Second-trimester molecular prenatal diagnosis of sporadic Apert syndrome following suspicious ultrasound findings.

Apert syndrome, an autosomal dominant disorder characterized by craniosynostosis, mid-facial malformations, symmetric bony syndactyly of hands and feet, and varying degrees of mental retardation, is most frequently caused by a de novo mutation. Two missense mutations in the fibroblast growth factor receptor 2 (FGFR2) gene have been found to account for the disorder in approximately 98% of affected patients. Seven cases of prenatal ultrasound diagnosis have been reported. Although one earlier diagnosis has been made in a familial case, sporadic cases have not been definitively diagnosed until the third trimester when craniosynostosis is usually detected. We report a second-trimester molecular diagnosis of a sporadic case, based on the ultrasound observation of fetal 'mitten hands' and craniosynostosis. We discuss the approach to such ultrasound features, given the current availability of molecular diagnosis for Apert syndrome.