To determine whether CRS was causally associated with the SIX1 mutation, we interrogated existing cohorts of genetically undiagnosed CRS investigated by either WES/WGS (n=628)6 7 or RNA sequencing (n=386).8 This highlighted four additional families carrying rare heterozygous SIX1 variants (families 2–5; figure 1B, table 1). Here, SIX1 is linked to congenital rubella syndrome.