Holoprosencephaly-postaxial polydactyly syndrome associates, in chromosomally normal neonates, holoprosencephaly, severe facial dysmorphism, postaxial polydactyly and other congenital abnormalities, suggestive of trisomy 13 (see this term).

Distance between the commissures of the mouth more than 2 SD below the mean. Alternatively, an apparently decreased width of the oral aperture (subjective).