[Renal diseases related to MYH9 disorders]

Mutations in MYH9 gene encoding the nonmuscle myosin heavy chain IIA (NMMHC-IIA) are related to a number of rare autosomal-dominant disorders which has been known as May-Hegglin disease, Sebastian syndrome, Fechtner syndrome and Epstein syndrome. Their common clinical features are congenital macrothrombocytopaenia and polymorphonuclear inclusion bodies, in addition to a variable risk of developing proteinuria, chronic kidney disease progressing toward end stage, sensorineural deafness and presenile cataracts. The term MYH9 related disease (MYH9-RD) describes the variable expression of a single illness encompassing all previously mentioned hereditary disorders. Renal involvement in MYH9- RD has been observed in 30% of patients. Mutant MYH9 protein, expressed in podocytes, mesangial and tubular cells, plays a main role in foot process effacement and in development of nephropathy. Interestingly, the MYH9 gene is currently under investigation also for his possible contribution to many other non-hereditary glomerulopathies such as focal global glomerulosclerosis (hypertensive nephrosclerosis), idiopathic focal segmental glomerulosclerosis, C1q nephropathy and HIV-associated nephropathy. In this review we are aimed to describe renal diseases related to MYH9 disorders, from the hereditary disease to the acquired disorders, in which MYH9-gene acts as a "renal failure susceptibility gene".