Monozygotic twins with Apert syndrome.

Apert syndrome results almost exclusively from one of two point mutations (Ser252Trp or Pro253Arg) in fibroblast growth factor receptor 2. Most patients with Apert syndrome have this as an autosomal dominant abnormality. The majority of cases are sporadic, resulting from new mutations. Although there have been some descriptions of familial Apert syndrome, we could find only one previous description in the English literature about twinning in Apert syndrome. This report demonstrates monozygotic twins affected by Apert syndrome with both boys having the Ser252Trp mutation. Although the general constellation of clinical findings was characteristic for Apert syndrome, this case report is unique since the twins had different craniofacial and hand features. One of our twins had a metopic synostosis while Apert syndrome is often characterized by the large metopic suture that closes much later when compared to normal children.