In 2013, a leading British medical journal the Lancet published a research report about the risk factors for congenital abnormality. Congenital anomalies, also known as birth defects, are structural deformities that develop in the uterus or arise from birth or neonatal trauma. Although 'congenital' implies 'inborn', these anomalies are not always genetic in origin, but have chromosomal, genetic and environmental causes. The article was based on analysis of data from a multi-ethnic cohort of 13,776 babies born in Bradford, Yorkshire, between 2007 and 2011. The authors were interested in understanding why there are ethnic differences in rates of congenital anomaly. They sought to identify associations with known risk factors, specifically poverty, maternal age, educational level, parental consanguinity, alcohol consumption and smoking behaviour.
Such questions are particularly significant in Bradford, one of the UK's poorest cities, and home to around ten percent of England's Pakistani Muslim population. In the UK overall, rates of infant death and childhood illness are highest in babies of Pakistani ethnicity, and most of this mortality and morbidity is due to congenital anomalies. The Bradford researchers found that, according to the study, the highest proportion of congenital anomalies were seen in the 5127 babies born to Pakistani parents. They also observed that 60 percent of the Pakistani babies had parents who were consanguineous – related as second cousins or closer – and 37 percent had first-cousin parents. In the analysis of risk factors, parental consanguinity was associated with about one-third of the anomalies in Pakistani babies. Overall, it doubled the two percent background risk for congenital anomaly, and its effect was independent of poverty. This risk level was determined to be similar to the risk associated with mothers of white British origin over 34 years old.
To a paediatrician or clinical geneticist working in Bradford these observations would probably not be surprising. For over two decades, clinicians working in areas of substantial Pakistani settlement have been observing more metabolic and neurodegenerative developmental problems in babies born to Pakistani parents than in white British babies. The new study confirmed this observation. A higher frequency of birth defects has often been attributed to the elevated risk of recessive genetic conditions – many of them very rare – associated with parental consanguinity. In medical circles at least, this risk is well known, and was reported in a number of earlier British studies. In 1993, for instance, a similarly elevated risk for birth defects associated with parental consanguinity was reported from a five-year prospective study of nearly 5000 babies born in Birmingham, in the Midlands, which also has a substantial Pakistani population.
The cousin marriage question
One of the reasons why a new study was important is that, despite the earlier evidence, there has been continuing scepticism over the meaning and implications of the link between parental consanguinity and birth defects. This scepticism has prevailed both within sections of the Pakistani population and outside of it, particularly among those aware of stereotypically negative and racist attitudes towards non-white minorities. Intense controversy has raged in public debates since the 1990s over this issue. Critics have argued that the high rates of infant death and long-term illness in Pakistani children could equally be caused by poverty, unequal access to prenatal care for mothers, low rates of abortion of severely affected foetuses, poor quality obstetric experiences and other developmental or environmental factors. It would therefore be necessary to examine parental consanguinity alongside the other factors associated with adverse birth outcomes, including racism in service delivery to a disadvantaged minority group. Without a more rounded picture, the clinical attention to "consanguinity and related demons", as Waqar Ahmad argues in his 1996 essay on science and racism in the debate on birth outcomes, becomes a new racism by pathologising a minority cultural practice.