Pregnancy is a journey filled with milestones, excitement, and decisions. Among the most important decisions expecting parents face are choices related to prenatal genetic testing. With advances in fetal medicine, families today have access to a wide range of tests that provide valuable insights into the baby's health and development.
At Mom & Me Fetal Medicine Centre, we offer a comprehensive ecosystem of genetic testing services. Understanding what these tests check, when they are performed, and how they differ is key to making informed decisions with confidence. Here is a guide to the ten prenatal genetic services offered at our centres.
1. Genetic Counselling
Genetic counselling is the foundation of all genetic testing. It is a supportive, informative consultation with a specialist to review your medical history, family pedigree, and any previous pregnancy findings. The goal is to estimate inherited risks, clarify screening options, and guide families through diagnostic pathways in a compassionate environment.
2. Double Marker Screening
Performed during the first trimester (typically between 11 and 13.6 weeks), the Double Marker is a maternal blood test that measures two proteins: free Beta-hCG and PAPP-A. When combined with the NT (Nuchal Translucency) ultrasound scan, it screens for common chromosomal conditions such as Down syndrome (Trisomy 21) and Edwards syndrome (Trisomy 18).
3. Quadruple Marker Screening
The Quadruple Marker is a second-trimester maternal blood screening test performed between 15 and 20 weeks. It measures four substances: Alpha-Fetoprotein (AFP), hCG, Unconjugated Estriol (uE3), and Inhibin-A. It is commonly recommended for parents who missed first-trimester screening, evaluating risks for chromosomal conditions and open neural tube defects.
4. NIPT / NIPS (Non-Invasive Prenatal Testing)
NIPT is a highly accurate blood screening test available from 10 weeks of pregnancy. It analyzes tiny fragments of cell-free fetal DNA (cfDNA) circulating in the mother's blood. NIPT offers an exceptional detection rate (greater than 99%) for Down syndrome, Edwards syndrome, and Patau syndrome, with a very low false-positive rate.
5. Karyotyping
Karyotyping is a diagnostic test that examines the full set of chromosomes under a microscope. By collecting cells through amniocentesis or CVS, karyotyping maps out the size, shape, and number of chromosomes. It can confirm large numerical abnormalities or structural rearrangements (like translocations) that may affect the baby's development.
6. Chromosomal Microarray (CMA)
Chromosomal Microarray is a high-resolution genetic scan of the fetal chromosomes. It searches the entire genome for microscopic imbalances—deletions or duplications of genetic material (copy number variants) that are too small to be seen under a standard microscope during karyotyping. CMA is particularly recommended when ultrasound scans reveal fetal structural anomalies.
7. Whole Exome Sequencing (WES)
Whole Exome Sequencing is an advanced genetic test that reads the genetic code of all protein-coding regions (exomes) in the fetus's DNA. It is used to diagnose single-gene disorders and rare genetic syndromes when standard chromosomal tests like microarray are normal, but fetal ultrasound shows complex structural abnormalities suggesting a genetic cause.
8. Sanger Sequencing
Sanger sequencing is the gold standard for targeted DNA sequencing. Instead of scanning the entire genome, it targets a specific gene region or mutation. It is ideal for verifying genetic variants identified by larger sequencing runs, or checking if a fetus has inherited a specific gene mutation known to run in the family.
9. Couple Carrier Screening
Couple carrier screening is a genetic DNA test performed before pregnancy or in early pregnancy. It determines if the parents carry silent gene mutations for recessive disorders like Thalassemia, Spinal Muscular Atrophy (SMA), or Cystic Fibrosis. If both parents carry a mutation for the same condition, there is a 25% chance of passing it to the baby, allowing couples to plan proactively.
10. DNA Storage
DNA storage is a biobanking service where purified DNA extracted from prenatal samples (such as amniotic fluid or chorionic villi) is stored long-term in a secure, temperature-controlled environment. This allows families to preserve genetic material for future reference, comparative testing, or advanced diagnostic studies as technology evolves.
Screening vs. Diagnostic Testing: The Crucial Difference
As you explore these options, it is vital to understand the difference between screening and diagnostic tests:
- Screening Tests (Double Marker, Quadruple Marker, NIPT) estimate the probability or risk of a condition. They are non-invasive and carry zero risk of miscarriage, but they cannot give a definitive "yes" or "no" answer.
- Diagnostic Tests (Karyotype, Microarray, Sequencing) confirm the diagnosis with near 100% accuracy. They require collecting fetal cells via amniocentesis or CVS, which carry a very small procedure-related risk.
Making the Right Choice
There is no single "best" genetic test; the right choice is highly individual. It depends on your gestational age, family history, scan findings, personal preferences, and clinical recommendations. Our expert fetal medicine specialists and genetic counsellors are here to guide you through every choice with empathy and clarity.
If you have questions about prenatal screening or need to discuss your results, please schedule a genetic counselling consultation at one of our Bengaluru clinics.
Explore our full range of services or contact us today to book an appointment.