Spherocytosis is one of the haemolytic diseases that is genetically determined. Depending on the type of mutation, it can be inherited in two ways - autosomal recessive or autosomal dominant. The disease was first reported in the early 20th century, when Oskar Minkowski and Anatole Marie Emile Chauffard described the results of their scientific observations. Congenital spherocytosis affects 1 child in every 5,000 healthy births. The cause of the disease is a genetic mutation that leads to the formation of an abnormal form of the protein spectrin or ankyrin. These proteins play an important role in the normal function of the erythrocyte membrane. Spectrin and ankrin provide the erythrocyte membrane with remarkable mechanical strength and flexibility. Mutation in the gene encoding ankyrin (ANK cells 1), spectrin alpha (ISAT1) and spectrin beta (SPTB) causes changes in the permeability and strength of the erythrocyte-building cell membrane. It is estimated that nearly 45 per cent of congenital spherocytosis cases are caused by mutations in the gene encoding ankyrin, 28 per cent by spectrin. As a result of abnormalities in the number of cell membrane-building proteins, erythrocytes lose their characteristic 'biconcave disk' shape, forming spherocytes. What is the risk of this? Spherocytes undergo haemolysis, i.e. break down much faster than erythrocytes.

The most characteristic clinical signs of congenital spherocytosis, in addition to changes within the red cells, include :

• anaemia in childhood,
• jaundice (mainly in childhood),
• characteristic towering skull,
• splenomegaly - enlargement of the spleen,
• syndactylia - fusion of two or more fingers or toes,
• polydactyly - presence of an extra finger,
• brachydactyly - shortening of fingers or toes,
• hypertelorism - enlargement of the distance between the eyeballs.

Diagnostic tests to assess erythrocyte membrane abnormalities

Among the most commonly used screening tests to confirm or exclude congenital spherocytosis is the erythrocyte osmotic resistance test. The test assesses the behaviour of erythrocytes isolated from blood in hypotonic NaCl solution. In cases of spherocytosis, osmotic resistance is reduced. However, the test with NaCl solution is unreliable in young children and infants due to the physiologically proven increased osmotic resistance during this period of life. A new method used to assess erythrocyte membranes is the EMA binding test, a cytometric analysis of erythrocyte membrane proteins. The test involves taking a blood sample and then assessing erythrocyte parameters using a flow cytometer. The method demonstrates high sensitivity - reaching nearly 93%.

Treatment of congenital spherocytosis

The clinical symptoms of congenital spherocytosis already appear in the first weeks of a child's life as severe anaemia, often accompanied by jaundice. In this case, it is often necessary to administer a red blood cell concentrate transfusion (in the case of severe spherocytosis) or subcutaneous erythropoietin injections. In severe spherocytosis, a common form of treatment is splenectomy, i.e. removal of the spleen. Depending on the age of the child, the spleen is removed either completely or partially. Children who suffer from moderate to severe spherocytosis are often recommended chronic folic acid supplementation.