For instance, while usually complete loss of function of RPGRIP1L or MKS1 causes a lethal MKS phenotype, rare biallelic truncating variants in these genes have been reported in living patients with JS (Brancati et al., 2008; Brunetti‐Pierri et al., 2021; Romani et al., 2014a; Romani et al., 2014b). Here, MKS1 is linked to Meckel syndrome, type 1.