Frontometaphyseal dysplasia

Frontometaphyseal dysplasia (FMD) is a rare skeletal disorder belonging to the group of otopalatodigital spectrum disorders. It is characterized by prominent supraorbital ridges (frontal bossing), which give the face a distinctive appearance, combined with abnormal modeling (metaphyseal dysplasia) of the long bones. The condition affects multiple body systems including the skeletal, craniofacial, auditory, and respiratory systems. Key craniofacial features include a prominent brow ridge, wide nasal bridge, small mandible (micrognathia), and dental anomalies. Skeletal manifestations include bowing of the long bones, joint contractures (particularly of the fingers and toes), scoliosis, and metaphyseal flaring. Conductive hearing loss is common due to abnormalities of the ossicles in the middle ear. Some patients may develop subglottic stenosis (narrowing of the airway below the vocal cords), which can be a serious and potentially life-threatening complication. Frontometaphyseal dysplasia is most commonly caused by gain-of-function mutations in the FLNA gene (filamin A), located on the X chromosome. A second form (FMD type 2) has been associated with mutations in the MAP3K7 gene, inherited in an autosomal dominant pattern. Males with FLNA-related FMD tend to be more severely affected than females, who may show milder or variable features. The condition is typically recognized in childhood based on the characteristic facial features and skeletal abnormalities, with radiographic findings confirming the diagnosis. There is currently no cure for frontometaphyseal dysplasia. Treatment is supportive and multidisciplinary, focusing on managing specific symptoms. This may include hearing aids for conductive hearing loss, orthopedic interventions for skeletal deformities and joint contractures, dental care, and surgical management of airway obstruction when subglottic stenosis is present. Regular monitoring by specialists in genetics, orthopedics, otolaryngology, and audiology is recommended to address complications as they arise.

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