DIAPH1 Mutation as a Novel Cause of Autosomal Dominant Macrothrombocytopenia and Hearing Loss

Macrothrombocytopenia (MTP) is a group of rare disorders characterized by giant platelets, thrombocytopenia, and variable association with abnormal bleeding. Inherited MTP are frequently misdiagnosed as immune thrombocytopenia. Associated second-organ manifestation can help narrow down syndromic MTPs. We describe a case of autosomal dominant sensorineural hearing loss and MTP caused by a gain of function mutation in DIAPH1. This mutation causes altered megarkaryopoiesis and platelet cytoskeletal deregulation. Although hearing loss and MTP were likely progressive, clinically significant bleeding was not observed. DIAPH1-related MTP can be distinguished clinically from MYH9 mutation by the absence of cataracts and glomerular disease.

Anesthetic management without perioperative platelet transfusion for cervical laminectomy and laminoplasty in a case of May-Hegglin anomaly

May-Hegglin anomaly (MHA) is an inherited autosomal dominant disorder characterized by giant platelets and inclusion bodies in granulocytes, and thrombocytopenia. There is no consensus on the perioperative management of this disorder. We report a case involving a patient with MHA who was perioperatively managed without platelet transfusion for cervical laminectomy and laminoplasty. In our case, the platelet count was measured to be 0.6 × 10⁴/µL using an automatic blood cell counter. Peripheral blood smear and genetic test analyses were performed, leading to a definitive diagnosis of MHA. However, clot retraction, serotonin release, and platelet aggregation were normal. Total intravenous anesthesia with propofol and remifentanil, in combination with intermittent injection of fentanyl, was administered. The total blood loss volume was 300 mL, and perioperative course was uneventful. Visual platelet count and platelet function were preserved in this case, although platelet or red blood cell transfusion was not performed. No bleeding tendency was observed during perioperative management.

Bengal macrothrombocytopenia is not totally an innocuous condition

Inherited macrothrombocytopenia is a subgroup of thrombocytopenias, and is characterised by the presence of giant platelets and decreased platelet count with variable bleeding manifestations. Bengal macrothrombocytopenia is a newly described entity, previously called asymptomatic constitutional macrothrombocytopenia (ACMT), presented with variable bleeding tendencies; with mild to severe thrombocytopenia and macro-platelets in their peripheral blood smear and it is not totally an innocuous condition as described previously.

A diagnostic approach that may help to discriminate inherited thrombocytopenia from chronic immune thrombocytopenia in adult patients

Inherited thrombocytopenia (IT) is a heterogeneous group of rare diseases that are often confused with immune thrombocytopenia (ITP). The objective of this study was to supply clinicobiological elements that allow a distinction to be drawn between IT and chronic ITP. We then compared 23 adult patients with IT and 9 patients with chronic ITP. Our study revealed six discriminating criteria: (i) an age of discovery <34 years: positive predictive value (PPV) = 88.2% [63.6; 98.5], (ii) a family history of thrombocytopenia: PPV = 100.0% [82.4; 100.0], (iii) a personal history of bleeding: PPV = 100% [76.8; 100.0], (iv) a mean platelet volume >11 fL: PPV = 93.3% [68.1; 99.8], (v) an excess of giant platelets on blood smear: 100.0% [76.8; 100.0], and (vi) a percentage >44% of platelets with a surface area >4 µm(2) in electron microscopy: PPV = 83.3% [58.6; 96.4]. If at least three of these criteria were combined, it was possible to distinguish IT from chronic ITP with 91.3% [72.0; 98.9] sensitivity and PPV = 100.0% [66.4; 100.0] specificity. The secondary objective of this study was to assess the prevalence of potential IT diagnosis in patients with chronic thrombocytopenia of uncertain origin. Applying our diagnostic approach to a series of 20 cases allowed us to estimate that 40% of them could be suffering from IT. Finally, our diagnostic approach may help to correctly distinguish IT from chronic ITP, particularly in the context of macrothrombocytopenia.