Familial pseudohyperkalemia maps to the same locus as dehydrated hereditary stomatocytosis (hereditary xerocytosis)

Familiar pseudohyperkalemia is a "leaky red blood cell" condition in which the cells show a temperature-dependent loss of potassium (K) from red blood cells when stored at room temperature, manifesting as apparent hyperkalemi a. The red blood cells show a reduced lifespan in vivo but there is no fran k hemolysis. Studies of cation content and transport show a marginal increa se in permeability at 37 degrees C and a degree of cellular dehydration, qu alitatively similar to the changes seen in dehydrated hereditary stomatocyt osis (hereditary xerocytosis). Physiological studies have shown that the pa ssive leak to K has an abnormal temperature dependence, such that the leak is less sensitive to temperature than that in normal cells. We performed ge netic mapping on the original family and found that the condition in this k indred maps to the same locus (16q23-ter) that we have previously identifie d for an Irish family with dehydrated hereditary stomatocytosis, which does not show the same temperature effects. (C) 1999 by The American Society of Hematology.