Consanguinity and child health

Marriage between close biological kin is widely regarded as genetically disadvantageous in contemporary Western societies, but consanguineous unions remain preferential in North Africa, the Middle East and large parts of Asia, with marriage between first cousins particularly popular. Many major populations also are subdivided into endogamous communities that have distinctive breeding pools. It is in these populations that intra-community marriage principally governs the spectrum of observed diseases. Because of population subdivision, and because the poorest sections of all populations are most disadvantaged in terms of health and health care provision, there are difficulties in assessing the effects of consanguinity alone on morbidity and mortality. A positive association has been repeatedly shown between consanguinity and childhood morbidity due to the expression of detrimental recessive genes. Examples include deafness, retinal dystrophies, intellectual and developmental disability and complex congenital heart disease. Increased incidences of thalassaemia and other haematological disorders also are reported in many populations. Given the recent patterns of immigration, many Western countries have continued exposure to consanguineous unions, which necessitates the provision of more focused resources to improve the delivery of prospective genetic counselling, prenatal testing, treatment and community care. In communities where consanguineous marriage forms an integral and valued part of the cultural tradition, external attempts to discourage close-kin unions at the population level are inappropriate and unlikely to be successful.