title: Fetus-fetus interaction--a model aetiology for anencephalus.
mesh_terms: D000757:Anencephaly / Q000453:epidemiology / Q000209:etiology* / Q000235:genetics*; D002490:Central Nervous System / Q000002:abnormalities; D004200:Diseases in Twins / Q000453:epidemiology / Q000235:genetics*; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D008962:Models, Theoretical; D012730:Sex Chromosomes; D012737:Sex Factors; D016135:Spinal Dysraphism / Q000209:etiology / Q000235:genetics