Finally, a non-synonymous variant (rs1127354) leading to the removal of the second exon of ITPA (modified protein, Student’s test; psQTL < 2.8 × 10−12, R2 > 0.22, |SPIDEX’s Z| = 2.6) associates with increased susceptibility to hepatitis C virus infection and ribavirin-induced anaemia51. Here, ITPA is linked to hepatitis C virus infection.