PM20D1 and infection: However, while considering potential causal mutations, we would like to raise attention to two missense variants that pointed at genes with functions that may potentially influence the risk of a severe infection outcome: (i) a variant located in an exon of the peptidase M20 domain containing 1 gene (PM20D1) and (ii) a variant located in an exon of the low-density lipoprotein receptor-related protein 4 gene (LRP4) (Fig 4, Table 1).