Detection rate of quadruple-marker screening determined by clinical follow-up and registry data in the statewide California program, July 2007 to February 2009.

OBJECTIVE: To evaluate the efficiency of California's quadruple-marker screening program and construct receiver-operating characteristic (ROC) curves. METHODS: This study included the screening records of 552 941 women during July 2007 to February 2009. The screen-positive women received clinical follow-up services at state-approved centers. We used the California Chromosome Defect Registry which includes clinical, laboratory, and demographic data from the prenatal diagnostic centers, cytogenetic laboratories, hospitals, and prenatal care providers. Risk calculations, screen-positive rates (SPRs), detection rates (DRs) for chromosomal abnormalities, and 95% confidence intervals (95% CIs) were determined. ROC curves comparing the quadruple-marker to triple-marker screening were constructed. RESULTS: The DR and SPR for trisomy 21 (N = 827) during the quadruple-marker time period were 75.7% (95% CI 72.8-78.6%) and 3.75% (95% CI 3.70-3.80%) compared with 77.4% (95% CI 75.0-79.7%) and 5.4% during the triple-marker phase. The DRs were 78.2% (95% CI 75.0-81.4%) with ultrasound dating and 66.9% (95% CI 59.7-74.0%) for last-menstrual-period-dated pregnancies. For trisomy 18, triploidy, and trisomy 13, the DRs were 84.3, 95.7, and 43.5%, respectively. CONCLUSIONS: The DR for trisomy 21 in California's statewide quadruple-marker screening is very similar to the Program's previously reported DR using triple-marker screening. However, this was achieved at a lower SPR, demonstrating improved screening performance.

Triple-marker prenatal screening program for chromosomal defects.

OBJECTIVE: To examine screening performance of California's triple-marker screening program, using data from a statewide registry for chromosomal defects. METHODS: This study included 752,686 women who received a screening risk and had an expected date of delivery between July 2005 and the end of June 2007. Follow-up diagnostic services for screen-positive women were performed at state-approved centers. Data on diagnostic outcomes from these visits were entered into the California Chromosomal Defect Registry (CCDR). Other CCDR sources include mandatory reporting by all cytogenetic laboratories and hospitals and outcome data forms submitted by prenatal care providers. RESULTS: The observed detection rate for Down syndrome (N=1,217) was 77.4%. It varied significantly by gestational dating method and maternal age. The rates for women aged younger than 35 years and 35 years and older were 62.4% and 94.0%, respectively. The detection rates were 81.3% for ultrasound-dated pregnancies and 67.5% for last menstrual period-dated pregnancies. For Turner syndrome, trisomy 18, triploidy, and trisomy 13, the detection rates were 79.4%, 82.5%, 98.1%, and 36.0%, respectively. The positive rate for Down syndrome was 5.4%. Of women with a Down syndrome fetus who were screen positive, only 49.5% opted for amniocentesis. Of women who obtained results from amniocentesis indicating a Down syndrome fetus, 61.4% had an elective termination, 26.2% had a live birth, 4.5% had a death or miscarriage, and 7.9% had an unknown outcome. CONCLUSION: The observed performance of this large triple-marker screening program exceeds generally predicted detection rates for Down syndrome. This study methodology will be used to measure the performance of subsequent screening enhancements. LEVEL OF EVIDENCE: III.

Characterization of beta-globin haplotypes using blood spots from a population-based cohort of newborns with homozygous HbS.

PURPOSE: A population-based cohort from three state newborn screening programs was used to describe beta-globin gene cluster variation. METHODS: Blood spots from newborns homozygous for HbS were genotyped for five restriction fragment length polymorphisms (RFLPs) to construct beta-globin haplotypes. Haplotype distributions were compared by race/ethnicity and sex. Expected heterozygosities were calculated and compared with observed heterozygosities. RESULTS: Haplotype distributions did not differ between sexes for either blacks or Hispanics. Neither racial/ethnic group deviated from Hardy-Weinberg equilibrium; however, Hispanics had higher heterozygosity at two RFLPs compared with blacks. CONCLUSION: The differences between populations probably reflect recent migration and admixture rather than selection.