T CHANG1, T DAVIDSON2
1The Wollongong Hospital, Wollongong, Australia, 2Prince of Wales Hospital, Randwick, Australia
Background: MYH9 gene encodes non-muscle-myosin-IIA (NMMHC-IIA) with expression in renal podocytes. MYH9 is increasingly recognised as a renal susceptibility gene. May-Hegglin anomaly (MHA) is a phenotype of MYH9-RD. We describe a case of MHA associated nephropathy, the first reported in Australia.
Case report: A 62-year-old woman was reviewed in renal clinic. Background includes hypothyroidism, 5 years hypertension and MHA diagnosed at age 28 during infertility investigation. She has teenage-onset deafness and pre-senile cataracts. Assessment revealed edema, 14kg weight gain, hypertension, proteinuria, microhaematuria and acute kidney injury. Her blood film showed Döhle Bodies and megathrombocytopenia without haemolysis. Desmopressin and platelets were given before 2 renal biopsies without complication. Biopsies were widely reviewed and concluded as unique showing glomerular basement membrane (GBM) abnormalities, podocytopathy and mesangiopathic glomerulopathy. Congo red and immunofluorescence were negative. Electron microscopy showed widespread GBM abnormalities: extreme thinning, marked podocyte effacement, unusual duplication separated by mesangial matrix but no fibrils or deposits.
Treatment was renin-angiotensin system (RAS) blockade. At 3 year follow up, she achieved marked proteinuria reduction and improvement of blood pressure and renal function.
Review of MYH-RD
MHA was described by May (1900) and Hegglin (1945). It is now grouped with similar syndromes (Sebastian, Fetchtner, Epstein syndromes) to be part of MYH9-RD involving chromosome 22. Phenotypes include megathrombocytopenia, progressive sensorineural hearing loss, nephropathy and presenile cataracts. It is an autosomal dominant disorder but sporadic cases exist. Under-reporting is likely with some cases first diagnosed as immune thrombocytopenic purpura and received futile steroid and/or splenectomy. Renal biopsies are infrequently performed. RAS blockade is effective for proteinuria. MYH9 gene is gaining significance in other non-hereditary glomerulopathies including focal global glomerulosclerosis, C1q and HIV-associated nephropathy.
Staff Specialist, The Wollongong Hospital