β-Thalassemia Mutations in Jamaica: Geographic Variation in Small Communities

Abstract

Over the last 43 years, surveys of over 200,000 subjects in Jamaica have identified β-thalassemia (β-thal) mutations. In most, these genes were detected at birth in patients with sickle cell-β-thal and so the prevalence and distribution would not be influenced by subsequent clinical course. There were two newborn populations, 100,000 deliveries in the corporate area between 1973-1981 and 84,940 in south and western Jamaica between 2008-2016. A third population, which derived from the Manchester Project in central Jamaica, screened 16,612 secondary school children, aged predominantly 15-19 years, and identified 150 students with the β-thal trait and 11 with sickle cell [Hb S (HBB: c.20A>T)]- or Hb C (HBB: c.19G>A)-β-thal. The latter patients may have been subject to symptomatic selection, but this should not have affected those with β-thal trait. Of the 24 different molecular mutations, β⁰-thal genes accounted for 10.0-27.0% of these groups and most common was IVS-II-849 (A>G) (HBB: c.316-2A>G). Of the β⁺ mutations, seven subjects had severe genes with low levels of β chain synthesis but the majority were benign mutations in the promoter region. The –29 (A>G) (HBB: c.-79A>G) mutation dominated in the newborn study in Kingston, similar to experiences in Guadeloupe and African Americans but the –88 (C>T) (HBB: c.-138C>T) mutation was more common among school students in central Jamaica. Caribbean populations are genetically heterogeneous but variations within different parts of Jamaica is of potential importance for prenatal diagnosis and genetic counseling. This information may also be useful among the large Jamaican diaspora.

Keywords:

• β-Thalassemia (β-thal) mutation
• Jamaica
• sickle cell disease

Acknowledgments

The support of the Ministry of Health and particularly of the Southern Region is gratefully acknowledged. We also thank the staff of schools in Manchester Parish and of the hospitals in the south and west on Jamaica.

Disclosure statement

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of this article.

Additional information

Funding

This study was supported by the British Medical Research Council as part of its support to the MRC Laboratories, University of the West Indies between 1972-1999 and by the National Health Fund of Jamaica under NHF grant HPP70, and by the Alcoa Foundation from 2008-2013.