GENETIC COMPOUNDS - HB-S, THALASSEMIAS AND ENZYMOPATHIES - SPECTRUM OF INTERACTIONS

In areas with high occurence of the red cell genetic abnormalities, i. e. sickle cell gene, alpha- and beta-thalassaemias, and glucose-6-phos phate dehgdrogenase deficiency, various genes frequently co-exist in t he same population. Co-inheritance of two or more abnormal genes in th e same individual is frequently encountered, particularly in certain ' closed' tribes in Arabia in which consanguinity is the norm. Such gene ric interactions modify the clinical presentations of the disease stat e. During our studies, we encountered a large number of individuals wh o were carriers of two or more abnormal genes. The most frequent genet ic compounds were double heterozygous HbS-beta degrees-thalassaemia an d HbS-beta(+)-thalassaemia with associated alpha-thalassaemia or G-6-P D deficiency. Clinical history, and assessment, as well as blood analy sis for haematological, biochemical, and molecular pathology determina nts were carried out. The patients were classified into subgroups, bas ed on the genetic findings. The clinical, haematological and biochemic al data were assessed separately for each group. Sickle cell anaemia ( Hb SS) cases, without any other abnormal gene, were used as a referenc e group. The results showed severe anaemia in patients with HbS/beta d egrees-thalassaemia and associated alpha-thalassaemia and/or G-6-PD de ficiency. Patients with Hbs/beta degrees-thalassaemia exhibited featur es similar to that of the sickle cell anaemia. While sickle cell anaem ia patients with alpha-thalassaemia and G-6-PD deficiency exhibited a milder presentation. This paper presents various forms of genetic asso ciations, their influence on the clinical presentation and the laborat ory parameter data, and discusses the implications of the findings.