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Book Review: Consanguinity in Context

17 September 2012
Appeared in BioNews 673

Consanguinity in Context

By Professor Alan Bittles

Published by Cambridge University Press

ISBN-10: 0521781868, ISBN-13: 978-0521781862

Buy this book from Amazon UK

'Consanguinity in Context' by Professor Alan Bittles

The title told me that this was the monograph for which I had been waiting. A further delight was that the author was a good friend and colleague. By the way, there are no conflicts of interest (!); Alan Bittles advised my colleagues and me as we planned studies in consanguineous families in the Trent region in the UK during the 1990s and, more recently, in Oman. So, there was extra confidence due to this book's reputable provenance.

This monograph is desperately needed. Western societies, who often chose consanguineous marriage in the past, have grown to fear it and to denigrate communities where it is commonly practiced. Criticisms of consanguineous marriage come from sources expected to be objective, but often failing in this respect. Healthcare workers and laboratory scientists who have investigated disabilities in selected high-risk families have been known to make comparisons without appropriate control subjects. Sometimes, selective arguments, for or against, come from within the communities who often choose cousin marriages (reported in BioNews 573).

The usual culprits then join the chorus. For example, immoderate and ill-informed politicians or other seekers of publicity, who have never attended real patients with disabilities nor looked at healthy control families for comparisons of the burden of disease, may nevertheless add their own honest concerns whilst using crooked thinking. Bittles' book is not just for those in wealthy Western countries, geneticists, other scientists or healthcare workers. It is also for professionals and families with genetic disorders throughout the world.

Despite the unassuming title, this book is packed with carefully collated information, covering all aspects of consanguineous marriage. This includes genetics, culture, religion, legislation, demography, socioeconomics and the relationship to many conditions that occur more often in some marriages between close relatives. The compilation is exhaustive, fascinating and rigorously discussed. Like all good scientists, Bittles does not select data to augment his particular view; he gives all the facts, covering the historical, social, geographical and scientific framework of consanguinity. He also includes many gems, such as Francis Galton's wicked, non-politically correct, comment to Darwin's son, George, who had published one of the first studies of the limited adverse effects of consanguinity. You will now need to read the book to find out what Francis said to his first cousin, once removed!

OK there's the hyperbole. Does this monograph fulfil expectations? My answer is like that of the character Meg Ryan played in the restaurant scene of 'When Harry met Sally': 'Yes, yes, yes, yes...Yes!'.

Every chapter starts with a clear introduction and ends with a commentary that summarises the information available and all key issues. The first chapter covers 'Consanguineous marriage, past and present' and the last 'Consanguinity in context'. The wealth of information in between discusses a range of topics, with the first third dealing with subjects such as religious attitudes and rulings, historic scientific/medical debates and population genetics. Bittles then delves into the influence of consanguinity on reproductive behaviour, early life morbidity and disease in adults. In the final third of this comprehensive book incest, genetic screening, education and counselling are tackled.

Bittles' discussion of genetic screening and counselling made me appreciate how little data there is showing what happens if high-risk affected families with an autosomal recessive disease are provided with non-directive genetic counselling based on an accurate family tree. Gathering this data will surely be better than a general, ill-informed clarion call that cousin marriage be outlawed!

There is so much information here, but it is all relevant, well-validated, significant and stimulating. The book is littered with fascinating facts, such as that in China, Taiwan, Korea and the Philippines, legislation bans first cousin marriage, although China distinguishes between marriages involving the daughter of a father's brother (banned) and marriages involving the daughter of a mother's brother (acceptable)!

In the penultimate chapter there is a thoughtful discussion of when consanguinity can be beneficial to human health, the role of epigenetics and the influence of consanguinity on donor matching for organ transplantation. As I read this chapter, I realised that only if we learn the lessons implicit in Bittles' amazingly comprehensive, and yet readable tome, will the opportunities for good 'blue skies' research into customary cousin marriage be fully realised. Put simply, this book is exactly what is needed to clarify discussions and debates about consanguinity. It deserves to be influential in scientific, political and religious thinking. We should applaud the single author of a major opus by giving his data the attention it deserves.

Buy Consanguinity in Context from Amazon UK.

8 July 2013 - by Dr Victoria Burchell 
Marriage between first cousins could double the risk of any offspring having a birth defect, researchers say...
11 February 2013 - by Robert Pralat 
'Families: Beyond the nuclear ideal' discusses various 'alternative' family forms in Western societies, examining the arguments behind the celebration and criticism of specific types of family that depart from the norm...
4 October 2010 - by Dr Rizwan Alidina and Dr Mohamed Walji 
A Dispatches programme on rare genetic conditions and cousin marriage aired a few weeks ago ignited much debate. Many people commenting on the programme were correct to say consanguinity alone isn't the issue. However, the high rate of autosomal recessive disorders in some communities remains an important issue, regardless of its intricate and complex causes. This needs to be addressed, preferably with input from general practitioners...
6 September 2010 - by Anshu Rastogi 
'When Cousins Marry' (Dispatches) was a difficult film to make. It was painful at times but immensely rewarding in the end. The film was commissioned because it highlighted a potentially avoidable cause of serious disabilities in hundreds of British children each year...
22 March 2010 - by Professor Marcus Pembrey 
A report and analysis promoting Baroness Ruth Deech's views on cousin marriage, published in the Times newspaper on Saturday, makes some serious errors and does nothing to either clarify the true health impact of cousin marriage or help couples at risk of recessive genetic conditions...
31 March 2008 - by Professor Alan Bittles 
First cousin marriage is a topic that frequently evokes distaste and even a sense of moral outrage in the UK and other western countries. Given its sound Biblical tradition (Leviticus 18:7-18) and long-standing legal acceptance this is somewhat surprising, the more so since many famous figures of the...
Comment ( - 02/10/2012)
Read Adam Kuper: Double Singles
It surprises me that Adam Kuper‘s review of books discussing intermarriage and cohabitation among close  relatives neglects to mention the genetic maladies of consanguinity in their offspring (Double Singles, TLS May 18 2012). Kuper briefly skates over the “growing consensus that cousin marriage was dangerous.” Suspicions had long been widely promulgated even before the advent of rudimentary Mendelian genetics. Bondin declared consanguineous marriages to give rise to madness; Devay stated that goitre of the Cagots of the Pyrenees was due to intermarriage; Trousseau claimed it produced epilepsy and deaf-mutes. The effects of interbreeding were accentuated, and of more public interest, in European royal houses, where close-relation marriages had long received papal dispensation as political and dynastic alliances as well as a means to boosting papal coffers. However in Sept 1902, Pope Leo XIII notified the reigning houses of Europe that no more dispensations would be granted, as he had “observed an unfortunate tendency to degeneration among sovereign families.” The papal ban eerily presages the haemophilia that was the cause of the grave illness of Prince Alexei, Czar Nicholas and Alexandra Romanov's only son, born in 1904. Haemophilia had long been recognised as a disease carried by the intermarried royal families of Europe, most notably manifest in the Romanov lineage. Modern genetics tell us that when both unrelated parents carry a disease-related recessive gene, the risk of passing on a serious disease or malformation is 1 in 20. Among first cousins (the most frequent legally approved consanguineous relationship) the risk increases to 1 in 11. A child born of incestuous first degree relatives has a hefty 1 in 3 chance of gaining a hereditary illness. Throughout history and across cultures, consanguinity has served the purpose of retaining family wealth and strengthening ties, but at a great biological cost.
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