Burden, genotype and phenotype profiles of adult patients with sickle cell disease in Cape Town, South Africa

Abstract

Background. An exponential increase in the number of sickle cell disease (SCD) patients in paediatric services in Cape Town, South Africa, has been reported. The trend in adult/adolescent services has not been investigated.

Objectives. To evaluate epidemiological trends of SCD and the profile of patients affected by SCD attending the Haematology Clinic at Groote Schuur Hospital (GSH), Cape Town.

Methods. (i) A retrospective review of the number of SCD patients over the past 20 years; (ii) a cross-sectional analysis of clinical and haematological characteristics of SCD patients; and (iii) molecular analysis of the haemoglobin S mutation, the haplotype in the β-globin-like genes cluster, the 3.7 kb α-thalassaemia gene deletion and 19 selected single-nucleotide polymorphisms (SNPs) associated with fetal haemoglobin (HbF) levels.

Results. From 1995 to 2016, 81 adolescent/adult patients with SCD were registered, mostly originating from other African countries (n=61, 75.3%). There was an increase of over 200% in new cases (n=47) during the last quarter of the two decades investigated. Data from 34 of 58 regular attendees (58.6%) were analysed. The mean age of the patients was 26.1 years (standard deviation (SD) 9.8), and 70.6% were male. With the exception of four patients with sickle/β-thalassaemia, all the patients had SCD (haemoglobin SS). The co-inheritance of a single 3.7 kb α-globin deletion was found in 42.3% of cases (n=11). The Bantu haplotype was the most observed (65.4% of chromosomes). Most HbF-promoting SNPs were not associated with variable levels of haematological indices.

Conclusions. There is an increasing burden of adult SCD patients at GSH. National health and academic institutions need to adapt policies and healthcare professional training accordingly.