Understanding DNA Test in India: Types, Accuracy, and When You Need One

Genetic testing has become an integral part of modern clinical practice in India. What was once restricted to rare disease diagnosis is now routinely influencing decisions in reproductive medicine, oncology, pediatrics, and internal medicine. As testing availability expands, the real challenge for clinicians is no longer access, but appropriate test selection, interpretation, and patient counselling.

This article provides a clinician-centric overview of DNA testing in India, focusing on clinical indications, test accuracy, and practical considerations for everyday practice.

Clinical Role of DNA Testing in Current Practice

A DNA test evaluates germline or somatic genetic variation to support diagnosis, risk stratification, prognosis, or therapeutic planning. Importantly, genetic testing should be viewed as an adjunct to clinical assessment, not a standalone diagnostic tool.

In Indian clinical settings, DNA testing is increasingly used to:

• Establish molecular diagnoses in undiagnosed or atypical presentations

• Identify inherited disease risk in asymptomatic individuals

• Guide reproductive decision-making

• Inform targeted cancer therapies

Appropriate test selection depends on phenotype, family history, and pre-test probability.

Categories of DNA Tests Commonly Used in India

Diagnostic Genetic Testing

This is typically considered when a patient presents with unexplained clinical features suggestive of a genetic etiology. Pediatric developmental delay, early-onset neurological disease, unexplained metabolic abnormalities, and syndromic presentations are common indications.

Targeted gene panels or exome-based approaches are often used depending on clinical complexity.

Carrier Screening Testing

Carrier screening is increasingly relevant in preconception and antenatal care. While traditionally limited to high-risk families, broader screening is now considered due to population-specific recessive disorders.

Clinicians should counsel patients that:

• A negative result reduces, but does not eliminate, risk

• Residual risk depends on test scope and gene coverage

Prenatal DNA Testing

Non-invasive prenatal testing (NIPT) has changed prenatal screening practices by offering high-sensitivity risk assessment for common aneuploidies using maternal blood.

From a clinical standpoint:

• NIPT is a screening, not diagnostic, test

• Positive results require confirmatory invasive testing

• Pre- and post-test counselling is essential to avoid misinterpretation

Newborn Screening

Early genetic or metabolic screening allows intervention before irreversible disease progression. While programs vary across India, clinicians should advocate for expanded newborn screening where feasible, especially for treatable conditions.

Oncology-Focused Genetic Testing

DNA testing in oncology serves two distinct purposes:

1. Germline testing for inherited cancer predisposition

2. Somatic testing to guide targeted therapy

Understanding the difference is critical, as germline findings have implications for family members and require appropriate counselling pathways.

Advanced Genomic Testing

Whole exome sequencing and clinical exome testing are typically reserved for cases where:

• Phenotype is unclear

• Prior investigations are inconclusive

• Multisystem involvement is present

While diagnostically powerful, these tests increase the likelihood of incidental or uncertain findings, reinforcing the need for expert interpretation.

Accuracy and Interpretation Considerations

From a laboratory perspective, modern DNA testing platforms used in India demonstrate high analytical accuracy. However, clinical validity and utility depend heavily on interpretation.

Key points clinicians should consider:

• Not all variants are pathogenic

• Variants of uncertain significance (VUS) should not guide irreversible clinical decisions

• Phenotype–genotype correlation remains critical

Collaboration with molecular pathologists and genetic counselors significantly improves result interpretation.

Indications for Referring a Patient for DNA Testing

DNA testing should be considered when results are likely to:

• Change diagnosis

• Influence management

• Alter surveillance or preventive strategies

• Inform reproductive decision-making

Testing without a clear clinical question increases the risk of ambiguous findings and patient anxiety.

Practical Aspects of DNA Testing in India

Sample collection is typically straightforward, involving blood or saliva. Turnaround time varies based on test complexity and laboratory workflow.

Cost considerations should be discussed transparently. Clinicians should emphasize clinical relevance over test breadth, particularly in resource-sensitive settings.

Ethical and Counselling Considerations

Genetic testing raises ethical issues that extend beyond the individual patient. Incidental findings, familial implications, and psychosocial impact must be addressed proactively.

Genetic counselling is not optional—it is a clinical necessity, particularly for predictive or prenatal testing.

Clinical Takeaway

A DNA test in India is most effective when:

• Clinically indicated

• Appropriately selected

• Correctly interpreted

• Accompanied by genetic counselling

For clinicians, the goal is not to order more genetic tests, but to order the right test for the right patient at the right time. Used judiciously, DNA testing strengthens diagnostic precision and supports personalized care without compromising ethical responsibility.