Participants were genotyped using a custom content Affymetrix Axiom SNP array, consisting of 770 558 probes, enriched with markers related to immune dysfunction. The Ensembl Gene database, assembly hg19/GRCh37, was used to annotate genes within a 5 kb window of each variant. Genotyping was performed at Advanced BioMedical Laboratories, using standardized quality assurance procedures. As part of SNP-level QC, probes were removed if any of the following applied: probe was duplicate, multiallelic or nonautosomal, missingness >0.03, reproducibility less than 0.90, MAF <1% or deviation from the Hardy–Weinberg equilibrium with P < 1 × 10–6. At sample-level QC, participants were excluded if there was a sex mismatch, duplication or missingness. In order to capture potentially relevant TET2 phenotypes present in related individuals, participants were not excluded due to cryptic relatedness or outlying heterozygosity. After sample and SNP QC SNPs that mapped to TET2 as well as IDH1 and IDH2, (±5 kb) were selected for further analysis. These genes included TET2 as well as IDH1 and IDH2, two regulators of TET2 function [37 (link)].