What is Clinical Genetics?
Clinical Genetics is the medical speciality that provides a diagnostic service and "genetic counselling" for individuals or families with, or at risk of, conditions that may have a genetic basis. Genetic disorders can affect any body system and at 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.
A Comprehensive Overview of Genetic Disorders
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, etc.
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 is defective.
When to Consider Genetic Testing
Pregnancy
Recurrent pregnancy loss
Family history of Genetic disorder
Infertility
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 on such a genetic problem.
It is the most commonly 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. (Triple test used to be done earlier is now obsolete)
Newer tests like NIPT (Non-Invasive Pre-Natal) test can be done from 10 weeks onwards.
It is slightly more expensive but has much more sensitivity and also tests all 23 pairs of chromosomes.
In high-risk groups, further confirmations of PND (Pre-natal Diagnosis) for that particular disorder can be done by CVS (Chorionic Villous Sampling) or Amniocentesis.
We must remember, a specific diagnostic test does not exclude every possible physical or intellectual condition that could affect your baby.
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 reasons for abortion is either a genetic problem in the parents or in the foetus.
All such couples who experience repeated pregnancy losses must undergo at least a Karyotype evaluation from the blood.
Women
2 consecutive miscarriages
Women
3 or more pregnancy loss
Aborted tissue must be examined for genetic defects. At IHR, we do a 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, a couple can opt for PGT (Pre-implantation Genetic Testing)
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, the 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, Polycystic kidney, Wilson disease, (the list is endless) which run in the family.
Today science can identify the culprit gene and, with the help of PGT (Pre-implantation Genetic Testing), 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.
May be due to some minor or major genetic problems. If no cause can be found, genetic evaluation can be tried to find the cause.
Azoospermia and Oligozoospermia
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Male partners without any sperms (Azoospermia) or with very low sperm count (Oligozoospermia) may be due to genetic defects such as Y-chromosome micro-deletions.
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Today we can achieve pregnancy with the help of ICSI (Intra Cytoplasmic Sperm Injection) in these cases.
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But unfortunately, if this azoospermia or oligozoospermia is due to genetic defects, then these defects will be carried over to all male children.
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In many azoospermic cases, genetic tests may predict the possibility of getting sperm from the testis.
Recurrent IVF Failure
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May be due to a genetically defective embryo or endometrium.
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Today, we can identify these defective embryos with the help of PGT (Pre-implantation Genetic Testing) and NGS (Next Generation Sequencing), and transfer only the healthy embryos, this significantly improves the chances of pregnancy.
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Defective endometrium can be identified by a newer technique called ERA ( Endometrium Receptivity Array).
Elderly females or females with low ovarian reserve
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Have a higher chance of having defective embryos resulting in failed IVF or abortions or abnormal babies.
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PGT-A (Pre-implantation Genetic Testing-Aneuploidy) and NGS (Next Generation Sequencing) is highly recommended.
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However, we must remember these females may not develop any blastocyst or all her embryos may be defective.
