Testing for haemoglobinopathies in Johannesburg, South Africa: a 30-year review.

BACKGROUND

Haemoglobinopathies are seen mostly in regions where malaria occurs or has occurred, but population migration has resulted in affected individuals being identified in many countries globally. The first molecular genetics services for diagnostic testing and prenatal diagnosis were established, both worldwide and in South Africa (SA), for haemoglobinopathies.

OBJECTIVE

To analyse the diagnostic service offered by the Division of Human Genetics, National Health Laboratory Service and University of the Witwatersrand, from 1983 to 2012.

METHODS

A retrospective file analysis (N=1 249) was performed for all individuals who had molecular genetic testing for α-thalassaemia, β-thalassaemia and sickle cell anaemia to examine indications for testing, population origins of patients and molecular genetics findings.

RESULTS

The α-thalassaemia testing was requested predominantly to explain microcytic hypochromic haematological indices. Five α-globin deletions were identified, the most common being the -α3.7, in individuals of different ethnicities. For β-thalassaemia and sickle cell anaemia, most testing was performed for prenatal diagnosis purposes. For sickle cell anaemia, most prenatal tests were requested by African families. The β-thalassaemia families were mostly of Indian or Mediterranean origin. The most common mutation identified in all Indian groups was IVS1 nt5 (G>C) (c.92+5G>C) and in individuals from the Mediterranean, IVS1 nt110 (G>A) (c.93-21G>A).

CONCLUSION

The molecular genetics service for haemoglobinopathies in SA is comprehensive and specific to the needs of local ethnic groups. Clinically significant haemoglobinopathies occur at significant frequencies in specific high-risk ethnic groups. Appropriate screening programmes should be initiated so that genetic counselling and reproductive options can be offered.