Predicting the risk of cystic fibrosis with echogenic fetal bowel and one cystic fibrosis mutation.
OBJECTIVE
To assess fetal risk for cystic fibrosis when echogenic bowel and one cystic fibrosis mutation are detected.


METHODS
A hypothetical cohort of 1000 women with singleton pregnancies and echogenic fetal bowel during the second trimester was used to determine the probability of cystic fibrosis when one cystic fibrosis transmembrane conductance regulator mutation was detected. The risk of cystic fibrosis was calculated using the range of prevalence of cystic fibrosis in fetuses with echogenic bowel reported in the literature. Risk calculations for fetuses of Ashkenazi Jewish, Northern European, African-American, Hispanic, and Asian descent accounted for carrier frequencies and mutation detection rates specific to each ethnic group.


RESULTS
As the assumed prevalence of cystic fibrosis increases from 1-25%, the probability that a white fetus with one mutation and echogenic fetal bowel actually has cystic fibrosis increases from 4.8% to 62.5%. Assuming a 2% risk of cystic fibrosis with echogenic fetal bowel, an Ashkenazi Jewish fetus and an Asian fetus with echogenic bowel and one mutation have a 3.1% and 72% risk of cystic fibrosis, respectively. The probability of cystic fibrosis in a nonwhite fetus is between those two extremes.


CONCLUSIONS
The probability of cystic fibrosis after detection of echogenic bowel and one cystic fibrosis mutation varied among ethnic groups. Even at the highest prevalence of cystic fibrosis, most white fetuses will not have cystic fibrosis. In nonwhite populations almost half of these fetuses will have cystic fibrosis, even at the lowest prevalence of cystic fibrosis.
Bosco
A F
AF
Department of Obstetrics and Gynecology, Brigham and Women's Hospital, Boston, Massachusetts 02115, USA.
Norton
M E
ME
Lieberman
E
E
D003550:Cystic Fibrosis / Q000453:epidemiology* / Q000208:ethnology; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000235:genetics*; D005260:Female; D005817:Genetic Counseling; D006801:Humans; D007422:Intestines / Q000000981:diagnostic imaging*; D009154:Mutation; D011237:Predictive Value of Tests; D011247:Pregnancy; D011262:Pregnancy Trimester, Second; D015995:Prevalence; D018570:Risk Assessment; D014463:Ultrasonography
C505032:CFTR protein, human; D019005:Cystic Fibrosis Transmembrane Conductance Regulator