Oto-palato-digital syndrome

The most severe phenotypes of each syndrome occur only in males, with females generally having attenuated forms of the condition, although this does not apply to all individual cases.

[2] The conditions are characterised by skeletal abnormalities, cleft palate (a hole in the roof of the mouth), and hearing loss.

[2] In OPD2, the characteristic facial features are more severe and intellectual disability frequent; most OPD2 cases in males are stillborn or die during infancy.

[1][2] As an X-linked recessive disorder, both forms are generally more severe in males, who have one X chromosome, than females, who have two.

[1] Germline mosaicism for OPD1 has been reported, meaning that unaffected parents with an affected child have a slightly increased risk of bearing another.