Funding sources: The Australian Red Cross Blood Service (the Blood Service) and Australian governments fully funded the Blood Service for the provision of blood products and services to the Australian community.
Strategy for managing maternal variant RHD alleles in Rhesus D negative obstetric populations during fetal RHD genotyping
Article first published online: 4 NOV 2013
© 2013 John Wiley & Sons, Ltd.
Volume 34, Issue 1, pages 56–62, January 2014
How to Cite
Hyland, C. A., Gardener, G. J., O'Brien, H., Millard, G., Gibbons, K., Tremellen, A., Ochoa-Garay, G., Flower, R. L. and Hyett, J. A. (2014), Strategy for managing maternal variant RHD alleles in Rhesus D negative obstetric populations during fetal RHD genotyping. Prenat. Diagn., 34: 56–62. doi: 10.1002/pd.4253
Conflicts of interest: Gorka Ochoa-Garay is an employee of Progenika Inc, manufacturer of BLOODchip Reference v4.
- Issue published online: 2 JAN 2014
- Article first published online: 4 NOV 2013
- Accepted manuscript online: 5 OCT 2013 01:46AM EST
- Manuscript Accepted: 1 OCT 2013
- Manuscript Revised: 30 SEP 2013
- Manuscript Received: 8 AUG 2013
- The Australian Red Cross Blood Service (the Blood Service) and Australian governments fully funded the Blood Service for the provision of blood products and services to the Australian community.
- Australian governments
Fetal RHD screening programs that aim to reduce unnecessary antenatal anti-D prophylaxis are being introduced into clinical practice. Strategies to manage women serologically typed as Rhesus D negative who have maternal RHD variants are needed. This study describes maternal RHD allelic variants detected in nonselected and alloimmunised Rhesus D negative obstetric populations and explores a mathematical approach to identify these variants.
Fetal RHD status was defined by testing cell-free fetal DNA in maternal plasma. Women at risk of an RHD variant were identified by selection for C and E haplotypes or by recognition of low polymerase chain reaction cycle threshold on fetal RHD typing. Maternal RHD alleles were defined by SNP profiling or sequencing.
The prevalence of RHD variants in nonselected and alloimmunised groups was 1% (6/603) and 5.5% (6/110), respectively (p < 0.001). An inverse association between RHD cycle threshold values and gestational age was described by a linear model (p < 0.001). Standard residual values with a Z score threshold of −3.00 would have detected all maternal variants with one (1/713) false positive.
The prevalence of maternal RHD variants was significantly higher in alloimmunised cases. The causative mechanism for this needs further investigation. Mathematical modeling simplifies the detection of maternal RHD variants. © 2013 John Wiley & Sons, Ltd.