The NIPS is a non-invasive blood test which helps in identifying chromosomal anomalies such as Down, Edward and Patau Syndrome in the growing foetus. This test extracts the free-floating foetal DNA from the mother’s blood which is assessed to check for the presence of such chromosomal aneuploidies. The foetal DNA is then sequenced using advanced Next Generation Sequencing (NGS) technology to check for these chromosomal disorders. NIPS is a highly sensitive test with 99% accuracy. However, NIPS is a screening test and therefore requires confirmatory invasive testing such as chorionic villus sampling (CVS) or Amniocentesis, in case of a positive screen.
A karyotype test looks at the size, shape, and number of chromosomes in an individual. Chromosomes contain an individual’s genes, which are parts of DNA passed down from their parents. They determine the traits you have, such as height and eye color. People usually have 46 chromosomes, divided into 23 pairs, in each cell. One of each pair of chromosomes comes from the mother, and the other pair comes from the father. If an individual has more or fewer number of chromosomes than 46, or if there is anything unusual about the size or shape of the chromosomes, it could be indicative of a genetic disease. A karyotype test is often used to help find certain genetic defects that could be present in a couple and could be passed onto their future children. It is also a useful test to determine the cause of repeated miscarriages, infertility and individuals having developmental delay and intellectual disability.
Thalassemia is an inherited blood disorder that affects the body’s ability to produce functional hemoglobin in the red blood cells leading to anemia and low levels of oxygen in the bloodstream and requires repeated blood transfusions in the affected individual. It is an autosomal recessive disease which means both copies of the HBB gene show a mutation in an individual. Thalassemia Screening in pregnancy is done to identify couples who are HBB mutation carriers and show a 25% risk of having a child with Thalassemia in each pregnancy. The test screens both partners simultaneously to look for mutations making them carriers of the defective gene. If both partners are found to be carriers, further genetic testing is prescribed which is required for prenatal diagnosis of Thalassemia in the foetus.
The Y chromosome is responsible for male characteristics. Many times there are changes in the chromosome such as deletions or rearrangements. Y chromosome microdeletions are seen in males with severe infertility. Male factor infertility could be in the form of azoospermia, severe to moderate oligospermia, or abnormal sperm morphology and motility in men with a normal physical evaluation. The Y chromosome microdeletions are usually seen in the AZF gene and commonly are in the regions AZFa, AZFb and AZFc in such individuals, chances of natural pregnancy are very low and may need to undergo an assisted reproductive technique (ART) guided pregnancy.
Every individual is comprised of DNA which has specific genes which encode the structural and functional components of every person. This DNA is passed down from the mother and the father to their offspring. Sometimes there are changes in certain genes, called mutations which may give rise to genetic conditions infertility in either of the partner thus making it difficult to conceive. In such cases the exome sequencing test is recommended wherein advanced Next Generation Sequencing sequences all the protein coding genes of the human body and detects any mutation in the genes responsible for causing a particular genetic condition. This test is helpful in detecting genetic conditions such as:
This is a very accurate test and depending upon the result- positive or negative for a gene mutation further testing and guidance regarding pregnancy is given to the couple.
Preimplantation Genetic Screening (PGS) is a genetic screening procedure which helps identify chromosomal aneuploidies in the embryos created during an IVF procedure. This test is important especially when there are first trimester miscarriages during normal pregnancy due to chromosomal aneuploidies. An embryo biopsy is taken wherein a single cell is retrieved from the embryo after 5-6 days of development. The genetic material is amplified and then tested to check for chromosomal aneuploidies. The embryo which does not have any chromosomal aneuploidy is taken ahead and transferred. This test is recommended for:
Preimplantation Genetic Diagnosis or PGD is a technique that enables couples with a particular inherited condition in their family to avoid passing it on to their children. If there is a known genetic condition in the family, it is important to diagnose and do the gene mutation analysis for the same. Once the mutation in the gene is identified, the couple can proceed for an IVF cycle. A biopsy is taken from the embryo after 5-6 days of development and the DNA is amplified. The mutation identified to be causing the genetic disorder is then checked in the embryo sample. The embryo which is negative for the gene mutation is then a mutation free healthy embryo is transferred.
This is a genetic test that is done for the couples to identify if they are at any risk of passing certain autosomal recessive genetic disease to their children. An autosomal recessive inherited disorder is transmitted when parents are asymptomatic carriers of a gene mutation which causes the disorder. ir children. This test screens both partners simultaneously for common autosomal recessive disorders to check if they are carriers for gene mutations. If both partners carry a mutation in the same gene, there is a 25% risk of having an affected child. It is very likely that most people can be carriers of a disease without knowing it.
The Carrier Screening test is recommended for:
Couples can get this test done at any time, be it – before pregnancy or during pregnancy. However, undergoing this test before planning a pregnancy can help the couple make informed decisions.
Multiplex Ligation-dependent Probe Amplification (MLPA) is a specialized genomic test which helps to detect certain specific mutations in a particular gene. Many of the genetic disorders are caused due to deletions and duplication of genes in the DNA as in the case of Duchenne Muscular Dystrophy (DMD). MLPA helps in detecting large deletions and duplications within a gene in a cost-effective and robust manner. In addition, it has the ability to detect small rearrangements and copy number variations (CNV). Diseases that are diagnosed using MLPA includeDuchenne Muscular Dystrophy (DMD)/ Becker Muscular Dystrophy (BMD), Gliomas, Limb girdle muscular dystrophy among others.
Sanger Sequencing is the gold standard for DNA based mutation testing. Every individual is comprised of DNA and the DNA is composed of different genes which encode every structure and function for a human being. Small changes in the sequence of the DNA at single points (point mutations), additions or deletion of small portions (indel mutations) for certain crucial genes may lead to genetic disorders. The Sanger sequencing reads every base pair for an exonic sequence of a gene and detects such mutations. This test is usually used to confirm gene mutations detected through exome sequencing with high sensitivity and specificity.
FISH (Fluorescence in-situ Hybridisation) Fluorescence in-situ hybridization (FISH), is a cytogenetic and a molecular technique that makes use of fluorescent probes, which binds to only those parts of a nucleic acid sequence that are complementary with each other. It is able to detect and localize the presence or absence of specific DNA sequences on chromosomes. FISH has increased sensitivity and resolution as compared to a karyotype test. It is recommended for:
CMA is a high resolution genetic test that can analyse multiple regions of DNA at once. It has the capacity to screen for deletions, duplications, loss of heterozygosity and aneuploidy detection for all chromosomes. It is useful in diagnosing many neurological conditions and analyse POC samples.