The integrity of the red cell membrane depends on molecular interactions between proteins and the phospholipid membrane: vertical interactions stabilize the membrane lipid bilayer; horizontal interactions provide resistance against shear stress. Hereditary spherocytosis—affects 1 in 25 000 individuals of northern European descent. There is typically a dominant family history, but the condition is genetically heterogeneous: combined spectrin and ankyrin deficiency is the most common defect observed, followed by band 3 deficiency, isolated spectrin deficiency, and protein 4.2 deficiency. These affect vertical membrane interactions with loss of surface area relative to red cell volume. Clinical features—the key clinical manifestations are anaemia and signs of persistent haemolysis, with jaundice and a marked propensity to gallstones. Complications and treatment—parvovirus B19 infection of erythropoietic precursors may cause acute aplastic crises. Megaloblastic anaemia due to folate deficiency occurs in response to increased requirements during growth and pregnancy, but is preventable with supplementation. Splenectomy can alleviate the anaemia in many patients and reduces the risk of gallstones. Hereditary elliptocytosis—occurs with a frequency of 1 in 2000 to 1 in 4000 worldwide, and is more frequent in parts of Africa. The inheritance is usually dominant, with defects in red cell proteins such as α- and β-spectrin causing disturbances in horizontal interactions in the erythrocyte membrane. Clinical features, diagnosis, and treatment—most patients are asymptomatic and are typically diagnosed incidentally during testing for unrelated conditions, but about 10% experience haemolysis, anaemia, splenomegaly, and intermittent jaundice. Diagnosis is based on the presence of elliptocytes on a peripheral blood smear. Treatment is rarely required. Other conditions include hereditary pyropoikilocytosis, South-East Asian (or Melanesian) ovalocytosis, stomatocytosis, and acanthocytosis.
Biosynthetic insulin effect on red cell membrane lipid peroxidation in patients with insulin-dependent diabetes
