ALX4 Gene

Frontonasal dysplasia is a condition that results from abnormal development of the head and face before birth. People with frontonasal dysplasia have at least two of the following features: widely spaced eyes (ocular hypertelorism); a broad nose; a slit (cleft) in one or both sides of the nose; no nasal tip; a central cleft involving the nose, upper lip, or roof of the mouth (palate); incomplete formation of the front of the skull with skin covering the head where bone should be (anterior cranium bifidum occultum); or a widow's peak hairline.

Other features of frontonasal dysplasia can include additional facial malformations, absence or malformation of the tissue that connects the left and right halves of the brain (the corpus callosum), and intellectual disability.

There are at least three types of frontonasal dysplasia that are distinguished by their genetic causes and their signs and symptoms. In addition to the features previously described, each type of frontonasal dysplasia is associated with other distinctive features. Individuals with frontonasal dysplasia type 1 typically have abnormalities of the nose, a long area between the nose and upper lip (philtrum), and droopy upper eyelids (ptosis). Individuals with frontonasal dysplasia type 2 can have hair loss (alopecia) and an enlarged opening in the two bones that make up much of the top and sides of the skull (enlarged parietal foramina). Males with this form of the condition often have genital abnormalities. Features of frontonasal dysplasia type 3 include eyes that are missing (anophthalmia) or very small (microphthalmia) and low-set ears that are rotated backward. Frontonasal dysplasia type 3 is typically associated with the most severe facial abnormalities, but the severity of the condition varies widely, even among individuals with the same type.

Life expectancy of affected individuals depends on the severity of the malformations and whether or not surgical intervention can improve associated health problems, such as breathing and feeding problems caused by the facial clefts.

Enlarged parietal foramina is an inherited condition of impaired skull development. It is characterized by enlarged openings (foramina) in the parietal bones, which are the two bones that form the top and sides of the skull. This condition is due to incomplete bone formation (ossification) within the parietal bones. The openings are symmetrical and circular in shape, ranging in size from a few millimeters to several centimeters wide. Parietal foramina are a normal feature of fetal development, but typically they close before the baby is born, usually by the fifth month of pregnancy. However, in people with this condition, the parietal foramina remain open throughout life.

The enlarged parietal foramina are soft to the touch due to the lack of bone at those areas of the skull. People with enlarged parietal foramina usually do not have any related health problems; however, scalp defects, seizures, and structural brain abnormalities have been noted in a small percentage of affected people. Pressure applied to the openings can lead to severe headaches, and individuals with this condition have an increased risk of brain damage or skull fractures if any trauma is experienced in the area of the openings.

There are two forms of enlarged parietal foramina, called type 1 and type 2, which differ in their genetic cause.

Enlarged parietal foramina is an inherited condition of impaired skull development. It is characterized by enlarged openings (foramina) in the parietal bones, which are the two bones that form the top and sides of the skull. This condition is due to incomplete bone formation (ossification) within the parietal bones. The openings are symmetrical and circular in shape, ranging in size from a few millimeters to several centimeters wide. Parietal foramina are a normal feature of fetal development, but typically they close before the baby is born, usually by the fifth month of pregnancy. However, in people with this condition, the parietal foramina remain open throughout life.

The enlarged parietal foramina are soft to the touch due to the lack of bone at those areas of the skull. People with enlarged parietal foramina usually do not have any related health problems; however, scalp defects, seizures, and structural brain abnormalities have been noted in a small percentage of affected people. Pressure applied to the openings can lead to severe headaches, and individuals with this condition have an increased risk of brain damage or skull fractures if any trauma is experienced in the area of the openings.

There are two forms of enlarged parietal foramina, called type 1 and type 2, which differ in their genetic cause.