Down syndrome in sub-Saharan Africa

Abstract

Down syndrome (DS), which is now recognised as the commonest cause of congenital mental disability in developed countries, was first described by Langdon Down in 1866. However, not until 1955 did Luder and Musoke recognise and describe the first black African children with DS. Before this, no less an authority than Jellife had commented that 'Mongolism occurs commonly in all ethnic groups, with the possible exception of people of African extraction amongst whom it would appear to be uncommon or even rare.' In justifying his comment he noted his six year experience with African children in the southern Sudan and Nigeria during which time he saw no DS cases. He then proceeded to suggest that in view of the apparent rarity of DS in 'unmixed African populations on the African continent', the fact that the condition was common in Jamaican children suggested that the causative factor must therefore be acquired from non-African, that is, white or Asiatic, sources. DS has become one of the most researched and well documented genetic conditions. This volume of work up till 1980 comprised over 6000 papers with an even larger number of publications appearing in print since then. However, to the best of the author's knowledge, to the present fewer than 25 papers have dealt, specifically or in passing, with DS in African populations south of the Sahara. It took until 1982 for Adeyokunnu to lay to rest the myth of the rarity of DS in Africans. Since then, very little further research has been undertaken, possibly because of the emphasis in Africa on the eradication of malnutrition and infectious diseases, coupled with the continuing lack of awareness of the incidence of DS and difficulties inherent in the diagnosis of the condition in African neonates.