One of the most common questions parents ask after an autism diagnosis is: Why did this happen? Was it something we did? Is it genetic? Could it happen to our next child? Genetic testing can help answer some of these questions — but knowing which test to order, what it can realistically find, and how to interpret results requires careful guidance.
This article explains what genetic testing for autism involves in the Indian context, what it can and cannot tell you, and how a genetic counselor fits into this process.
Is Autism Genetic?
Autism Spectrum Disorder (ASD) is one of the most heritable neurodevelopmental conditions we know of. Twin studies consistently show heritability of 80–90% — meaning genetics explains the large majority of why autism occurs. But this does not mean autism is caused by a single gene or follows a simple inheritance pattern.
Autism genetics is complex:
- In some children, autism is caused by a single identifiable genetic change — a chromosomal deletion, duplication, or a mutation in one gene. These are called monogenic or syndromic causes.
- In other children, autism arises from the interaction of many common genetic variants, each contributing a small effect — called polygenic autism. No single test can identify this.
- Environmental factors (prenatal exposures, complications, infections) interact with genetic predispositions and account for a minority of cases.
Current genetic testing finds a specific, identifiable cause in approximately 25–30% of children with ASD when chromosomal microarray and whole exome sequencing are both used. The remaining 70–75% are not explained by today's technology — but the science is advancing rapidly.
Why Get Genetic Testing for a Child with Autism?
Some parents ask: If testing won't change my child's therapy, why bother? This is a fair question. The reasons for testing go well beyond changing the immediate treatment plan:
- A diagnosis explains associated medical features. Many genetic conditions that cause autism also cause cardiac defects, epilepsy, kidney anomalies, or immune problems. Knowing the genetic cause tells doctors what to monitor and when.
- It stops the diagnostic odyssey. Families who spend years wondering why often describe a specific genetic diagnosis as deeply relieving — even when the news is difficult.
- It connects families to resources. Condition-specific communities, clinical trials, and research registries are organised around genetic diagnoses. A family with a 16p11.2 deletion, for example, has access to a global network of families and researchers studying exactly that condition.
- It informs family planning. The recurrence risk for a sibling depends entirely on the genetic cause found (or not found). Without testing, families must use uncertain population-based risk figures.
- In a small number of cases, it directly affects treatment. Fragile X syndrome, tuberous sclerosis complex, PTEN mutations, and PKU (phenylketonuria) all have condition-specific management and in some cases, targeted treatments.
Which Genetic Tests Are Available for Autism in India?
Tests should be done in a logical sequence — not all at once. Each test has different strengths, costs, and appropriate indications. A genetic counselor helps select the right test for your child's specific presentation.
Standard karyotype is NOT sufficient for autism evaluation. A normal karyotype only rules out large chromosomal abnormalities visible under a microscope. It misses the smaller deletions and duplications (CNVs) and all single-gene mutations that cause the majority of identifiable autism cases. If your child has had only a karyotype, further testing is recommended.
Known Genetic Causes of Autism — What Testing Can Find
Hundreds of genes and chromosomal regions have been associated with ASD. The following represent the most clinically established:
| Condition / Gene Region | Key Features Beyond ASD | Test That Finds It |
|---|---|---|
| Fragile X Syndrome (FMR1) | Intellectual disability, large ears, hyperactivity; family history of cognitive issues; primarily affects boys | Dedicated FMR1 test |
| 22q11.2 Deletion (DiGeorge/VCFS) | Congenital heart defects, cleft palate, immune deficiency, characteristic facial features | CMA |
| 16p11.2 Deletion / Duplication | Macrocephaly (deletion) or microcephaly (duplication), language delay, variable expressivity | CMA |
| 15q11-q13 (Angelman / Prader-Willi / Duplication) | Angelman: severe ID, seizures, happy demeanour; PWS: hypotonia, obesity; duplication: autism | CMA (+ methylation for AS/PWS) |
| Tuberous Sclerosis (TSC1 / TSC2) | Skin findings (ash-leaf spots, angiofibromas), seizures, brain tubers, kidney angiomyolipomas | WES / gene panel |
| PTEN Macrocephaly Syndrome | Head circumference >98th percentile, autism, increased cancer risk in adulthood | WES / PTEN gene test |
| SHANK3 / Phelan-McDermid Syndrome (22q13.3) | Severe language delay, hypotonia, absent or minimal speech, autism | CMA / WES |
| ADNP Syndrome | Intellectual disability, behavioural features, de novo mutation; often sporadic | WES (trio) |
| CHD8 Mutation | Macrocephaly, GI problems (constipation), tall stature, de novo mutation | WES (trio) |
| Rett Syndrome (MECP2) | Primarily girls; regression after normal early development; hand-wringing, breathing irregularities | WES / MECP2 gene test |
Understanding Your Child's Genetic Test Result
Recurrence Risk — What Are the Chances for a Second Child?
One of the most pressing questions for parents of a child with autism is whether a future child faces the same risk. The answer depends almost entirely on what genetic testing finds:
- De novo mutation identified (a new mutation in the child that neither parent carries): recurrence risk is very low — approximately 1–2%, because the mutation arose spontaneously and is not in the parents' sperm or egg cells. Note: a small percentage of de novo cases are due to germline mosaicism in a parent, slightly raising the risk above the baseline.
- Autosomal dominant inherited mutation: each parent who carries the mutation has a 50% chance of passing it to each child. If neither parent is affected, testing the parents is critical to assess this.
- X-linked cause (such as Fragile X): risk depends on whether the mother is a carrier. Carrier mothers have a 50% chance of passing it to each son (who would be affected) and each daughter (who would be a carrier or mildly affected).
- No genetic cause found (negative result): the empirical recurrence risk based on population studies is approximately 10–20% for a full sibling — significantly higher than the general population risk of 1–2%.
If you are planning another pregnancy and your child has ASD with a known genetic cause, preimplantation genetic testing (PGT-M) via IVF is an option to consider — it allows embryos to be tested before transfer and only unaffected embryos to be used. A genetic counselor can advise whether this is appropriate for your specific situation.
Getting Genetic Testing for Autism in India
Access to ASD genetic testing has improved considerably in India over the past few years. NABL-accredited laboratories in Mumbai, Hyderabad, Bengaluru, and Chennai now offer chromosomal microarray and whole exome sequencing, with turnaround times of 3–10 weeks. Results from these labs can be interpreted in a genetic counseling session regardless of where in India the family is located — in-person in Ahmedabad, or via online genetic counseling.
The Challenge: Who Refers for Genetic Testing?
In India, most autism diagnoses are made by developmental paediatricians, child psychiatrists, or child neurologists — and referral to genetics is not yet routine practice. Many families receive an autism diagnosis without ever being told that genetic testing is available or recommended. As a result, families often seek genetic counseling independently, months or years after diagnosis.
This is entirely appropriate — it is never too late to pursue genetic testing for a child with autism, regardless of age at the time of referral.
Interpreting Results Without a Genetic Counselor
CMA and WES reports are technically complex — they list variants with classifications and inheritance information that require specialist interpretation. Well-meaning but non-specialist interpretation of these reports has led to parents being told a VUS is "the cause" of their child's autism, or conversely, that a positive result requires no further action. All genetic test results for autism should be reviewed with a genetic counselor.
Frequently Asked Questions
Yes — current international guidelines recommend genetic testing for all children diagnosed with autism spectrum disorder (ASD), regardless of severity. The most important first-line test is chromosomal microarray (CMA). Whole exome sequencing (WES) is recommended if CMA is negative and the child has additional features such as intellectual disability, seizures, or dysmorphic features. A genetic counselor can review your child's specific presentation and recommend the most appropriate test, avoiding unnecessary or out-of-sequence testing.
Sometimes yes, sometimes no — but the search for a genetic cause is valuable regardless. A specific genetic diagnosis can: (1) explain associated medical features and guide surveillance (e.g., cardiac monitoring in 22q11.2 deletion, epilepsy monitoring in tuberous sclerosis); (2) connect you to condition-specific research and support communities; (3) clarify recurrence risk for family planning; and (4) in some cases, directly inform therapy. For conditions including Fragile X syndrome, tuberous sclerosis, and PTEN mutations, specific management protocols exist.
A negative result doesn't mean there is no genetic cause — it means the current test didn't find one. Roughly 70–75% of autism cases remain genetically unexplained even after comprehensive testing, because our understanding of autism genetics is still evolving. New genes associated with ASD are identified every year. Some families choose to retest in 2–3 years as technology improves. A negative result is still useful — it makes certain inherited causes less likely, which matters for assessing sibling risk.
The recurrence risk depends on whether a genetic cause was found. If a de novo (new) mutation was identified in your child that neither parent carries, recurrence risk is low (approximately 1–2%). If an inherited gene mutation is found, the risk depends on that gene's inheritance pattern. If no genetic cause is found, the empirical recurrence risk for a sibling is approximately 10–20% — higher than the general population risk of 1–2%. A genetic counselor calculates the specific risk for your family after reviewing test results.
Fragile X syndrome is the most common single-gene cause of intellectual disability and autism, caused by a CGG repeat expansion in the FMR1 gene on the X chromosome. About 30% of boys with Fragile X meet criteria for autism. It can be carried silently through generations — a grandmother may pass the premutation to her daughters, whose sons are then at risk of full Fragile X. A dedicated FMR1 test is required to diagnose it, as standard CMA and karyotype do not detect it. It is an important part of every autism genetic evaluation.
A genetic counseling session at MyGeneScreen Clinic is ₹1,500 — this includes review of your child's history, recommendation of appropriate tests, and result interpretation. The tests themselves are through diagnostic labs: CMA typically costs ₹12,000–₹25,000; Fragile X testing is ₹3,000–₹6,000; Trio WES costs ₹25,000–₹45,000. Not all children need all tests — a genetic counselor ensures you do the right test in the right order, which saves money and avoids confusing results.
Autism Genetic Counseling in Ahmedabad & Online
Has your child been diagnosed with autism? Wondering whether genetic testing is right for your family, or struggling to make sense of a test result you already have? MyGeneScreen Clinic provides expert genetic counseling for autism — in person in Ahmedabad or online anywhere in India.
Book Autism Genetic Counseling — ₹1,500