests are used, depending on whether an individual’s chromosomes, the protein (product of a gene), or the DNA itself are defective.
In the following conditions it is advisable to undergo genetic evaluation.
All of us desire a healthy baby. Today we don’t have to wait for the delivery to know the health of the baby. Many diseases can be screened and diagnosed during pregnancy.
Down Syndrome is one such genetic problem, and is the most common occurring chromosomal abnormality in humans. Extra genetic material from chromosome 21 is transferred to a newly formed embryo. These extra genes result in physical and mental abnormalities in the foetus.
Each and every pregnancy (irrespective of age or previous healthy child) must be screened for Down syndrome. Blood test and USG (Double marker + Aneuploidy scan = Combined test) at around 12 weeks can tell us whether the foetus has a high risk or low risk of having Down Syndrome.
If the patient comes late in the pregnancy between 16 to 20 weeks, then Quadruple test can be done.
(Earlier Triple test used be done, but is now obsolete and should no longer be done).
Newer test like NIPT (Non Invasive Pre-Natal) test, though slightly more expensive but have much more sensitivity and also test all 23 pairs of chromosomes.
In high risk groups further confirmations (PND : Pre-natal Diagnosis) for that particular disorder can be done by CVS (Chorionic Villous Sampling) or Amniocentesis. We must remember, a diagnostic test does not test for every possible physical or intellectual condition that could affect your baby.
Recurrent pregnancy loss:
Approximately 5% of women experience two consecutive miscarriages and 1% experience three or more pregnancy loss. This may occur due to various reasons. One of the well-established reason of abortion is either genetic problem in the parents or in the foetus.
All such couples who experience repeated pregnancy losses must undergo at least Karyotype evaluation from blood.
Aborted tissue must be examined for genetic defects. At IHR, we do genetic evaluation of the foetus via NGS (Next Generation Sequencing), which gives us far more information about the genetic health of the foetus than conventional Karyotype or F.I.S.H.
In case genetic defects are found, couple can opt for PGD (Pre-implantation Genetic diagnosis) or PGS (Pre-implantation Genetic Screening).
Family history of Genetic disorder
All of us desire a healthy baby physically as well as mentally. Any pregnancy has 3-5% chances of developing some problem which is known as background risk. But some diseases run in family (hereditary). In these cases, next generation has very high chances of acquiring that particular disease due to the defective gene present in the family. We have all heard about the infamous problem of haemophilia which runs in the royal family of the UK. There are so many other problems like Thalassemia, Cystic fibrosis, Sickle cell anaemia, Albinism, Poly cystic kidney, Wilson disease, (the list is endless) which run in the family.
Today science can identify the culprit gene and, with the help of PGD (Pre-implantation Genetic diagnosis), the healthy embryos can be selectively chosen for transfer.
Ideally the parents must visit the clinic before pregnancy. The identification of the culprit gene is challenging and time consuming. However, if the parents come during pregnancy, and if the culprit gene is pre-identified, then (PND : Pre-Natal Diagnosis) can be offered.
In many couples infertility may be due to some minor or major genetic problems. In couples where no cause can be found for infertility, genetic evaluation can be tried to find the cause.
Azoospermia and Oligozoospermia
Male partners without any sperms (Azoospermia) or with very low sperm count (Oligozoospermia) may be due genetic defect in the production of sperm. Today we can achieve pregnancy with the help of ICSI (Intra Cytoplasmic Sperm Injection) in these cases. But unfortunately if this azoospermia or oligozoospermia is due to genetic defects, then these defects will be carried over to all male children. In many azoospermic cases, genetic tests may predict the possibility of getting sperm from the testes.
Recurrent IVF Failure
Infertile couple suffering from recurrent IVF failures may be due to genetically defective embryo. Today, we can identify these defective embryos with the help of PGS (Pre-implantation Genetic Screening) and NGS (Next Generation Sequencing), and transfer only the healthy embryos, this significantly improves the chances of pregnancy.
Elderly females or females with low ovarian reserve
Elderly females or females with low ovarian reserve have higher chance of having defective embryos resulting in failed IVF or abortions or abnormal babies. In this group of patients, PGS (Pre-implantation Genetic Screening) and NGS (Next Generation Sequencing) is highly recommended. However, we must remember these females may not develop any blastocyst or all her embryos may be defective.
For More information, book an appointment with our senior specialist Dr. Deepak Goenka.