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RESEARCH TRIANGLE PARK, N.C. – Stillbirths occur in one out of every 160 births in the United States and, despite extensive evaluation, 25 to 60 percent of these prenatal deaths remain unexplained.
A new genomic technology, called microarray analysis, could contribute to greater understanding of what causes stillbirths by identifying cases of genetic abnormalities, according to results reported by a National Institutes of Health research network established to find the causes of stillbirth as well as ways to prevent or reduce its occurrence. RTI International serves as the data coordinating and analysis center for the network and co-authored the study.
The study, published in the December 6 issue of The New England Journal of Medicine, found that microarray analysis was more successful than conventional karyotype analysis at detecting genetic abnormalities in stillbirth samples.
Microarray analysis detects small deletions and duplications in DNA and, unlike karyotype analysis, can be performed on non-living cells.
“Genetic abnormalities have been associated with 6 to 13 percent of stillbirths, but the true prevalence may be higher,” said Grier Page, Ph.D., a senior statistical geneticist at RTI International and one of the paper’s authors. “We found microarray analysis to be especially valuable in analyses of stillbirths with congenital anomalies or in cases in which karyotype results cannot be obtained.”
Karyotype analysis is the current standard method for detecting chromosome abnormalities, and involves staining the chromosomes and examining them visually using a microscope.
The researchers performed microarray and karyotype analysis on tissue samples from 532 stillbirths in five different geographic areas. Microarray analysis yielded results more often than karyotype analysis (87.4 percent compared to 70.5 percent), and provided better detection of genetic abnormalities, such as trisomy 21, trisomy 18, monosomy X and others.
“The primary benefit of using microarray analysis over karyotype analysis is the greater likelihood of obtaining a result because of the ability to analyze non-living tissue,” Page said. “We were able to obtain a result in nearly 25 percent more cases than we would have done using karyotype analysis alone.”
Microarray analysis also identified more genetic abnormalities among 443 antepartum stillbirths (8.8 percent versus 6.5 percent) and 67 stillbirths with congenital anomalies (29.9 percent versus 19.4 percent). While microarray analysis is currently more expensive than standard karyotype analysis, the authors note that they expect the cost will decrease and may be further offset by the higher yield of results.
The study was conducted as part of the National Institute of Child Health and Human Development Stillbirth Collaborative Research Network. RTI International is the data coordinating and analysis center for the network. The Network is tasked with determining the extent and causes of stillbirth-fetal death at 20 or more weeks gestation.
