The implementation of laboratory investigations for diagnosing pyruvate kinase deficiency at the Johannesburg Hospital

Abstract

ABSTRACT Pyruvate kinase is an essential enzyme in the anaerobic glycolytic pathway of the erythrocyte. The clinical presentation of this enzyme deficiency is due to the haemolytic process that results from the inability of erythrocytes to generate sufficient ATP. Although pyruvate kinase and glucose-6-phosphate dehydrogenase deficiencies comprise more than 90% of all reported red cell enzyme disorders worldwide, the epidemiology of the disease in South Africa is unknown and there is no assay for pyruvate kinase activity currently being used in South Africa. This report describes the implementation of screening and quantitative assays for pyruvate kinase activity in the Red Cell Membrane Unit at the University of the Witwatersrand Medical School / NHLS. The accuracy, precision and reproducibility of the assay were verified. Furthermore, a patient with pyruvate kinase deficiency was confirmed and found to have 15% of normal enzyme activity at 37oC. The genetic abnormality was identified as a homozygous G1529A point mutation in exon 11 of the pyruvate kinase gene and to the candidate’s knowledge is the first mutation described in a South African kindred. The patient’s mother was heterozygous for the G1529A mutation and demonstrated an enzyme activity of 58% of normal at 37oC.