Sickle cell anaemia: maps and newborn estimates

25 October 2012

In 2010 around 300,000 babies were born with sickle cell anaemia, a serious blood disorder which can be fatal if untreated, and 5.5 million newborns inherited the sickle cell gene, a new study suggests.

Whilst the 5.5 million who only inherit the gene will usually not present any clinical complications, these individuals could still pass this gene on to their offspring and give birth to babies suffering from sickle cell anaemia. Accurate estimates of the numbers and geographical distribution of those affected is vital for effective prevention and treatment policies to be put in place.

The research by the Malaria Atlas Project (MAP; http://www.map.ox.ac.uk), a multinational team of researchers funded mainly by the Wellcome Trust, maps the geographical contemporary distribution of sickle haemoglobin – a genetic disorder causing sickle cell anaemia. It also estimates the number of newborns affected by this condition.

Historically, the sickle cell gene (haemoglobin S or HbS) was common in people of African, Mediterranean and Indian origin but, following human migrations, it is now much more widespread. The MAP team’s estimates suggest that about half of the affected newborns are born in Nigeria, the Democratic Republic of the Congo, and India, but important uncertainties remain in large parts of these countries due to a lack of data.

A report of the research is published today in The Lancet.

Dr Fred Piel from Oxford University’s Department of Zoology, who led the research, said: ‘Sickle cell disease has now been studied intensively for more than a hundred years but our knowledge about its current distribution and burden is really poor. Our aim was to use available evidence-based epidemiological data from the literature combined with modern mapping and modelling methods to come up with the best maps and estimates. In the future, we hope that accessing additional data, including from national screening programmes, would help further refine these results.’

This study provides the first rigorous assessment of the contemporary distribution of this disorder and uses state-of-the-art methodology to estimate the number of newborns affected globally, regionally and nationally. The team was inspired by work conducted by Frank B Livingstone, in the 1970s and 80s. Although ageing, his global database on inherited blood disorder frequencies still represents a unique resource. There is growing awareness about the burden of genetic blood disorders, sickle cell disease in particular, and it is crucial for public health policy makers to access evidence-based quantitative epidemiological data allowing the assessment of the current situation and to measure changes in the future. The data will be released in open access on the MAP website (www.map.ox.ac.uk).

Professor Sir David Weatherall, who has shared his unique expertise in the field and provided exceptional support to this project, said: ‘The inherited haemoglobin disorders, notably sickle cell disease and the different forms of thalassaemia, are by far the commonest monogenic diseases and the vast majority of births affected occur in low or middle income countries. Previous work suggested that their distribution varied considerably even within short geographical distances and data regarding their true frequency is extremely difficult to obtain. Hitherto, they have been largely ignored by the international health community and it is absolutely vital that better information is obtained regarding their true frequency so that their control and better management can be achieved, particularly in the developing countries where they are so common. The impressive work described in this paper provides an invaluable base for future work of this kind.’

For further information visit http://www.map.ox.ac.uk or contact Dr Fred Piel of Oxford University on +44 (0)1865 271 132 or email fred.piel@zoo.ox.ac.uk or Professor Simon Hay of Oxford University on +44 (0)1865 271 243 or email simon.hay@zoo.ox.ac.uk

An image showing areas with high predicted frequencies of sickle haemoglobin [credit: MAP] is available here: http://www.ox.ac.uk/images/hi_res/15799_Sickle_cell_anaemia_MAP.jpg

Alternatively contact the University of Oxford Press Office on +44 (0)1865 283877 or email press.office@admin.ox.ac.uk

Notes for Editors:

  • A report of the research, ‘Global epidemiology of sickle haemoglobin in neonates: a contemporary geostatistical model-based map and population estimates’, by Piel, F.B., Patil, A.P., Howes, R.H., Nyangiri, O.A., Gething, P.W., Dewi, M., Williams, T.N., Weatherall, D.J. and Hay, S.I., is published in The Lancet.
  • The Malaria Atlas Project (MAP) is funded by The Wellcome Trust (UK) to assemble medical intelligence and survey data to provide evidence-based maps on the distribution of malaria risk, human population, disease burdens, mosquito vectors, inherited blood disorders and malaria financing and control worldwide. The maps and estimates generated are the results of a collaboration between scientists in the UK, Kenya and Indonesia. For further information visit http://www.map.ox.ac.uk
  • The Wellcome Trust is the largest charity in the UK. It funds innovative biomedical research, in the UK and internationally, spending over £600 million each year to support the brightest scientists with the best ideas. The Wellcome Trust supports public debate about biomedical research and its impact on health and wellbeing. http://www.wellcome.ac.uk
  • The Department of Zoology, within the Mathematical, Physical and Life Sciences Division at the University of Oxford, has a long-standing reputation for world class research and teaching. Research in the Department is organised into several research themes; these span a broad spectrum of biology ranging from ecology and behaviour, through to molecular evolution, development and infectious disease biology. http://www.zoo.ox.ac.uk/
  • The Kenya Medical Research Institute (KEMRI) is a Kenya government parastatal with the responsibility for health research to improve the health of Kenyans. It is one of the most well developed national research institutes in Africa with a network of centres across Kenya.http://www.kemri-wellcome.org/
  • The Eijkman Institute is the most prestigious and internationally acclaimed research institution ever established in Indonesia. It is a renewed, non-profit, government funded research institute conducting basic research in medical molecular biology and biotechnology. http://www.eijkman.go.id/
  • The Weatherall Institute of Molecular Medicine (WIMM) is a strategic alliance between the Medical Research Council and the University of Oxford. The WIMM fosters research in molecular and cell biology with direct application to the study of human disease. http://www.imm.ox.ac.uk/