- Key words: hereditary haemolitic anaemia, stomatocytes, Caenorhabditis elegans.
- Page(s) : 501-8
- Published in: 1998
The term of hereditary stomatocytosis was initially coined in 1961 on the basis of the red cell shape in a particular case of hereditary haemolytic anaemia. The cells were called stomatocytes. They presented with a straight slit that replaced the circular depression observed in normal erythrocytes. Gradually, however, a confusion settled between stomatocytes and stomatocytosis. As a matter of fact, all hereditary haemolytic anaemias with stomatocytes do not fit the case first described. Today, the initial entity has shattered into a number of distinct disorders. In the first part of this review, we will present an updated classification of hereditary haemolytic anaemias with stomatocytes. One of them is hereditary stomatocytosis with overhydrated erythrocytes. It is associated with the absence or the pronounced reduction of a transmembrane and ubiquitous protein, stomatin, encoded by the EPB72 gene. Its function is unknown. Recent findings suggest, however, that the absence of stomatin is probably not the primary cause of the disease. Other hereditary haemolytic anaemias with stomatocytes will be described : first and foremost, hereditary stomatocytsis with dehydrated erythrocytes (also designated hereditary xerocytosis), whose presentation varies depending on the extent of its manifestations, the stomatocytosis recorded in the Rhnull syndrome and, finally, the stomatocytosis associated with miscellaneous disorders. Most conditions, if not all, are thought to stem from mutations affecting ion channels or transporters. Virtually no indices being available at the protein level, with the exception of stomatin, the search for candidate genes is going on based on linkage analysis. In the second part, we will back up to stomatin and its gene. No homologous gene is known in the human genome. Recently, homologies were uncovered between the EPB72 gene, and genes mec-2 and unc-24 of the primitive nematode Caenorhabditis elegans. The mec-2 gene encodes a protein related to transport in sensory neurones. On the other hand, relatedness to a transport is not established as regards the unc-24 gene product in motoneurones. Mutations are known in both genes.