Frontonasal dysplasia is a rare midline anomaly characterized by malformations of the central portion of the face, especially of the forehead, the nose, and the philtrum. True ocular hypertelorism; broadening of the nasal root; a median facial cleft affecting the nose, upper lip, and palate; uni- or bilateral clefting of the alae nasi; lack of formation of the nasal tip; anterior cranium bifidum occultum; and a V-shaped prolongation of the hair onto the forehead are the main features. Frontonasal dysplasia may be associated with congenital heart abnormalities, in particular, tetralogy of Fallot, vertebral anomalies, agenesis of the cropus callosum, Dandy-Walker malformation, a short neck, short limbs, polydactyly of the hands and feet, and cryptochidism. These abnormalities can be present in any combination or severity although hypertelorism is a constant feature.
Most cases of frontonasal dysplasis are sporadic although a few familial cases have been described. Some reports are consistent with either autosomal or X-linked dominant inheritance. It has been proposed that search for a gene underlying frontonasal dysplasia should focus on 4 chromosome bands: 3q23, 3q27, 7q21, and 11q21. However, mutations in the ALX3 gene, mapped to the chromosomal region 1p13.3 has been reported to be causative in three families where the inheritance pattern was assumed to be autosomal recessive.