Case studies on haemoglobin S heterozygotes with severe clinical manifestations

Generally, individuals who are heterozygous to haemoglobin S (Hb AS) are asymptomatic and do not present any haematological or clinical manifestations. However, other associated genetic abnormalities may influence the presentation in Hb AS cases. This study was conducted on twenty children heterozygous for HB S who presented clinical manifestations similar to those of sickle cell anaemia. All these children had anaemia associated with several red cell morphological abnormalities. The white blood cell counts were elevated in all patients and differential count studies showed a substantial increase in lymphocytes and polymorphonuclear leucocytes in the majority of the cases. Forty-five per cent of the patients had associated alpha-thalassaemia, 60 per cent had beta-thalassaemia, 30 per cent had G-6-PD deficiency and 10 per cent had partial glutathione reductase deficiency. Pyruvate kinase activity was normal in all cases. Riboflavin deficiency was encountered in 30 per cent of the patients and iron deficiency in 15 per cent of these Hb S heterozygotes. The major clinical findings were splenomegaly, hepatomegaly, and vaso-occlusive crisis. The majority of the patients had received blood transfusions. The hand and foot syndrome was identified in three (15 per cent) of the patients. The haematological and clinical findings in these twenty Hb S heterozygotes are presented in this paper and the possible causes for these abnormalities are discussed.