Platelet and Red Blood Cell Indices in Harris Platelet Syndrome.

Inherited giant platelet disorders are a group of rare disorders characterized by thrombocytopenia, giant platelets and variable bleeding symptoms. Naina et al., described a new giant platelet disorder called Harris Platelet Syndrome (HPS), the most common inherited giant platelet disorder occurring in up to one third of blood donors from north eastern part of Indian subcontinent. HPS is characterized by an autosomal dominant mode of inheritance with normal to severe thrombocytopenia (less than 50x10⁹/L), giant platelets (mean platelet volume more than 10fL) and absent bleeding symptoms with normal platelet aggregation studies. Occasionally abnormalities in red blood cell morphology have been associated with certain giant platelet disorders such as stomatocytosis in Mediterranean Macrothrmboctopenia, dyserythropoiesis in GATA 1 associated macrothrombocytopenia and thalassemia, in X Linked Thrombocytopenia Thalassemia (XLTT).

This study was undertaken to analyze the platelet and red blood cell indices in blood donors with Harris Platelet syndrome. A total of 203 blood donors were included in this study, 101 blood donors from northeaster part of India with MPV more than 12fl (normal 7–10fl) and 102 blood donors from southern part of India. Before blood donation, all donors were questioned about a history of bleeding conditions, in either themselves or their relatives. Blood samples were collected in ethylenediaminetetraacetic acid (EDTA). Automated platelet counts were performed using a Coulter STKS (Coulter, Hialeah, Florida) within 2 hours of collection.

Peripheral blood smears were examined to confirm thrombocytopenia, giant platelets and red blood cell morphology. There was a significant difference between platelet count (Mean ±SD) 136± 40 Vs 262 ± 53 in southern India (p<0.000). Thirty three donors with HPS had a normal platelet count with MPV more than 12fL. MPV was 13.6±0.13 (range 12 to21.9fL) in donors with HPS and 7.3 ±0.6 (range 6–9.2fl) in southern Indian blood donors. The platelet distribution width (PDW) was 17.4±0.8 in donors with HPS and was 16.38±0.5 in southern India blood donors(p<0.000). Though there was a significant difference between hemoglobin, 13.8 ± 1.0 vs and 14.7± 1.1 (P<0.00), there was no significant difference between RDW, MCV, MCH, MCHC. Peripheral blood smear did not show any obvious red blood cell abnormality, but showed giant platelets and thrombocytopenia.

Harris platelet syndrome is associated with normal to severe thrombocytopenia, giant platelets and significant platelet anisocytosis. There was no associated red blood cell abnormalities observed with HPS.