DNA Microarray vs Whole Genome Sequencing: Which Test Do You Actually Need in India?

When you start researching DNA tests in India, you quickly run into two terms that sound very different but are often confused: SNP microarray genotyping (what consumer DNA kits use) and whole genome sequencing (what clinical labs offer). Marketing language doesn't always help — some companies describe high-density microarray as "genome analysis," which is technically accurate but sounds more impressive than it is.

This guide explains exactly what each method does, what it detects, what it misses, and who actually needs each — so you can make an informed decision rather than overpay for something you don't need or underpay for something that won't answer your question.

What SNP Microarray Genotyping Actually Does

Your genome contains approximately 3.2 billion base pairs. The vast majority are identical between all humans — the interesting variation happens at specific positions called single nucleotide polymorphisms (SNPs). SNPs are positions in the genome where individuals commonly differ — one person has an A, another has a G, for example.

A DNA microarray chip — the technology Helixline and most consumer DNA tests use — reads between 300,000 and 900,000 of these SNP positions in a single run. The positions are chosen deliberately: they are the SNPs that are most informative for ancestry analysis, common health risk variants, carrier status conditions, pharmacogenomics, and trait analysis. The result is highly actionable for these purposes because the selected SNPs overlap with decades of published genetic research.

When your swab arrives at the lab, here is what happens:

1. Cells from your cheek swab are lysed to release DNA.
2. Your DNA is hybridised onto the microarray chip — it binds to the complementary probe sequences on the chip at each of the ~700,000 positions being tested.
3. A laser scanner reads which allele (A, T, C, or G) is present at each position.
4. The resulting genotype data is matched against reference populations, published GWAS (genome-wide association study) data, and Helixline's India-specific reference panel to generate your ancestry and health reports.

What Whole Genome Sequencing (WGS) Actually Does

Whole genome sequencing reads every base pair in your genome — all 3.2 billion of them, typically multiple times (expressed as "coverage depth," e.g., 30× means each position was read an average of 30 times to reduce sequencing errors). The result is a massive dataset: a single 30× WGS run generates approximately 100 GB of raw data.

WGS detects things microarray genotyping cannot:

• Novel variants — rare mutations at positions not on any microarray chip, including de novo mutations not inherited from either parent
• Structural variants — large insertions, deletions, duplications, and inversions affecting thousands of base pairs
• Repeat expansions — the underlying cause of conditions like Huntington's disease and Fragile X syndrome
• Mosaic mutations — variants present in only some cells, which arise after conception

However, WGS also generates enormous amounts of data with uncertain significance. A typical 30× WGS run finds several million variants per person. Clinical interpretation requires a specialist geneticist to determine which (if any) are pathogenic — and most are not. This is why clinical WGS is a clinical tool, not a consumer product.

Side-by-Side Comparison

Feature	SNP Microarray (Helixline)	Clinical WGS (Hospital/Lab)
Positions read	~700,000 selected SNPs	~3.2 billion base pairs
What it finds	Common variants at known positions	Common + rare + novel + structural
Ancestry analysis	Yes — community-level South Asian resolution	Yes — but no better than microarray for this
Common health variants	Yes — BRCA1/2, APOE, CYP2C19, 40+ carrier conditions	Yes
Rare disease variants	Only if the variant is on the chip	Yes — comprehensive
Structural variants	Limited	Yes
Pharmacogenomics	Yes — 50+ drug-gene interactions	Yes — but often needs separate analysis
Turnaround	6–8 weeks	6–12 weeks (clinical)
Cost in India	₹6,999 – ₹17,999	₹40,000 – ₹1,50,000+
Clinical report	No — wellness/ancestry report	Yes — signed by clinical geneticist
Sample type	Cheek swab, at home	Blood draw, clinic visit required

Who Needs What: An Honest Guide

Choose SNP Microarray (Helixline) if you want:

• Community-level Indian ancestry results — which of India's 4,600+ endogamous communities your ancestors came from
• Haplogroup analysis — paternal Y-DNA lineage, maternal mtDNA lineage
• Health risk awareness for common conditions — BRCA1/2 for breast/ovarian cancer, APOE for Alzheimer's risk, cardiac risk variants
• Carrier screening before marriage or pregnancy — thalassemia, sickle cell, G6PD, SMA, and 40+ others
• Pharmacogenomics — how your body metabolises blood thinners, antidepressants, statins, and 50+ other medicines
• Nutrition and wellness traits — lactase persistence, Vitamin D metabolism, caffeine sensitivity
• NRI raw data upload — re-analyse your 23andMe or AncestryDNA data for community-level South Asian results

Choose Clinical WGS if you need:

• A rare or undiagnosed genetic condition that a clinical geneticist suspects and cannot resolve with targeted panel testing
• Full characterisation of a known pathogenic variant in your family that is not covered by standard carrier panels
• A formal clinical diagnostic report signed by a clinical geneticist (for medical records, insurance documentation, or specialist referrals)
• Research participation in a programme specifically requiring raw sequencing data

Why Microarray Is Sufficient for Ancestry — Even at Community Level

This is the question most worth addressing directly, because it seems counterintuitive. If WGS reads 3.2 billion positions vs microarray's 700,000, shouldn't WGS give dramatically better ancestry results?

Not in practice, for three reasons:

1. Ancestry algorithms use a subset of informative SNPs anyway. Reference population databases — the datasets that ancestry algorithms compare your DNA against — are built from specific SNP positions. Adding millions of additional positions from WGS doesn't help unless the reference database includes data at those positions. It doesn't. The world's largest ancestry reference databases (including Helixline's South Asian panel) are SNP-based.

2. The limiting factor is reference panel depth, not genotype density. The reason 23andMe gives "Broadly South Asian" results is not that they're using too few SNPs — they read 650,000+ positions. The problem is their reference panel doesn't include enough distinct South Asian community groups. Helixline's 200+ Indian regional reference populations resolve this. Adding WGS data wouldn't help; adding more reference populations does.

3. Community-level resolution comes from allele frequency differences, not rare variants. The differences between a Telugu Brahmin and a Tamil Nadar in their ancestry profile come from systematic differences in allele frequencies at known positions — exactly what microarray captures. WGS would not add resolution here.

The Helixline Kit Range Explained Honestly

Origins (₹6,999) — High-density SNP microarray. Ancestry breakdown to community level, Y-DNA and mtDNA haplogroups, population affinity analysis, raw genotype data download. Best for: ancestry curiosity, family history research, NRI diaspora wanting South Asian roots.

Origins+ (₹12,999) — Same ancestry as Origins, plus: 40+ carrier condition screening (thalassemia, sickle cell, G6PD, SMA, and others), common health risk variants (BRCA1/2, APOE, cardiac, diabetes), pharmacogenomics (50+ drug-gene interactions), 26 nutrition and wellness traits. Best for: anyone who wants both ancestry and actionable health information.

Genome Ultimate (₹17,999) — Highest-density SNP microarray chip available, covering a broader set of positions across the genome. Extends coverage of rare variant categories beyond what Origins and Origins+ chip covers, includes all Origins+ health and ancestry analysis, and produces the most comprehensive genotype dataset Helixline offers. Best for: users who want the most complete microarray dataset available, researchers wanting maximum SNP coverage, or those with a specific health concern requiring broader variant coverage. Note: this is still microarray, not whole genome sequencing.

Frequently Asked Questions