A genotype-phenotype correlation analysis based on a literature review shows that combination of two truncating variants in TMEM67 gene is more common in lethal MKS than milder JBS (Iannicelli et al., 2010; Szymanska et al., 2012; Bachmann-Gagescu et al., 2015; Vilboux et al., 2017), which suggests that severity of variant changes disease outcomes. Here, TMEM67 is linked to Meckel syndrome, type 1.