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Consanguinity doubled congenital anomaly risk
Consanguinity causes a major increased risk for congenital anomalies; however, absolute risk is low, according to recent study findings published in The Lancet.
“It is important to note that the absolute risk is small (from 3% to 6%), meaning that only a small minority of babies born to couples who are blood relatives or older mothers (older White British mums have an increase in risk from 2% to 4%) will develop a congenital anomaly,” Eamonn Sheridan, MBChB, of the University of Leeds in the United Kingdom, said in a press release.
The study included questionnaire data from 11,396 mothers of children with one or more anomalies from the Born in Bradford study — a prospective birth cohort study of 13,776 babies and their families in which recruitment was taken between 2007 and 2011.
Researchers found that 3% of the participants had a congenital anomaly and rates were 305.74 per 10,000 live births compared with a national rate of 165.9 per 10,000 live births. Risk for anomalies was greater for mothers of Pakistani origin compared with mothers of white British origin (RR=1.96; 95% CI, 1.56-2.46). Eighteen percent of participants were offspring of first-cousin unions. Thirty-seven percent of Pakistani-origin participants were offspring of first-cousin unions.
Consanguinity doubled the risk for congenital anomaly (RR=2.19; 95% CI, 1.67-2.85); however, there was no association with increasing deprivation. Of all congenital anomalies in Pakistani-origin participants, 31% could be attributed to consanguinity. Risk was similar for white British mothers aged older than 34 years (RR=1.83; 95% CI, 1.14-3).
“This is the first study that has been able to explore all causes of congenital anomaly in a population where there are sufficient numbers in both consanguineous and non-consanguineous groups to come to reliable conclusions,” Neil Small, PhD, of the University of Bradford, said. “Clear and accessible information on these small but significant avoidable risks should be widely disseminated to local communities and be included as part of antenatal counseling and in the planning of health care services.”
Disclosure: The study was funded in part by NIH Collaboration for Leadership in Applied Health Research and Care.
