Here, we aimed at confirming the role and the prevalence of SIX2 mutations in a large cohort of 125 individuals with various congenital abnormalities of kidneys and urinary tract.
Moreover, whereas Six1 <sup>-/-</sup> mice exhibited partial transformation of maxillary zygomatic bone into a mandibular condyle-like structure, Six1 <sup>-/-</sup>Six2 <sup>+/-</sup> mice exhibit significantly increased penetrance of the maxillary malformation.
We suggest SIX2 haploinsufficiency as a potential congenital factor could be attributed to developmental malformation of the middle ear ossicles and upper eyelid.