Prenatal chromosome analysis is currently indicated for couples who have greater than a 0.5% risk of having a chromosomally abnormal child. This guideline is based on the possible risk of amniocentesis and the limited availability of services. Because the recurrence risk is assumed to be less than 0.5% for nonfamilial chromosome rearrangements and some aneuploidies, prenatal chromosome diagnosis for future pregnancies is not indicated for parents of a child with one of these disorders. However, most genetic counselors and physicians are aware that these parents usually request prenatal diagnosis because of their high concern about having another affected child. We recently performed prenatal chromosome diagnosis for a couple who had this type of concern, as a result of delivering an infant with the cri-du-chat syndrome. We report the prenatal diagnosis of a 47,XYY chromosome complement in the fetus and the subsequent genetic counseling.
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