title: Monozygotic twins discordant for external hydrocephalus.
abstract: External hydrocephalus (EH) is a transient, developmental condition in infancy characterized by macrocephaly and prominence of the subarachnoid spaces. The cause is unknown, but many patients have a family history consistent with autosomal dominant inheritance. This report describes a pair of monozygotic twins, only one of whom--the recipient of a twin-twin transfusion--has EH. Whatever the genotype of the twins, their discordant phenotypes suggest that the disproportionate calvarial growth that characterizes EH is set in motion--or not--during a limited, critical temporal window in fetal development.
authors.affiliation: Section of Neurosurgery, St. Christopher's Hospital for Children, and Department of Neurological Surgery, MCP Hahnemann University, Philadelphia, Pa 19134-1095, USA. joseph.piatt@tenethealth.com
authors.forename: J H
authors.initials: JH
authors.lastname: Piatt
mesh_terms: D002552:Cerebral Ventricles / Q000473:pathology; D002675:Child, Preschool; D004200:Diseases in Twins / Q000235:genetics*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D006849:Hydrocephalus / Q000175:diagnosis / Q000235:genetics* / Q000601:surgery; D009460:Neurologic Examination; D010641:Phenotype; D012886:Skull / Q000473:pathology; D014430:Twins, Monozygotic / Q000235:genetics