A female patient with frontonasal dysplasia sequence and frontonasal encephalocele

Subtypes of frontonasal dysplasia are useful in determining clinical prognosis

Frontonasal dysplasia [FND; OMIM 136760] results from abnormal morphogenesis of the frontonasal process with disruption of the formation of the facial midline. Craniofacial anomalies in FND include anterior cranium bifidum, ocular hypertelorism, orofacial clefting and notching or clefting of the alae nasi. The majority of FND cases are sporadic and discordance has been demonstrated in monozygotic twin pairs, arguing against a strong inherited component in pathogenesis. However, pedigrees with Mendelian inheritance and non-recurrent chromosome aberrations in FND patients demonstrate that gene mutations or cytogenetic imbalance can also be important in the etiology of this phenotype. We classified 101 reported cases of FND from the medical literature and three new cases into seven separate FND phenotypic subtypes in addition to isolated FND. Our aim was to evaluate FND patients for distinct phenotypes within the FND spectrum and to determine the evidence for a genetic etiology in each of the different subtypes. Our analysis showed significant differences in the severity of the accompanying malformations and the rates of learning disabilities in the FND subtypes, although the small patient numbers and method of patient ascertainment may have influenced the data. The results suggest that cases with FND should be evaluated for additional anomalies, as these may help to determine prognosis.

A mild case of frontonasal dysplasia: the rhinologic perspective

Frontonasal dysplasia (FND) is a congenital malformation characterized by hypertelorism, broad nasion with a midline cleft in the bony dorsum, midline defect of the frontal bone, absence of the nasal tip, and deformities in the nasal alar region. The clinician should be aware of the mild forms of FND. We presented absence of crista galli in a mild case of FND. Computed tomography scanning should assess the facial bones, nose, and paranasal structures. If a surgical correction is planned, this complete work-up prevents unexpected complications and complements the evaluation of paranasal deformities.