Frontonasal dysplasia is a rare abnormality involving the forehead, nose, and eyes. Other names for this condition include median cleft syndrome, frontonasal syndrome and frontonasal dysostosis. It is noticed at birth although a few cases have been diagnosed antenatally. It can occur sporadically but autosomal dominant, autosomal recessive, and X-linked patterns have also been reported.
Frontonasal dysplasia (FND) is a congenital midfacial malformation involving the nose, eyes, and forehead . It is believed to be due to the defective migration of the neural crest cells during embryologic midline nasal development although the exact etiology for the malformation is unknown.
It is known to occur sporadically but autosomal dominant, autosomal recessive, and X-linked patterns have also been reported  . Recently there have been studies linking FND with autosomal recessive mutations in the homeobox aristaless-like genes ALX1, ALX3 , ALX4 .
The presentation of FND is variable. To be described as FND the condition should include two or more of the following manifestations: hypertelorism, skin covered gap between the forehead bones (anterior cranium bifidum occultum), midline cleft involving the nose, palate and upper lip, broad base of the nose, clefting of the nasal ala, absence of the nasal tip, and widow's peak hairline along the frontal bone . Twice as many males have been reported to have hypertelorism as compared to females . Other abnormalities such as cataracts, colobomas, conductive hearing loss and corpus callosum agenesis can also be present.
Occasionally FND is associated with certain syndromes and other malformations like central nervous system abnormalities , tetralogy of Fallot, tibial aplasia, aural and cerebral anomalies. Individuals with FND usually have a normal intelligence quotient (IQ).
Several authors have published classifications of the highly variable midline facial cleft malformations   . DeMyer classified midline clefts into those with normal or excessive tissue (median cleft face syndrome) and those with deficient tissue or holoprosencephaly . Sedano termed the median cleft face syndrome as frontonasal dysplasia . Based on the genetic causes and clinical presentation, three types of FND have been described. In FND type 1 patients have nasal anomalies and ptosis. FND type 2 patients have hair loss with agenesis of the parietal bones, while males could have genital anomalies. FND type 3 individuals have ocular anomalies ranging from anophthalmia to microphthalmia, low set ears, and severe facial anomalies.
Although FND is typically diagnosed in the neonatal period, there have been reports of fetuses being diagnosed antenatally with the malformation  . When noticed at birth, the workup should include a detailed history and physical examination for identification of FND as well as associated respiratory problems, cardiac, neurological, and limb malformations. The presence of at least two or more of the characteristic morphological features of FND helps to clinch the diagnosis. Radiological tests like X-ray of the skull and computed tomography (CT scan) are important for confirming the diagnosis. CT scan is the gold standard for diagnosing FND .
Other tests like an electrocardiogram or a two-dimensional echocardiogram may be required to detect associated cardiac abnormalities.
Antenatal ultrasound is useful to detect hypertelorism and cranial malformations like encephalocele . There is a high incidence of a craniofacial malformation in the next sibling, so genetic counseling is important since genetic testing is as yet unavailable .