Letter: Risks of malformed relatives.
D000757:Anencephaly / Q000175:diagnosis / Q000453:epidemiology / Q000235:genetics*; D005260:Female; D006801:Humans; D008297:Male; D011247:Pregnancy; D011296:Prenatal Diagnosis; D012306:Risk; D016135:Spinal Dysraphism / Q000175:diagnosis / Q000453:epidemiology / Q000235:genetics*