Novel de novo PCDH19 mutations in three unrelated females with epilepsy female restricted mental retardation syndrome.

Epilepsy and Mental Retardation Limited to Females (EFMR) [OMIM 300088] was first described in 1971 [Juberg and Hellman, 1971] in 15 related females with early onset grand mal seizures and mental retardation. Although EFMR demonstrates X-linked inheritance, it follows an unusual pattern by sparing transmitting males and affecting only heterozygous females. In 2008, mutations within the protocadherin 19 (PCDH19) gene were implicated as causative of EFMR [Dibbens et al. (2008); Nat Genet 40:776-781]. The EFMR phenotype is typically characterized by seizure onset in infancy and mild to severe intellectual impairment. Several individuals with EFMR have also been described as having autistic features. We describe three unrelated female individuals, ranging in age from 3 to 19 years, with de novo novel PCDH19 mutations. All three individuals have seizure onset in infancy and require the use of multiple antiepileptic drugs. They also have varying degrees of intellectual impairment along with the presence of autistic features. Although most individuals with EFMR described to date demonstrate this unusual familial X-linked inheritance, our three unrelated females with de novo mutations highlight the importance of testing PCDH19 in females with early onset epilepsy, intellectual impairment, and autistic features, regardless of family history.