COMBINED ANKYRIN AND SPECTRIN DEFICIENCY IN HEREDITARY SPHEROCYTOSIS

Hereditary spherocytosis is characterized by a reduced spectrin conten t of the erythrocytes. However, the underlying primary defect remains unclear in the majority of cases. Genetic studies have revealed a link age to the gene for ankyrin in some families. By means of ELISA we mea sured the ankyrin, spectrin, and band-3 contents in erythrocytes of 45 patients with typical spherocytosis. They were classified as having m ild or moderate spherocytosis, according to clinical severity. Sixteen patients with mild spherocytosis showed slight reductions of ankyrin and spectrin contents. In contrast, 29 patients with moderate spherocy tosis exhibited a clear reduction of both ankyrin and spectrin to abou t 60% of normal. Band 3 and lipid phosphorus, as measures for membrane surface area, were only slightly reduced to 85%. Our results, togethe r with the molecular genetic data indicating the linkage between spher ocytosis and the gene for ankyrin, suggest an ankyrin defect or defici ency as the primary lesion in most cases of spherocytosis.