May-Hegglin anomaly associated nephropathy: Case series

May-Hegglin anomaly (MHA) is a rare autosomal dominant disease associated with a mutation in the MYH-9 gene. It is characterized by macrothrombocytopenia and neutrophils with abnormal cytoplasmic inclusions. Clinical features of this disease include hearing loss, early cataracts, and renal failure. We present two interesting cases of renal injury attributed to MHA. The first is a 52-year-old Hispanic female with MHA-associated nephropathy and thrombocytopenia complicated by Stage 3 chronic kidney disease (CKD) and hypothyroidism. She was found to have a pathogenic MYH-9 heterozygous mutation with associated clinical characteristics. Due to her thrombocytopenia from MHA, patient is not a candidate for kidney biopsy. She has been treated with SGLT-2 inhibitors, Angiotensin Receptor Blockers (ARBs) for managing her Stage 3b CKD and Synthroid^® for hypothyroidism. Despite these treatments, she continues to have low platelet counts, proteinuria, and progressive CKD. Our second case highlights a 39-year-old white female with MHA associated with focal segmental glomerulosclerosis diagnosed at the age of 15 on renal biopsy. She also has thrombocytopenia and mixed connective tissue disease with rheumatoid arthritis and systemic lupus erythematosus clinical characteristics. She is currently on a regimen of methotrexate, Xeljanz, and IVIG for her rheumatological diseases. Her kidney function has remained stable on Angiotensin Converting Enzyme Inhibitors (ACEi) with hydrochlorothiazide and as needed loop diuretics for edema. These cases illustrate the challenges of diagnosing and managing renal complications associated with MHA due to the MYH-9 gene mutation. Chronic thrombocytopenia in both patients restricts the use of invasive diagnostic procedures, such as biopsies, which are critical for confirming the relationship between nephropathy and MHA, and for guiding further treatment. As such, these cases stress the importance of genetic testing as a key tool in diagnosis and emphasize the difficulties in managing patients with suspected MHA-associated nephropathy and thrombocytopenia.