An inherited, mild, non-hemolytic subtype of hereditary stomatocytosis that is associated with a temperature-dependent anomaly in red cell membrane permeability to potassium that leads to high in vitro potassium levels in samples stored below 37°C. FP is not associated with additional hematological abnormalities, although affected individuals may show some mild abnormalities like macrocytosis. The disease is familial pseudohyperkalemia (MONDO_0012204, a Monarch Disease Ontology entry). Also known as: PSHK2, pseudohyperkalemia, familial, 2, due to red cell leak.