Prenatal cytogenetic diagnosis of the fragile X syndrome in amniotic fluid: calculation of accuracy.
We have completed over 350 prenatal diagnoses for the fragile X [fra(X)] syndrome using amniotic fluid, chorion villus specimen (CVS), fetal blood sampling and molecular methods. A total of 300 amniotic fluid specimens have been received for prenatal diagnosis of the fra(X) syndrome. There was a documented family history of fra(X) in 170/300 amniotic fluid cases, and 23/170 were correctly identified as cytogenetically fra(X) positive (16 male; 7 female). Three males were false-negative, and one female was fra(X) negative but identified as a probable carrier by RFLPs. No fra(X) positive or false-negative results were found in the absence of a fra(X) family history. Because the a priori risk for the fra(X) syndrome for each pregnancy was different and widely variable, the determination of the accuracy of the prenatal diagnosis results requires a consideration of these variables. On this basis, the calculated accuracy of prenatal cytogenetic diagnosis for the fra(X) syndrome is approximately 97%. This accuracy can be improved further with the simultaneous use of molecular methods, especially in view of recent developments.
Shapiro
L R
LR
Department of Pediatrics, New York Medical College, Thiells.
Wilmot
P L
PL
Fisch
G S
GS
D003582:Cytogenetics / Q000706:statistics & numerical data*; D005260:Female; D005600:Fragile X Syndrome / Q000175:diagnosis* / Q000235:genetics; D006801:Humans; D008297:Male; D011247:Pregnancy; D011296:Prenatal Diagnosis / Q000706:statistics & numerical data*; D012680:Sensitivity and Specificity