Abstract
Frontonasal dysplasia (FND) is a rare complex genetic facial malformation, mostly characterized by affecting the face and head regions of the body. Craniofacial defects can have a severe impact, revealing different types of clinical phenotypes, which are broadly grouped as frontonasal dysplasias (FNDs). FNDs have been classified along with selected disorders on the genetic and molecular basis. FND is clinically diagnosed on the basis of at least two features including median facial cleft, broad nasal bridge, ocular hypertelorism, widened philtrum, median cleft upper lip, widow's peak frontal hairline and missing or underdeveloped nasal tip. The three types of FNDs are caused by the ALX genes (ALX1, ALX3, ALX4). Genes and pathways related to facial development are associated with direct or indirect expression of the FGF8, the SHH, and the BMP4. The present review provides a detail literature review on the FND phenotypes and mutation update of different genes involved that will help in proper classification, genetic counseling, and diagnosis of the affected families.

Key words: Frontonasal dysplasia, FND, ALX1, ALX3, ALX4.