Related Experiment Videos
Long-bone growth in fetuses with Down syndrome
J FitzSimmons1, S Droste, T H Shepard
1Department of Obstetrics and Gynecology, University of Washington, Seattle.
American Journal of Obstetrics and Gynecology
|November 1, 1989
Summary
Fetal limb lengths, particularly in the upper extremities, are shorter in cases of Down syndrome (trisomy 21). However, femur length ratios are less effective predictors of Down syndrome than maternal factors.
Area of Science:
- Prenatal diagnosis
- Genetics
- Fetal development
Background:
- Short stature is a known characteristic of Down syndrome.
- Reduced femur length in fetuses can indicate a high risk of trisomy.
Purpose of the Study:
- To investigate the relationship between limb lengths and gestational age in fetuses with trisomy 21.
- To evaluate the efficacy of limb length measurements as a predictor for Down syndrome.
Main Methods:
- Postmortem measurements of femur, tibia, fibula, humerus, radius, and ulna were taken from 37 fetuses with trisomy 21 and 174 controls.
- Limb lengths were compared to gestational age using regression analysis.
- Ratios of actual to expected femur lengths were calculated.
Main Results:
- Limb bones in fetuses with trisomy 21 were generally shorter than normal, though differences were often small.
- Six fetuses (16.2%) with Down syndrome had femur length ratios below 0.91.
- Upper extremity bones showed shorter lengths more frequently than lower extremity bones.
Conclusions:
- Limb bone shortening occurs in Down syndrome fetuses but is not a highly sensitive predictor.
- Maternal age and serum alpha-fetoprotein are more effective Down syndrome screening markers than femur length ratios.