Successful Renal Transplantation in MYH9-Related Disorder With Severe Macrothrombocytopenia: First Report in Korea

Successful administration of eltrombopag in preparation for peritoneal dialysis catheter placement in a girl with MYH9-related disease

MYH9-related disease is an autosomal dominant disorder characterized by macrothrombocytopenia, nephropathy, inclusion bodies in leukocytes, sensorineural hearing loss, and cataract. Severe cases require kidney replacement therapy in the patient's second decade of life; thrombocytopenia constitutes a major risk factor for hemorrhagic complications during dialysis initiation or kidney transplantation. Prophylactic platelet transfusion prior to surgery is commonly administered to affected patients in these cases. However, transfusion in such patients has limitations other than the general risk of allergic reactions and blood-borne infections; it may also trigger alloimmunization, leading to platelet transfusion resistance or the development of anti-donor antibodies in potential kidney transplant recipients. Here, we describe prophylactic administration of eltrombopag, an oral thrombopoietin receptor agonist, prior to laparoscopic peritoneal dialysis catheter placement in a 15-year-old girl with MYH9-related disease. Her platelet count was approximately 30 × 103/μL at baseline; it increased to 61 × 103/μL on the day before surgery, thereby avoiding the need for platelet transfusions. There were no major bleeding or adverse events associated with eltrombopag administration. Thus, eltrombopag may be a safe and effective alternative to prophylactic platelet transfusions in patients with MYH9-related disease.

Anesthetic Management of Living-Donor Renal Transplantation in a Patient With Epstein Syndrome Using Rotational Thromboelastometry: A Case Report

Epstein syndrome is a myosin heavy chain 9 (MYH9)-related disorder characterized by hearing loss and macrothrombocytopenia with renal failure, which usually requires platelet transfusion during surgery. We report the case of a 22-year-old man who underwent living-donor renal transplantation without platelet transfusion using rotational thromboelastometry (ROTEM) monitoring. His intraoperative laboratory coagulation findings were a platelet count of 28–31 × 10⁹/L based on microscopy and fibrinogen of 256 mg/dL. However, his extrinsic pathway evaluations by ROTEM were normal. The estimated blood loss during the operation was 150 mL, and the patient showed no bleeding complications without platelet transfusion.

Epstein Syndrome

Epstein syndrome is characterized by sensorineural hearing impairment, macro- thrombocytopenia without neutrophil inclusion bodies, and hereditary nephritis which can progress to end-stage renal disease (ESRD) in adolescence. The prognosis of Epstein's syndrome depends on the severity of the hematological disorders and renal involvement that can lead to ESRD at an early age. Thrombocytopenia in Epstein syndrome is not an absolute contraindication for major surgical procedures like arteriovenous fistula formation or kidney transplantation. There are no set guidelines for preoperative prophylaxis in a patient with this pathology.

Familial macro thrombocytopenia: role of genetics where morphology fails

: Myosin heavy chain 9 (MYH9)-related disorders are rare inherited platelet disorders that are accompanied by a wide variety of systemic abnormalities. The persistent thrombocytopenia is usually asymptomatic and these patients are often misdiagnosed and treated as immune thrombocytopenia. MYH9 gene has been studied in association with solid organ malignancies. We report a young girl with family history of thrombocytopenia and hearing loss who presented with kidney dysfunction and later developed acute lymphoblastic leukemia. She lacked the characteristic inclusion bodies in her blood granulocytes, however a diagnosis of MYH9-related Epstein syndrome was confirmed on genetic testing. In the background of known causal association of MYH9 gene in solid organ malignancies, the role of MYH9 gene variant in malignant transformation in the index case remains conjectural.

MYH9-related disorders display heterogeneous kidney involvement and outcome

Background

MYH9-related diseases (MYH9-RD) are autosomal dominant disorders caused by mutations of the MYH9 gene encoding the non-muscle myosin heavy chain IIA. They are characterized by congenital thrombocytopenia, giant platelets and leucocyte inclusions. Hearing impairment, pre-senile cataract and nephropathy can also occur. We aimed to evaluate renal involvement and outcome in MYH9-RD patients followed-up by nephrologists.

Methods

We conducted a retrospective multicentre observational study of 13 patients among 9 families with MYH9 mutation diagnosed by genetic testing and immunofluorescence assay referred to nephrologists.

Results

At initial referral, median age was 30 (range 14–76) years. Median estimated glomerular filtration rate was 66 mL/min/1.73 m² (0–141) and two patients had already end-stage renal disease (ESRD). Renal presentation associated proteinuria (n = 12), haematuria (n = 6) and hypertension (n = 6). Three patients developed a rapid onset ESRD whereas five others had a relatively stable kidney function over a 3-year median follow-up (1–34). Extra-renal features varied widely, with hearing impairment in six patients, cataract in two and mild liver dysfunction in seven. Thrombocytopenia existed at referral in 11 patients. Time to diagnosis varied from 0 to 29 years (median 3 years). Initial diagnoses such as idiopathic thrombocytopenic purpura (n = 4) and focal segmental glomerulosclerosis (n = 1) led to corticosteroid administration (n = 4), intravenous immunoglobulins (n = 3), cyclophosphamide (n = 1) and splenectomy (n = 1).

Conclusions

Renal involvement and outcome in MYH9-RD are heterogeneous. The diagnosis is often delayed and misdiagnoses can lead to unnecessary treatments. MYH9-RD should be considered in any patient with glomerular involvement associated with a low or slightly decreased platelet count and/or hearing loss and liver dysfunction.

Macrothrombocytopenia With Döhle Body-Like Granulocyte Inclusions: A Case Report of May-Hegglin Anomaly in a 33-Year-Old White Woman With an Update on the Molecular Findings of MYH9-Related Disease

A 33-year-old white woman arrived at the hospital to undergo a hysterectomy due to uterine fibroids. Blood smear review identified macrothrombocytopenia and Döhle body-like cytoplasmic leukocyte inclusions. Genetic testing identified a mutation in exon 39 of the myosin heavy chain gene (MHY9; OMIM 160775), which confirmed the diagnosis of May-Hegglin anomaly. May-Hegglin anomaly is one of a spectrum of MYH9 disorders that also includes Sebastian, Epstein, and Fechtner syndromes. Herein, we describe the clinical and laboratory presentation of a patient with May-Hegglin anomaly and provide an update on the molecular findings and a discussion of the genotypic-phenotypic correlations in this potentially underdiagnosed disorder.

A case of cochlear implantation in a patient with Epstein syndrome

Epstein syndrome is a rare autosomal dominant platelet disorder characterized by thrombocytopenia, giant platelets, and sensorineural hearing loss. It is included among four overlapping syndromes, the others being May-Hegglin anomaly, Fechtner syndrome, and Sebastian syndrome. It is now established that all four disorders are caused by mutations in the MYH9 gene. We report the case of a patient with Epstein syndrome in whom bilateral profound hearing impairment developed and cochlear implantation was carried out. A cochlear implant was successfully used with a speech discrimination score of 100% on a Japanese sentence recognition test. This report offers the second description of the performance of a cochlear implant in a patient with Epstein syndrome. This case study may offer hope for patients and their family members with this kind of mutation.

Life without double-headed non-muscle myosin II motor proteins

Non-muscle myosin II motor proteins (myosin IIA, myosin IIB, and myosin IIC) belong to a class of molecular motor proteins that are known to transduce cellular free-energy into biological work more efficiently than man-made combustion engines. Nature has given a single myosin II motor protein for lower eukaryotes and multiple for mammals but none for plants in order to provide impetus for their life. These specialized nanomachines drive cellular activities necessary for embryogenesis, organogenesis, and immunity. However, these multifunctional myosin II motor proteins are believed to go awry due to unknown reasons and contribute for the onset and progression of many autosomal-dominant disorders, cataract, deafness, infertility, cancer, kidney, neuronal, and inflammatory diseases. Many pathogens like HIV, Dengue, hepatitis C, and Lymphoma viruses as well as Salmonella and Mycobacteria are now known to take hostage of these dedicated myosin II motor proteins for their efficient pathogenesis. Even after four decades since their discovery, we still have a limited knowledge of how these motor proteins drive cell migration and cytokinesis. We need to enrich our current knowledge on these fundamental cellular processes and develop novel therapeutic strategies to fix mutated myosin II motor proteins in pathological conditions. This is the time to think how to relieve the hijacked myosins from pathogens in order to provide a renewed impetus for patients' life. Understanding how to steer these molecular motors in proliferating and differentiating stem cells will improve stem cell based-therapeutics development. Given the plethora of cellular activities non-muscle myosin motor proteins are involved in, their importance is apparent for human life.