Family history of sickle cell anaemia: sickling test, haemoglobin electrophoresis.
Tests to be Done
Traditionally in the Gulf and Middle Eastern communities, as well as the Pakistani and Muslim Indian communities, inter-marriage within the family was very common. However, in the West this practice has long been held as somewhat taboo, due to concerns about the possible genetic diseases passed on through intermarriage.
The latest research
However, recent research by human geneticists have found that the medical risks of same blood marriages could have been overstated and it may even be natural to marry your cousin. The issue is a contentious one with many disagreements between geneticists investigating inbreeding.
But new studies show these fears may be unfounded.
Professor Alan Bittles, foundation professor at Edith Cowan University in Australia has been studying communities in the Middle East for more than 20 years and says that there are a lot of misconceptions regarding marriage to relatives and many are rooted in religion and culture, rather than rational observation.
He points out that there are social, economic and perhaps even biological advantages in marrying fairly close relatives and says that it is a case of weighing up the risks against the benefits. Although his views appear to be quite radical he maintains that if inbreeding were all that detrimental, Middle East populations would have died out long ago.
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First cousin marriages are the most common form of same-blood unions and this practice is particularly popular in the Middle Eastern countries where marriage to relatives currently account for 20 to over 50 per cent of all unions with no current evidence to suggest a significant decline in the practice.
About 800 million people, or almost a sixth of the world population, live in countries where marriages between people who are second cousins or closer is common. A further 2.8 billion people live in countries in which one to 10 per cent of all marriages are between relatives. The highest rates are in parts of India, Pakistan and the Middle East. The practice is particularly popular in rural areas and among the poorest and least educated groups.
Here in the Gulf marriage between two closely related individuals is widely practiced. In fact 52 per cent of marriages in Saudi Arabia are consanguineous (within the family) with 39 per cent of those being to first cousins. In the UAE the figure is about 37 per cent.
A Gulf tradition
There are many reasons given for the popularity of these unions, but the most common are a strong family tradition of marriage between relatives, the maintenance of family structure and property. Another perceived benefit is women who typically move in with their in-laws are thought to have a far greater chance of getting on with them if they are related. There are also financial advantages to these unions. Another aspect is greater marriage stability and durability, you are less likely to marry someone and then get a nasty shock about their health or personality. Professor Bittles says: "In most Middle Eastern countries it is considered an extremely risky business to marry into a family that you know nothing about."
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The medical risk of kin marriage is that children could inherit a harmful recessive gene from each parent. The result could be a single-gene disorder like sickle cell anaemia, thalassemia, retinitis pigmentosa, which causes blindness, and homocystinuria and phenyiketonuria, metabolic disorders that cause mental retardation. Other risks may involve cardiovascular disease, cancer and diabetes, which have multiple genetic and environmental factors.
Although lack of resources has limited the collection of data on single-gene disorders in countries with highly inbred populations, mortality figures do give some indication of the impact of inbreeding. Studies on children of first cousins indicate that miscarriages and child death was between one to four per cent higher than in children of unrelated couples. However, a study in Pakistan suggested that influences such as maternal age and birth interval played a bigger role in early death and when these factors were considered, the contribution of inbreeding to miscarriages and early childhood death fell.
The medical risk is considered to be higher in populations with multiple in breeding loops and it has been found that babies in one such community have almost four times the rate of single-gene disorders of those in a comparison group.
But there is evidence suggesting that the human genome may be equipped to cope with a certain level of inbreeding, perhaps to lock in advantageous genes. Professor Bittles is just completing a study of populations in India and Pakistan to establish how many people have inherited double copies of recessive genes, both harmful and harmless. As expected, there was less genetic variation than in outbred populations. But, his research discovered that there was much more variation than would be expected in populations that had been inbreeding for thousands, or perhaps hundreds of years.
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But cousin marriages are expected to decline in the future irrespective of culture or social norms because of factors such as the reduction of family size. Which will mean as the family size reduces, double first cousin and uncle-niece marriages in particular will become increasingly difficult to arrange within the accepted norms of the husband or wife's age range. However, this slide will not be uniform across all populations but will be mainly seen in urbanized populations and among couples who share higher education and marry later.
Professor Bittles says that it is important for families and communities where kin marriage is practiced widely to guard against undesirable outcomes of these unions by having an efficient screening programme and making greater efforts to initiate community based genetic counselling.
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Maha (not her real name) and her young husband married three years ago. They were both young and healthy or so they thought. Their parents were very pleased with the marriage after all they knew these two young people were going to make out just fine. They were family, no nasty shocks to be revealed. Maha and Aziz were first cousins.
They felt no need to have a blood test, they knew their relatives and many had married cousins, it was a common occurrence and in this family a strong tradition. When Maha got pregnant with her first baby, everyone was delighted they hoped for a little boy but would have been just as delighted with a daughter. Maha's pregnancy progressed normally. On August 8, 1998 their little girl was born, severely handicapped and blind. The baby had inherited a deadly recessive gene. Maha and Aziz were heartbroken. Maha sobbed and said: "If only I had known the risks, we would have had all the necessary tests. But we did not know anything about human genetics." Sadly their baby girl did not live, but they are hopeful that with the proper medical care and counselling they may still have a chance of becoming the parents of a healthy baby.
G6PD deficiency: specific blood tests to be performed.
Children born with mental retardation in family: check out chromosone studies in the couple planning to get married.
If any specific disease is identified in a particular family, it may be worth seeking medical advice and carrying out appropriate tests before planning the marriage.
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Courtesy: Arabian Woman