MYH9-related disease is a genetic disorder of autosomal dominant inheritance caused by mutations in the MYH9 gene on chromosome 22q12, which encodes the non-muscle myosin heavy chain IIA (NMMHC-IIA). The disorder is characterised by congenital thrombocytopaenia, giant platelets, hearing impairment, nephropathy, and early cataract. The frequency of MYH9-related disease is unknown, as the condition is underdiagnosed, but it has been estimated to occur in 1 in 20,000–25,000 individuals. The case report concerns a 28-year-old female who was initially diagnosed with Bernard–Soulier syndrome, and it took several years to find the correct diagnosis. The diagnosis of MYH9-related disease is often delayed. It should be considered in any patient with a variable degree of glomerular involvement associated with a low or slightly decreased platelet count and/or hearing loss, cataract, and liver dysfunction.