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Craniofrontonasal dysplasia is a very rare X-linked disorder characterized by craniofacial abnormalities, grooved nails, intellectual deficit and various skeletal and soft tissue abnormalities. It occurs in less than 1/100,000 newborns. Detailed phenotypic analysis shows that females are more severely affected than males, a highly unusual characteristic for an X-linked disorder. Most of the males are mildly affected (with hypertelorism only). Females have frontonasal dysplasia (widely-spaced eyes or hypertelorism, and a flat and broad nose with a vertical groove on the top of the nose), coronal craniosynostosis with brachycephaly and frontal bossing. Skeletal deformities may include sloping shoulders with dysplastic clavicles, broad first toes, short first fingers, brachydactyly, clinodactyly, gaps between the first and second toes, long fingers and toes, syndactyly, polydactyly, camptodactyly, scoliosis and hyperextensible joints. The following facial abnormalities may be seen: microcephaly, facial asymmetry, downslanting palpebral fissures, dry, curly and frizzy hair, widows peak, low posterior hairline, webbed neck, highly arched palate, cleft lip and palate, malocclusion, abnormal auditory ossicles, and sensorineural deafness. Diaphragmatic hernia, pectus excavatum, shawl scrotum, hypospadias and agenesis of the corpus callosum occur occasionally. The syndrome can be caused by mutations in the EFNB-1 gene. This gene encodes ephrin-B1 and maps to Xq13.1. Another gene was mapped to Xp22, suggesting that the syndrome is genetically heterogeneous. The risk that an affected female will pass the disease on her daughter or son is 50%. An affected male will pass the disease on to all of his daughters but none of his sons. Multistage surgery is the general treatment plan for craniosynostosis. The synostotic sutures of the skull are released in the first year of life. The aim of this surgery is decompression of the brain and remodeling of the skull. As the child grows, skull remodeling may be required. Correction of the hypertelorism is delayed until the age of 5 when the child becomes aware of the deformity. |