0118The molecule
Nucleotide
A nucleotide is one building block of DNA: a phosphate group, a sugar, and a nitrogenous base, joined together.
Why it matters — Chain millions of them end to end and you have a strand of DNA.
Supporting section
A 18-chapter journey, controlled entirely by scrolling. It starts inside a single molecule and ends at the question BharatGenome exists to answer. No biology background is assumed.
0118The molecule
A nucleotide is one building block of DNA: a phosphate group, a sugar, and a nitrogenous base, joined together.
Why it matters — Chain millions of them end to end and you have a strand of DNA.
0218The molecule
DNA uses four bases — adenine, thymine, guanine and cytosine. Adenine always pairs with thymine, and guanine always pairs with cytosine.
A–T · G–C
Why it matters — Because the pairing is fixed, one strand always predicts the other.
0318The molecule
DNA is a long molecule of two complementary strands of nucleotides, wound around each other into a double helix.
Why it matters — Every idea in the rest of this page is about differences in this one molecule.
0418Reading it
The sequence is the order in which the bases occur along a strand.
A T G C A A T G — illustrative sequence
Why it matters — The information is carried by the order, not by the letters themselves.
0518Reading it
A gene is a region of DNA that carries the information for a functional product, such as a protein or a functional RNA.
Why it matters — A gene is a stretch of the molecule, not a separate object floating beside it. Most of the genome lies outside genes.
0618Packaging
A chromosome is DNA wound around proteins and packaged into one organised structure.
Why it matters — Packaging is how roughly two metres of DNA fits inside a single cell nucleus.
0718Packaging
A genome is the complete set of genetic material in an organism — every chromosome, every gene, and everything in between.
Why it matters — Nucleotide, DNA, gene, chromosome, genome: one thing nested inside the next.
0818Packaging
A human genome is about three billion base pairs, held in 23 chromosome pairs, in almost every cell of the body.
Why it matters — Everybody carries one. No two are identical.
0918Difference
Genetic variation is the difference in DNA sequence between individuals.
Why it matters — Any two people are more than 99% identical in sequence. Variation is the remainder.
1018Difference
A variant is a position where one sequence differs from the sequence it is being compared against.
A T G C · A A T G A T G C · G A T G
Why it matters — A variant is not automatically harmful, protective, or meaningful. Most have no known effect at all.
1118Difference
An allele is one of the alternative versions of a sequence found at a given position.
Why it matters — If some people carry A at a position and others carry G, then A and G are its two alleles.
1218Populations
A population is a group of individuals considered together when studying genetic variation.
Why it matters — A population is defined by the study that measures it, not by how anyone looks. It is a useful grouping with real limits.
1318Populations
Allele frequency is how common one allele is within a population.
A 60% · G 40% — illustrative
Why it matters — It is always a statement about a specific group of people. Ask a different group and the number can change.
1418Populations
The same position can carry very different allele frequencies in different populations.
same position · three populations · illustrative
Why it matters — A variant that is uncommon in one population may be common in another — which is why the population a number came from matters.
1518Representation
A reference genome is an agreed representative sequence, used as a shared standard for describing and comparing genomes.
Why it matters — It is a map everyone agrees on. It is not the genome of an average human, and not a 'correct' genome.
1618Representation
Genomic representation is how well the diversity of real human populations is actually captured by the reference resources research depends on.
Why it matters — Reference resources have historically not represented all populations equally. Where that coverage is thin, population-specific variation can be missed, underrepresented, or harder to interpret.
1718BharatGenome
India holds a large share of humanity and many long-separated populations, producing genetic structure that widely used reference resources cover thinly.
Why it matters — 'Indian' is itself a simplification — it is many populations, with deep structure between them.
1818BharatGenome
BharatGenome exists so that genomic evidence for Indian populations can be read alongside global evidence, with the provenance and the limits of each number stated.
Why it matters — The problem is not that India needs a genome. It is that genomic interpretation should account for populations that reference resources have historically underrepresented.
What you just travelled through
Every level of that journey is contained in the one above it. This is the relationship worth keeping.
A gene is a region of DNA. A chromosome is that DNA packaged. A genome is the complete set. Nothing on this list is a separate object from the one above it.
That is the whole idea. The next step is to run it on a real gene or variant.
That last step is what Explore produces for a gene, variant, or rsID you care about.
Reference
The journey introduces the 18 ideas you need to read a comparison. These 23 entries are the rest of the vocabulary — the terms that appear in a result, in the literature, and in the methodology.
The vocabulary for talking about what is inside a cell.
DNA is a long chemical instruction manual carried inside almost every cell in your body. It holds the information a cell needs to build and run itself.
a very long book written in a four-letter alphabet, copied into every room of a house.
Everything BharatGenome compares is ultimately a difference in this text between groups of people.
DNA is written with only four letters — A, C, G and T, called bases. Their order along the strand is what carries the information.
an alphabet with four letters instead of twenty-six. Meaning comes from the order, not the number of letters.
When we say a population carries 'A' or 'G' at a position, these are the letters we mean.
DNA is not one loose strand. It is packaged into 46 bundles called chromosomes — 23 inherited from each parent.
chapters of the book, each bound separately so the whole thing stays organised.
A variant is located by chromosome and position — that coordinate is how two datasets know they are talking about the same spot.
A gene is a stretch of DNA with a job — usually the recipe for one protein. Humans have roughly 20,000 of them.
one recipe inside the cookbook. The whole book is not a recipe; a specific passage is.
Searching a gene symbol in Explore is usually how a researcher starts, because genes are the unit most research is organised around.
A genome is the complete set of DNA in one organism — all the chromosomes, all the genes, and everything in between.
the entire cookbook, not just one recipe.
'Genomic representation' is about whose whole genomes were read to build the datasets everyone else relies on.
Any two people are over 99% identical in DNA. This section is about the rest.
A variant is a spot where people's DNA differs — one letter swapped, or a short stretch inserted or deleted.
a typo that appears in some printings of a book but not others. Most typos change nothing; a few change the meaning.
Variants are the objects BharatGenome compares. How common a variant is can differ a lot between populations.
A SNP (single nucleotide polymorphism) is the most common kind of variant: exactly one letter differs, and that difference is reasonably common in at least some population.
a single-character typo, as opposed to a whole missing paragraph.
Most frequency comparisons — and most of the research that depends on them — are about SNPs.
An allele is one of the alternative versions found at a variant position. If some people have A there and others have G, then A and G are the two alleles.
the two spellings of a word that both appear in print — 'colour' and 'color'. Each spelling is an allele.
The Indian-vs-global comparison is literally a comparison of how common each allele is.
In genomics, a population is a group of people studied together, usually because of shared ancestry or geography. A frequency is always a statement about a specific population.
a survey sample. 'What do people think?' is meaningless until you say which people were asked.
India is not one population — it is many, with deep structure. Even 'Indian' is a simplification, and BharatGenome says so on every result.
Allele frequency is how common one allele is in a group of people, written as a percentage. If 60% of the copies counted in a group are A and 40% are G, those are the allele frequencies.
asking a crowd which spelling they use and reporting the split. The answer describes that crowd — ask a different crowd and you may get a different split.
This is the single number at the heart of BharatGenome. The whole product exists because it is not the same everywhere.
An rsID (like rs1801133) is a stable public identifier for a known variant, so different databases can refer to the same position without ambiguity.
an ISBN for a book. Different shops, different catalogues, same number.
It is the cleanest way to ask two different datasets about exactly the same variant — which is what a comparison requires.
Try it: pick a letter
This is a short stretch of DNA. Choose any base to see what a change at that position would mean.
Nothing changed yet — every person's copy reads the same here.
Where the numbers in genomics actually come from — and whom they describe.
A reference genome is one agreed-upon sequence used as a shared coordinate system, so everyone can describe positions the same way. It is a map, not an ideal or 'correct' genome.
street numbering for a city. Useful because everyone agrees on it, not because house number 1 is the best house.
Coordinates come from the reference. It is a standard for locating things, and should not be read as what a genome 'should' look like.
A reference panel is a collection of already-sequenced genomes used as a lookup table to fill in or interpret new data.
a phrasebook compiled from certain speakers. It works well for dialects it covers and poorly for ones it does not.
If a panel contains few Indian genomes, the results it produces for Indian samples are weaker — a direct, practical consequence of representation.
Imputation fills in variants that were not directly measured, by inferring them from nearby measured variants using a reference panel.
autocomplete. It guesses the rest of the word from the letters typed — and it guesses much better in a language it was trained on.
Imputation quality depends on the panel matching the person. Under-represented populations get less accurate imputation.
Nearby variants tend to be inherited together, so knowing one often tells you about another. That statistical tendency is called linkage disequilibrium, or LD.
words that usually travel together in a phrase. Hear the first and you can often guess the second — but which words pair up differs by dialect.
LD patterns differ between populations, so a result anchored to one population's LD structure may not point at the same thing in another.
The methods that inherit whatever population the underlying data came from.
A genome-wide association study scans many variants across many people to find positions statistically associated with a trait or condition.
comparing two large groups' shopping lists to spot items that show up far more often in one.
GWAS results reflect the cohort that was studied. If Indian cohorts are absent, the associations found may not be the ones that matter here.
A polygenic risk score adds up the small effects of many variants into a single number summarising a person's genetic predisposition relative to a studied group.
a credit score built from many small signals — and calibrated on one particular set of customers.
PRS are known to lose accuracy when applied to populations unlike the one they were derived from. That loss is the representation problem in its most visible form.
Pharmacogenomics studies how genetic differences affect the way people process medicines — how fast a drug is broken down, for example.
different people metabolising caffeine at different rates. Same cup, different effect.
The frequency of relevant variants differs between populations, so population-specific frequency data has direct research value here. BharatGenome reports frequencies only; it gives no clinical or dosing guidance.
Everything above, pointed at the question BharatGenome exists to address.
Population representation is about whose genomes are actually in the datasets that research depends on. A well-represented population is one whose diversity is genuinely captured.
a national survey that mostly polled one region. The findings are real, but they describe that region best.
This is the core problem statement. India's share of global genomic reference data is far smaller than its share of human genetic diversity.
Transferability is whether a finding established in one population still holds in another. Many genomic findings transfer only partially.
a recipe developed at sea level. It still works in the mountains, but not without adjustment.
BharatGenome's comparison is a transferability check: does the global number describe the Indian population, or not?
Because allele frequencies differ, LD patterns differ, and which variants were even measured differs. A method tuned on one population inherits all three assumptions.
a spell-checker trained on one dialect. It is not broken — it is simply calibrated for someone else.
It explains why this is a methodological issue with measurable consequences, not a matter of fairness alone.
India holds a large share of humanity and a distinctive, highly structured pattern of genetic diversity shaped by its population history. That diversity is thinly covered in widely used reference resources.
a library with one wall of shelves left largely unfilled — you cannot tell what you are missing until you look.
It is the reason BharatGenome makes Indian evidence the default side of every comparison rather than an optional filter.
BharatGenome puts Indian and global evidence side by side for the same query, explains the difference in plain language, links supporting literature, and states the provenance, confidence and limits of every figure. When a provider has no data, it says so instead of estimating.
a second opinion printed next to the first, with both doctors' credentials attached.
Making the gap visible and quantified is what turns a known problem into something a researcher can act on.
A note on scope