Trisomy 18 Edwards Syndrome

Trisomy 18, initially identified in 1960,83 causes serious birth defects including a low birth weight; microcephaly; a characteristic facies with fawnlike ears, micrognathia, high arched palate, a narrow bifrontal diameter, and prominent occiput; hypertonicity; poor muscle development; hand flexion with overlapping of second and fifth fingers; and limited hip abduction (Fig. 3-10). Rocker-bottom feet, webbing of toes, and dorsiflexion of a short great toe are common. Renal anomalies including horseshoe kidney and collecting duct malformations, cardiac malformations, pyloric stenosis, eventration of the diaphragm, and Meckel diver-ticulum may occur. Apnea and failure to thrive are serious complications. The majority (90%) die before 1 year of age.

The most common ophthalmic anomalies include epican-thus, hypertelorism, and hypoplastic supraorbital ridges. Less frequently, corneal opacities, congenital glaucoma, cataract, microcornea, retinal depigmentation, colobomatous microph-thalmia, and cyclopia are evident (Fig. 3-10).156,262,312

Pathological findings include corneal opacities with lamellar disorganization and fibrosis of the stroma, anomalies of the

Caracteristicas Sindrome Edwards
FIGURE 3-10. Trisomy 18. The corneas are enlarged as a result of glaucoma. (Courtesy of Eric A. Wulfsberg, M.D.)

ciliary processes, breaks in the iris sphincter, posterior subcapsular cataract, and retinal pigment epithelial alterations.133294

Trisomy 18 is caused by the presence of an extra chromosome 18; rarely, an unbalanced translocation may cause the syndrome. The incidence increases with maternal age.

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