“Integrated Approach: Utilizing Biomarkers, Non-Invasive Prenatal Screening (NIPS), and Prenatal Diagnosis for Comprehensive Fetal Assessment” : CGC LAKSHITA CHAUHAN

1. Specialisation:
Preconception, Prenatal, Postnatal, Peadiatric, Neuro, Onco – Pre
and Post-test counselling.
Communicate highly sensitive, distressing and complex finding,
Implication of the test, benefits, and limitations and facilitating
unbiased decision-making.
Using a customised non-directive counselling approach to
support the patient in coping with the report findings.
Work as a part of a multidisciplinary team to resolve queries
pertaining to genetic reports and provide the best in class
support.
CGC Lakshita Chauhan
Army Hospital Research & Referral, New Delhi
Consultant Genetic Counselor
Pathkind Diagnostics Pvt. Ltd.
Board certifies Genetic Counsellor
Major Accomplishments
First Genetic Counsellor of Indian Armed Forces for more
than 5 years.
• Worked with National Inherited Diseases Administration
(NIDAN) Kendra
Department of Biotechnology as. a first Genetic Counsellor,
India
• Set up- First genetic clinic and lab in Indian Armed forces
with Medical Geneticist.
• Signatory authority on Sanger, HBB sequencing and Exome
sequencing reports of Indian Defence forces
• No. of research articles, case reports published.

2. “Integrated Approach: Utilizing Biomarkers,
Non-Invasive Prenatal Screening (NIPS),
and Prenatal Diagnosis for Comprehensive
Fetal Assessment”
CGC LAKSHITA CHAUHAN
BOARD CERTIFIED GENETIC COUNSELOR
ARMY HOSPITAL RESEARCH AND REFERRAL
CONSLT. PATHKIND LABS

3. PRENATAL SCREENING

4. Stages of Prenatal Period
0-12 wks 13-24 wks 25-36wks

5. Why Prenatal Testing?
•Prenatal testing can provide
valuable information about the
baby's health.
•To Understand the risks and
benefits, and how prenatal testing
might affect prenatal care.

6. TYPES OF
PRENATAL
TESTING
Prenatal testing includes both screening tests and
diagnostic tests.
➢Screening tests
○ Prenatal screening tests can identify whether the
baby is more likely to have certain conditions
○ Usually, can't make a definitive diagnosis
○ Screening tests pose no risks for mother or baby
○ Cost effective & easily available
➢Diagnostic tests
○ A more invasive prenatal diagnostic test
○ The only way to be sure of a diagnosis
○ Some tests carry a slight risk of miscarriage
○ less cost effective & performed via experts

8. PRENATAL TESTING
DIAGNOSTIC
SCREENING
BIOCHEMICAL +
SOFT MARKERS
NON-INVASIVE
PRENATAL
SCREENING
INVASIVE TESTING
DUAL/PENTA
MARKER- 1st
TRIMESTER
TRIPLE/QUADRUPLE-
2nd TRIMESTER
CHORIONIC VILLI
SAMPLING- 11-13wks
AMNIOCENTESIS -
16-18wks

9. Screening Strategy​ Time of
Test(in Weeks)​
Markers Used​ DR(%)​
FIRST TRIMESTER SCREENING​
Early Biochemistry​ 9-10^+6​ MA+hCGB, PAPP-A​ ~60-65​
COMBINED FIRST
TRIMESTER
SCREENING​
11-13^+6​ MA+hCGB, PAPP-A+NT​ ~90-91​
11-13^+6​ MA+hCGB, PAPP-A+NT​
+NB+tricuspid flow+facial angle+Ductus
Venoses
~95%​
Early Biochemistry with
NT​
9-10^+6​ MA+hCGB, PAPP-A​
~93-94​
11-13^+6​ NT​
SECOND TRIMESTER SCREENING​
Triple Test​ 15-21^+6​ MA+AFP,hCGB, uE3​ ~65-70​
Quadruple Test​ 15-21^+6​ MA+AFP,hCGB, uE3​
,Inhibin-A​
~70-75​
(GA/ Trimester) BIOCHEMICAL MARKERS

10. •
Dual or Double Marker Test (with or without NT)– This
includes
1. Free β hCG (Free Beta Human Chorionic Gonadotropin)
2. PAPP - A (Pregnancy Associated Plasma Protein – A)
Free β hCG (Free Beta Human Chorionic Gonadotropin)
• Human Chorionic Gonadotropin (hCG) glycoprotein
hormone normally produced by placenta during pregnancy
• Very early in pregnancy, it is the substance used in
pregnancy tests
● Increase hCG - Trisomy 21
● Decrease hCG - Trisomy 18
PAPP - A (Pregnancy Associated Plasma Protein – A)
• Important pregnancy protein
• Reduced PAPP-A : Trisomy 21 or Trisomy 18 is present
First Trimester
Screening -
Markers

11. •Duration: 10W0 to 13W6D
•Eligibility: All women who present for their first prenatal
visit between 10 to 13W6D.
Conditions :
•Down’s Syndrome – Trisomy 21
•Edwards Syndrome - Trisomy 18
•Patau's syndrome - Trisomy 13
IDEAL TIME FOR FTS
•NT measurement: 11 to 13+6/7 weeks
•Serum markers - PAPP-A, free beta hCG: 10-13+6/7
weeks
•
First Trimester
Screening

12. Risk Assessment:
➔ HIGH RISK (>1 in 10) - Offer
Invasive testing
➔ HIGH RISK (>1 in 250) - Offer
NIPS/Invasive testing
➔ INTERMEDIATE RISK (1 in 50- 1 in
999) - Assess Nasal
bone+tricuspid flow+facial angle+D
uctus Venosus​
➔ LOW RISK (<1 in 1000) - Back to
routine scans with second trimester
USG
FIRST TRIMESTER SCREENING

13. •
Quadruple Marker Test – This includes
1. Free β hCG (Free Beta Human Chorionic Gonadotropin)
2. AFP (Alpha-fetoprotein)
3. uE3- (Unconjugated Estriol)
4. Inhibin A
● Alpha-fetoprotein (AFP), a protein made by the developing baby
● Human chorionic gonadotropin (HCG), a hormone made by the
placenta
● Estriol, a hormone made by the placenta and the baby's liver
● Inhibin A, another hormone made by the placenta
Second Trimester
Screening -
Markers

14. Duration: 15W0 to 21W6D
•Eligibility: All women who present for their first
prenatal visit between 15 to 21W6D.
Test can be offered
• Triple Screening
• Quadruple Screening
•The Quad Screen adds a fourth substance
called inhibin A. It leads to the detection of:
•• 70% to 75% of Down syndrome cases​
•• 60% of trisomy 18 cases
•• 80% of open neural tube defects
•
Second
Trimester
Screening Test

15. • Sensitivity (Sn): percentage of affected
pregnancies that are screen positive.
• Specificity (Sp): percentage of individuals with
unaffected pregnancies who screen negative
• Positive predictive value (PPV): likelihood that
a person with a positive test actually has an
affected pregnancy
• Negative predictive value (NPV): likelihood that
a person with a negative test does not have an
affected pregnancy
•PPV and NPV are dependent on disease
prevalence
Important test
characteristics
of Screening
tool:

16. https://www.youtube.com/watch?v
=hKNNJeV9roI
NON-INVASIVE
PRENATAL SCREENING

17. 1. Is also known as non-invasive prenatal testing (NIPT)
2. Uses circulating cfDNA derived from the placenta present in
maternal blood to assess aneuploidy risk at ~10-11 weeks
gestation
4. Has a very high detection rate, positive predictive value and very
low false positive rate, for most conditions screened
3. Is available for all the pregnant women regardless of their age.
5. Is a very sophisticated screen, however there are important
limitations
Facts about prenatal screening by
cell-free DNA

18. Increased risk associated with increased
maternal age at delivery
Edward syndrome (trisomy 18)
~1 in 6,000 live births
~1 in 8-15,000 live births
Down syndrome (trisomy 21)
Patau syndrome (trisomy 13)
~1 in 700 live births

19. SCREENING - Most Common Conditions

20. What if markers are at high risk?

21. NIPS Advantages
• Reduces number of invasive procedures
• Reduces risk to fetus
• Low false positive rate
• High detection rate
• Reduces anxiety in pregnancy
• Looks at all chromosome aneuploidies
• Primary or secondary screen options
• Works for donor ova pregnancies

22. Recommendations

23. NIPS vs Conventional Prenatal Screening
Screening test Detection rate / Sensitivity
for T211,4
False Positive Rate for
T211,4
Positive predictive
value for T212,3
FTS 80-85% 3-9%
~4%
FTS+ NT/NB 85-90% 2-4%
Quad 75-85% 5-10%
SIPS 80-90% 2-7%
cfDNA >99% <0.1% ~80% for all
populations (high
and low risk
women)

24. Prenatal Diagnosis
INVASIVE TESTING

25. INVASIVE TESTS

26. The need for testing?
• According to March of Dimes (MOD) Global
Report on Birth Defects, worldwide 7.9 million
births occur annually with serious birth defects
and 94% of these births occur in the middle and
low income countries.
• In India birth defects prevalence varies from 61
to 69.9/1000 live births.
 8 million with BD (worldwide)
 1.3 crore children born with BD very year in INDIA

27. When to suspect Genetic disorder
 Advanced maternal age
 Recurrent offspring loss
 Previous child with confirmed or suspected genetic
disorder
 Multiple fetal anomalies
 Soft markers
 Abnormal aneuploidy screen
 Couple with recurrent pregnancy loss or BOH

28. Types of Genetic Tests
•Cytogenetics
Conventional Karyotype
•Molecular Cytogenetics
FISH
MLPA
Chromosomal microarray
•Molecular tests
Sanger sequencing
Next generation
sequencing

29. Library analogy for explaining genetic testing
• Clinical examination
• Observing the outside of
building
– Number of windows
– Doors
– Roof
– Height of the windows
Wikimedia

30. Library analogy for explaining genetic testing
• Karyotype
• Standing in one spot in
the library and looking
at the number of rows
(46 rows, 2 row 1s, 2
row 2, etc… the location
of the rows, large extra
or missing pieces

31. Library analogy for explaining genetic testing
• Microarray =
• Walking through the
library and seeing if there
are extra or missing
shelves
• A shelf may be thought of
as a collection of books or
genes, that are closely
located and extra or
missing shelves would be
called microduplication or
microdeletions

32. Library analogy for explaining genetic testing
• Sequencing
– Next-gen sequencing,
Sanger sequencing
• Reading through the
books word by word,
letter by letter to detect
small changes:
substitutions, extra or
missing words

33. Case Presentation

37.  29-year-old G1P0 woman, in good health
 No significant family history or history of prenatal exposure
 FTS screening was negative
 1 in 2,000 versus her age related risk to have a baby with Down syndrome of about 1 in
1,095
 19 week fetal morphology ultrasound showed ventricular septal defect
(VSD), polyhydramnios and suspected cleft lip and palate
 Patient is seen in Genetics and offered amniocentesis with QF-PCR + CMA
to rule out chromosomal aneuploidies
CASE 3

38.  QF-PCR showed normal
 Chromosomal microarray was offered and the results
showed a 2.54-Mb deletion within 22q11.2
22q11.2 deletion syndrome – DiGeorge Syndrome
Multi-system disorder with variable expressivity
Clinical presentation will vary between affected individuals even within
the same family (variable expressivity)
Caused by a sub-microscopic deletion on chromosome 22
85% of individuals will have the typical deletion size and
about 15% will have smaller atypical deletions within the
critical region
About 93% of affected individuals have a de novo deletion
of 22q11.2 and about 7% have inherited the deletion from
a parent
Cont…

39. Case 4:
 34yrs/F
 G2P2L1A1
 Presented with USG suggestive of
Arthrogryposis
 History : first child had history of
Arthrogryposis (no genetic workup
done).
 Fetal WES – Homozygous ECEL1 gene

40. Case 5
• Preconceptional genetic counselling
• A couple come to your clinic with the concern of first
child is thalassemia major and had a history of frequent
blood transfusion.
How would you proceed?

41. CONFIRMATORY TESTING
 Proband
 Hbb- Gene Sequencing
Parental segregation
Invasive testing – on fetus – Sanger Sequencing
Genetic Counselling

43. Multiple Fetal Anomalies

44. PEARLS OF FETAL GENETIC TESTING
NEVER DO AN INVASIVE TESTING OR
ADVISE TERMINATION ON ISOLATED
SOFT MARKERS OR SCREENING
RESULTS

45. THANK YOU