Increased thrombosis incidence in a family with an inherited protein S deficiency and a high oxygen affinity hemoglobin variant.

Inherited protein S deficiency and the presence of a rare high oxygen affinity hemoglobin variant: Hb Rainier [beta 145 (HC2) Tyr-->Cys] were found in a family. Among 16 studied members, nine were found as carriers of protein S deficiency (type I with decrease of total, free, and activity levels). Six subjects carried the high-affinity hemoglobin variant, which displayed an increase of blood viscosity. Four members combined both abnormalities. Three had thrombotic accidents before the age of 30. We suggest the combination of protein S deficiency and the presence of this hemoglobin variant can lead to a severe primary hypercoagulable state with pathological consequences compared to each genetic defect alone.