HEREDITARY XEROCYTOSIS - A REPORT OF 6 UNRELATED SPANISH FAMILIES WITH LEAKY RED-CELL SYNDROME AND INCREASED HEAT-STABILITY OF THE ERYTHROCYTE-MEMBRANE

Hereditary xerocytosis (HX) is a rare haemolytic disease due to dehydr ated red blood cells (RBCs), A unique feature of this syndrome is that affected members often show normal or near normal haemoglobin levels despite clinical and laboratory evidence of mild to moderate haemolysi s. The diagnostic clue is the association of markedly increased RBC Na ++K+ fluxes with low total cation (Na++K+) content, 11 patients of six unrelated families of Spanish origin with HX have been studied from c linical, genetical and biological points of view, In addition, we have investigated the sensitivity of RBC membrane to heat at three differe nt incubation times (15, 30 and 60 min) and two different temperature values (46 degrees C and 49 degrees C), Under these conditions control RBCs (50 normal subjects) exhibited at 49 degrees C and 30 min a maxi mum of 30% fragmented RBCs, This value increased to 80% after 60 min o f incubation. In contrast, patients with HX showed significantly lower percentages of fragmented RBCs at both 30 and 60 min of incubation (m aximum 10% and 30%, respectively), In an attempt to determine if incre ased heat stability was unique to HX RBCs, several other congenital me mbranopathies with haemolytic anaemia were also studied. The degree of fragmentation, except in one case of HPP (which was strongly increase d), did not differ from the control group. Electrophoretic studies of membrane proteins performed in RBCs of all the patients with HX did no t explain any qualitative nor quantitative abnormality. In addition to its physiopathological interest, study of RBC heat stability, togethe r with other haematological parameters (increased MCHC and decreased R BC osmotic fragility), may be useful for HX diagnosis, especially in l aboratories which are not equipped to evaluate RBC membrane permeabili ty.