A study in the Lancet shows that first cousin unions double the risk of birth defects. An example there, with the Pakistani population in GB, but this would be the case in all ethnic groups.
It was an unusually high death rate among children under 12 in the Pakistani community in Great Britain that initially aroused the curiosity of a group of researchers. Birth defects being the most common cause of infant death in this ethnic group, these scientists therefore sought to understand the reasons for this increased risk.
Their work, which has just been published in the prestigious journal The lancet consisted of analyzing the various factors generally inducing this increased risk of birth defects in children. Tobacco, alcohol or maternal obesity, the authors have scrutinized everything that could have increased this risk in a cohort of 13,776 newborns from Bradford in England, a city made up of great ethnic diversity. On this large sample of births, they first noticed that there were 386 medical records of newborns which concerned children born in Bradford with one or more abnormalities (cardiac, nervous, urinary, pulmonary and chromosomal, such as trisomy 21) between 2007 and 2011. These specialists were thus able to calculate the risk ratios according to the various maternal risk factors and to realize that consanguinity was associated with a doubling of the risk of congenital anomaly. In this study, this particularly concerned mothers of Pakistani origin.
On all the data collected by these researchers 18% of the babies were the descendants of unions between first cousins. These babies were mostly native Pakistanis. The authors therefore conclude that 31% of all abnormalities in children of Pakistani descent could be attributed to inbreeding. An absolute risk of giving birth to a child with a malformation that the authors nevertheless consider low (between 3 and 6%) although not negligible. In addition, these scientists specify to have observed a similar increase in this risk in mothers of white British origin aged over 34 years at the birth of their child.
“This study provides clear and accessible information on these low but avoidable risks” says Professor Neil Small, author of this study. “Our results are valuable in terms of public health, especially for those in charge of prenatal genetics or pediatrics services. More information should be put in place, especially in communities at increased risk, and in consanguineous couples, to help decision-making in matters of reproduction, ”the authors conclude. Note that this publication specifies that consanguineous marriages do not concern in any case, only, the Pakistani community. Many other populations around the world commonly practice this type of union.
This is not the 1time time a study shows that consanguineous unions pose an increased medical risk to their descendants. Previous data had already shown that a child born of a relationship between parents from the same family branch had a higher risk of developing, in particular certain genetic diseases. Each parent transmits in fact, half of his genetic heritage, therefore, the less there is mixing, the more the genes transmitted are similar. So when the father and the mother come from the same family, by uniting, they increase the risk of transmitting one or more of their common genetic mutations, sometimes failing, and therefore the risk of developing a serious disease.
.
