Molecular Genetics of Frontonasal Dysplasia


Frontonasal dysplasias (FND) are facial malformations characterised by the association of hypertelorism, midline facial cleft and nasal abnormalities. They are caused by an abnormal development of the frontonasal process. FND are clinically and molecularly heterogeneous. Molecular bases have been identified in seven FND entities so far: mutations in the X‐linked EFNB1 gene in craniofrontonasal syndrome; biallelic mutations in ALX3, ALX4 and ALX1 genes in frontonasal dysplasia type 1, 2 and 3, respectively; heterozygous recurrent mutation in ZSWIM6 gene in acromelic frontonasal dysostosis; heterozygous mutations in SPECC1L gene in Teebi syndrome and heterozygous mutations in TWIST1 gene in Sweeney–Cox syndrome. These genes are involved in different pathways. The molecular bases for other clinically described entities such as Pai or oculoauriculofrontonasal syndromes are still unknown despite international efforts to decipher their molecular basis using next‐generation sequencing technologies; almost all affected individuals are of sporadic occurrence. Most patients presenting with FND remain clinically unclassified. The rarity of these disorders and the multiple clinical overlaps account for their challenging and molecular clinical delineation.

Key Concepts

  • Frontonasal dysplasia consists of clinically and molecularly heterogeneous entities.
  • Molecular bases are known in a small subset of syndromic FND and still unknown in other clinically described disorders.
  • FND with known molecular bases are dominant, recessive, or X‐linked.
  • An accurate clinical diagnosis is essential for the patients and families management as well as for the identification of the causative molecular bases.
  • The genes involved in FND pathogenesis belong to different cellular pathways; most of their function is still poorly known.

Keywords: frontonasal dysplasia; craniofrontonasal syndrome; Teebi syndrome; acromelic frontonasal dysostosis; Pai syndrome; exome sequencing; genome sequencing

Figure 1. Facial phenotype associated with craniofrontonasal syndrome.
Figure 2. Facial phenotype associated with FND1 syndrome.
Figure 3. Facial phenotype associated with FND2 syndrome.
Figure 4. Facial phenotype associated with Teebi syndrome.
Figure 5. Facial phenotype associated with acromelic fontonasal dysostosis.
Figure 6. Facial phenotype associated with Pai syndrome.
Figure 7. Facial phenotype associated with oculoauriculofrontonasal syndrome.
Figure 8. Facial phenotype associated with Sakoda complex.
Figure 9. Facial phenotype associated with cerebro‐oculo‐nasal syndrome.


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Daphné, Lehalle, and Laurence, Faivre(Nov 2018) Molecular Genetics of Frontonasal Dysplasia. In: eLS. John Wiley & Sons Ltd, Chichester. [doi: 10.1002/9780470015902.a0027870]