DISP1 and holoprosencephaly: However, human mutations in DISP1 are rarely diagnosed in HPE and have been reported in microforms with incomplete penetrance, at the level of the eyes showing hypotelorism and upslanting palpebral fissures (Roessler et al. 2009); other patients with compound heterozygous DISP1 mutations sometimes in combination with other HPE gene mutations, tend to only have hypotelorism in conjunction with lobar or microform HPE (Dubourg et al. 2016; Dupé et al. 2017).