SIX2 and frontonasal dysplasia: While SIX2 missense variants have been associated with renal hypodysplasia, SIX2 haploinsufficiency has not been linked to a renal phenotype so far but to frontonasal dysplasia, ptosis, and hearing loss (Weber et al., 2008; Guan et al., 2016; Henn et al., 2018).