Geoffrey Dean

Geoffrey Dean, who has died in Dublin aged 90, was best known as an epidemiologist who in several studies established the importance of an environmental influence on the pathogenesis of multiple sclerosis. This is regarded as his most important scientific contribution. His work is of particular relevance at present because of increasing evidence that the environmental factor in multiple sclerosis is sunlight exposure. Reduced sunlight exposure results in low vitamin D concentrations and increased susceptibility to autoimmune disease.

Dean’s interest in multiple sclerosis peaked after he arrived in South Africa in 1947 when he observed the marked variation in prevalence of the disease among the different ethnic groups. The prevalence of multiple sclerosis among English speaking white people born in South Africa was only one quarter and among the Afrikaans speaking white people born in South Africa only one 11th, as frequent as that of the immigrants from northern Europe. Subsequently, with John Kurtzke, he established that immigration before the age of 15 led to a reduced risk for the development of multiple sclerosis in immigrants from northern Europe who settled in South Africa. After that age the immigrants brought with them the high risk of multiple sclerosis that pertains to north Europe. These studies, published in the BMJ in 1967 and 1971, showed a strong environmental effect on the development of multiple sclerosis (1967;2:724-30, doi:10.1136/bmj.2.5554.724 and 1971;3:725-9, doi:10.1136/bmj.3.5777.725). At that time an undetermined infectious agent acting in the mid-teens seemed to be the most likely cause.

Dean was one of the few doctors who, in 1965 during the apartheid years, criticised the South African government for the maltreatment of prisoners. He was arrested and narrowly missed imprisonment under the regime thanks to the intervention of medical friends and colleagues in the United Kingdom, including Richard Doll and the president of the Royal College of Physicians in London, Lord Platt.

Dean moved to Ireland in 1968 to become the first director of the newly formed Medico-Social Research Board. With Marta Elian, he published several papers on the reverse effects of migration from countries with a low risk of multiple sclerosis to the high risk UK. He established that migrants from the West Indies and India to the UK brought with them a low risk of multiple sclerosis but their offspring born in the UK developed a much higher risk that pertains to the UK. He conducted epidemiological studies with local neurologists in several countries, including Ireland, Spain, and Cyprus. Latterly he was particularly interested in the marked disparity between the low prevalence of multiple sclerosis in Malta and the much higher prevalence in Sicily, two islands only 50 km apart. His last publication, in Neurology in 2008, at the age of 89, in conjunction with Maltese neurologists and Alaistair Compston’s team in Cambridge UK, found that the difference in prevalence was not explained by HLA genes; Geoffrey was keen to pursue further work on this enigma (Neurology 2008;70:101-5).

His other main scientific contribution was on porphyria variegata, which he first described in South Africa in the 1950s. He painstakingly established the family tree of people carrying the porphyria gene, going back to the first affected person, Gerrit Renier Van Rooyen, who arrived in South Africa in 1685 during the early Dutch settlement, again published in the BMJ (1955;2:89-94, doi:10.1136/bmj.2.4931.89). His interest in porphyria led subsequently to much correspondence on the subject of the royal malady and the insanity of King George III, which was, wrongly in Dean’s view, attributed to porphyria by Ida MacAlpine and Richard Hunter. He also published widely on the epidemiology of several other disorders. Between the first publication in 1950, in the BMJ, on barium carbonate poisoning and the last in 2008, there were a total of 120 papers and several books, including an autobiography, The Turnstone, in 2002.

Born in December 1918 in Wrexham, North Wales, where his father was a local bank manager, Dean was educated at Ampleforth and started his medical studies in 1936, aged 17, at Liverpool University, qualifying in June 1943. He served as a medical officer with Bomber Command from 1943 to 1945. He married Noni Devlin in June 1944. In postwar England the prospects for advancement as a doctor were daunting, and Dean took a ship to South Africa as the ship’s doctor, settling eventually in Port Elizabeth and practising as a consultant physician. After moving back to Dublin in 1968 he was later appointed a Commander of the Order of the British Empire by Queen Elizabeth; University College Dublin conferred on him a doctorate of science; and the Royal College of Physicians in Ireland conferred on him its fellowship.

In his last decade he developed prostatic carcinoma and fibrosing alveolitis. He fought against both illnesses with tenacity and was determined to live to contribute further to the understanding of multiple sclerosis and to publish the next paper. He leaves his second wife, Maria, and four children.