In this issue of JAMA, Haque et al1 report the results of the use of high-throughput molecular biologic techniques for prenatal carrier screening. As numerous reports in JAMA2,3 and elsewhere have illustrated, the technique is now in fairly wide use in the evaluation of patients with undiagnosed but presumably genetic disorders and in the detection of drug sensitivity and resistance mutations in malignant tumors. Initial results of these studies have yielded some surprising findings.