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Home › Conditions › Genetic and chromosomal conditions
CONDITIONS · GENETIC AND CHROMOSOMAL
When a family history or a test result changes the plan.
Some couples carry a chromosome change or a gene for an inherited condition without knowing it. A few simple tests can find it, and then there are clear options for having a healthy child.
- Most couples don't need it
- Simple blood tests first
- Counselling before any decision
- Embryo testing only where indicated
- Number — An extra or missing chromosome (for example XXY)
- Structure — A translocation, pieces swapped between chromosomes
- Single gene — A carrier of thalassaemia or cystic fibrosis
- Y chromosome — Small deletions that stop sperm production
01What genetic and chromosomal conditions affect fertility?
The ones that matter for fertility are chromosome changes in either partner, genes for an inherited condition that both partners carry, and changes on the Y chromosome that affect sperm.
A balanced translocation means pieces of two chromosomes have swapped places. The person is healthy, but eggs or sperm can carry an unbalanced set. Klinefelter syndrome (XXY) affects sperm production. Being a carrier of a condition such as thalassaemia causes no symptoms, but if both partners carry it, each child can inherit it.
02How do they affect fertility and pregnancy?
Chromosome changes can cause repeated miscarriage or failed IVF; carrier status causes no fertility problem but can be passed on; Y chromosome changes can stop sperm production.
Most miscarriages from chromosome errors are random and not inherited. A translocation in a parent is found in a small number of couples with recurrent loss. In men with no sperm or a very low count, a genetic cause is found in some, and it can pass to sons.
Recurrent miscarriage03Who needs genetic testing before IVF?
Genetic testing before IVF is for couples with recurrent miscarriage, a family history or child with a genetic condition, a known carrier result, or a man with no sperm or a very low count.
A karyotype is a simple blood test for both partners. Men with no sperm or a very low count have a karyotype and a Y chromosome deletion test. A man born without the sperm tubes (vas deferens) has a CFTR gene test, and then his partner is tested too. Carrier screening checks whether both of you carry the same condition.
KaryotypingNo sperm: obstructive azoospermia04What are the options if a test is positive?
The options are natural conception with a prenatal test in pregnancy, IVF with embryo testing (PGT-M or PGT-SR), or donor eggs or sperm.
PGT-M tests embryos for a single-gene condition that runs in the family. PGT-SR tests embryos for an unbalanced translocation. Both need IVF, even if you have no fertility problem. Genetic counselling comes first, so you choose with the facts in front of you. [CONFIRM: counsellor in-house or referral]
Honest note
Embryo testing (PGT)PGT-M and PGT-SR are not 100% accurate, so there is a small chance a test gives the wrong answer. A prenatal test in pregnancy is still offered to confirm the result. (What the evidence says)
05When should we get tested?
Before trying, if you know of a condition in the family or have had two or more losses; at the first fertility visit, if his sperm count is very low or zero.
Bring any reports you have: a relative's diagnosis, a child's test, earlier karyotypes or pregnancy tissue results. Tell us if you and your partner are related by blood, because it raises the chance you carry the same condition. Testing before pregnancy gives you the most choices.
Does this sound like you?
If one of these fits, a genetic check may change your plan.
- We've had two or more miscarriages
- A condition runs in our family
- We both carry thalassaemia trait
- His report says no sperm or very few
- We are related by blood
- A karyotype report came back abnormal
None of these? Most couples do not need genetic tests. Start with the usual tests for both of you.
What we do, in order.
- 1
Family history and reports
Who is affected, which test, which result. Both partners.
- 2
Test the right person
Karyotype, carrier screen, Y deletion or CFTR test, chosen by your situation.
- 3
Genetic counselling
What the result means for each pregnancy, and your options, before any decision.
- 4
Choose a route
Natural conception with prenatal testing, IVF with PGT-M or PGT-SR, or donor eggs or sperm.
Your first visit
1
Talk
Your family history, losses and any genetic reports, for both of you.
2
Test
Only the genetic tests your history points to, usually simple blood tests.
3
Plan
What the result means, counselling, and each option in plain words.
4
Treat
IVF with embryo testing if you choose it, or natural conception with prenatal testing.
Questions patients ask
Still unsure? Ask us on WhatsApp — a real person replies.
Who should have genetic testing before IVF?
Couples with recurrent miscarriage, a family history of a genetic condition, a known carrier result, or a man with no sperm or a very low count. Most couples starting IVF do not need genetic tests.
What does it mean if a karyotype test result is abnormal?
An abnormal karyotype means a chromosome is extra, missing or rearranged, and what it means depends on the exact change. Many people with a balanced translocation are healthy and can have children; the next step is genetic counselling.
We are both thalassaemia carriers. Can we have a healthy child?
Yes. When both partners are carriers, each pregnancy has a one in four chance of a child with thalassaemia major, and you can test in pregnancy or choose IVF with PGT-M to transfer an unaffected embryo.
What is the difference between PGT-M, PGT-SR and PGT-A?
PGT-M tests embryos for one inherited condition, PGT-SR for an unbalanced translocation, and PGT-A for the number of chromosomes. PGT-M and PGT-SR are for couples with a known genetic risk; PGT-A is considered only in selected cases.
Why test for a Y chromosome deletion?
A Y chromosome microdeletion can explain no sperm or a very low count, it tells us whether sperm retrieval is likely to find sperm, and it passes to any son.
Is PGT legal in India?
Yes, the ART (Regulation) Act 2021 allows pre-implantation genetic testing to screen embryos for known, pre-existing, heritable or genetic diseases. Choosing an embryo's sex is illegal.
In their words, not ours.
Geetha M.
· Google
She prescribes only the very necessary investigations and medications, maintaining high standards and ethics.
Sources (4)
- HFEA (UK fertility regulator): Pre-implantation genetic testing for monogenic disorders (PGT-M) and chromosomal structural rearrangements (PGT-SR)
- American Urological Association and ASRM: Diagnosis and Treatment of Infertility in Men: AUA/ASRM Guideline
- RCOG: Recurrent Miscarriage (Green-top Guideline No. 17)
- Government of India (via PRS Legislative Research): The Assisted Reproductive Technology (Regulation) Act, 2021
TEST
Karyotyping
The test, the report, and how long it takes.
TESTEmbryo testing (PGT)
PGT-M, PGT-SR and PGT-A, and who each is for.
TREATMENTTREATMENT · Needed for embryo testing, even without a fertility problem.
Needed for embryo testing, even without a fertility problem.
TREATMENTTREATMENT · When sperm are very few or retrieved by surgery.
When sperm are very few or retrieved by surgery.
Bring the report. We'll explain what it means.
Send us the test name or a line about your family history. A real person from Dr Vani's team replies on WhatsApp, usually within minutes during clinic hours (Mon to Sat, 9am to 5pm. Sunday closed.).
Chat on WhatsAppCall +91 89399 94244
Sex selection is prohibited in India under the PCPNDT Act, 1994 and the ART Act, 2021.