Frontonasal Dysplasia

Frontonasal dysplasia is a rare disorder characterized by abnormal development of the head and face before birth.

Other names of Frontonasal Dysplasia #

• Median cleft face syndrome

• FND

• Frontorhiny

• Frontonasal malformation

Causes of Frontonasal Dysplasia #

Genetics #

• There is still some discussion on whether FND is sporadic or genetic.

• The majority of FND cases are sporadic.

• Yet, some studies describe families with multiple members with FND.

• Gene mutations are likely to play an important role in the cause.

• Unfortunately, the genetic cause for most types of FND remains undetermined.

Frontorhiny #

• The cause of frontorhiny is a mutation in the ALX3 gene.

• ALX3 is essential for normal facial development.

• Different mutations can occur in the ALX3 gene, but they all lead to the same effect: severe or complete loss of protein functionality.

• The ALX3 mutation never occurs in a person without frontorhiny.

Acromelic frontonasal dysostosis #

• Acromelic frontonasal dysostosis is caused by a heterozygous mutation in the ZSWIM6 gene.

• It is thought that acromelic frontonasal dysostosis occurs due to an abnormality in the Sonic Hedgehog (SSH) signaling pathway.

Symptoms of Frontonasal Dysplasia #

Nasal #

Mild anomalies to nostrils that are far apart and a broad nasal root, a notch or cleft of the nose and accessory nasal tags.

Ocular #

Narrowed eye slits, almond shaped eyes, epicanthal folds (extra eyelid tissue), epibulbar dermoids (benign tumors of the eye), upper eyelid colombas (full thickness upper eyelid defects), microphthalmos (one or two small eyes), congenital cataract and degeneration of the eye with retinal detachment.

Facial #

Telecanthus (an increased distance between the corners of the eye), a median cleft of the upper lip and/or palatum, and a V-shaped hairline.

Others #

Polydactyly (an excess of fingers or toes), syndactyly (fused fingers or toes), brachydactyly (short fingers and/or toes), clinodactyly (bending of the fifth fingers towards the fourth fingers), preauricular skin tags, an absent tragus, low set ears, deafness etc.

Diagnosis of Frontonasal Dysplasia #

• The main diagnostic tools for evaluating FND are X-rays and CT-scans of the skull.

• These tools could display any possible intracranial pathology in FND.

• For example, CT can be used to reveal widening of nasal bones.

• Diagnostics are mainly used before reconstructive surgery, for proper planning and preparation.

• Prenatally, various features of FND (such as hypertelorism) can be recognized using ultrasound techniques.

• However, only three cases of FND have been diagnosed based on a prenatal ultrasound.

Treatment of Frontonasal Dysplasia #

Facial bipartition with median faciotomy #

• To correct the rather prominent hypertelorism, wide nasal root and midline cleft in FND, a facial bipartition can be performed.

• This surgery is preferred to periorbital box-osteotomy because deformities are corrected with a better aesthetic result.

Rhinoplasty #

• Structural nasal deformities are corrected during or shortly after the facial bipartition surgery.

• In this procedure, bone grafts are used to reconstruct the nasal bridge.

• However, a second procedure is often needed after the development of the nose has been finalized (at the age of 14 years or even later).