> For the complete documentation index, see [llms.txt](https://finngen.gitbook.io/documentation/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://finngen.gitbook.io/documentation/r4/methods/genotype-imputation.md).

# Genotypes

FinnGen individuals were [genotyped](/documentation/r4/methods/genotype-imputation/genotype-data.md) with Illumina and Affymetrix chip arrays (Illumina Inc., San Diego, and Thermo Fisher Scientific, Santa Clara, CA, USA).

Chip genotype data were [imputed](/documentation/r4/methods/genotype-imputation/genotype-imputation.md) using the population-specific[ SISu v3 imputation reference panel](/documentation/r4/methods/genotype-imputation/sisu-reference-panel.md) of 3,775 whole genomes.

Merged imputed genotype data is composed of 52 data sets that include samples from multiple cohorts.

* Total number of individuals: 183,694
* Total number of variants (merged set): 16,962,023
* Reference assembly: GRCh38/hg38