What happens inside the lab
Three to five weeks of chemistry, scanning, and quality control — here is what your sample is doing.
Accessioning
Your card is checked in, its barcode matched against your registration, and the spots inspected for volume and quality. This is the step that fails fastest if a card was under-filled or sealed damp — and the step where a replacement gets triggered early rather than three weeks in.
Extraction and bisulfite conversion
DNA is extracted from the dried spot, then treated with sodium bisulfite. This is the clever part: the treatment converts unmethylated cytosines into uracil while leaving methylated ones untouched.
The chemistry turns an invisible difference into a readable one. After conversion, a methylated site and an unmethylated site are literally different letters, and a sequencer or array can tell them apart.
Array scanning
The converted DNA is hybridised to a methylation array and scanned. Hundreds of thousands of positions across your genome are read in a single pass, each one reported as the proportion of your cells carrying that mark.
Quality control and clock computation
Before any number reaches you, the run is checked: control probes, detection rates, predicted versus reported sex, and sample-level outliers. Anything that fails is rerun rather than reported.
Only then are the clocks computed and your report generated. It is a slow process because most of it is chemistry and verification, not computation.