Overall project workflow. (A) Significant stages of the project. (i) Variants underpinning antigen expression and those in antigen-encoding genes in sequence variation databases were collected for incorporation into an array design. (ii) An array was fabricated containing only donor-typing content, and the small test set of donor samples was used to detect manufacturing or technical errors. (iii) Based on the results of the previous step, algorithmic changes were made to improve variant and antigen calling and donor-typing content was integrated into the UK Biobank Axiom array design. (iv) The resulting UK Biobank version 2 array was fabricated and the large trial set of donor samples was used to assess antigen typing performance. (B) Typical array testing cycle.