MYH9-related disease with a normal platelet count

Area of Science:

• Nephrology
• Hematology
• Genetics

Background:

• MYH9-related disease (MYH9-RD) typically involves macrothrombocytopenia, kidney failure, and hearing loss.
• Diagnosis of MYH9-RD is often based on characteristic clinical and hematological findings.

Purpose of the Study:

• To report a unique case of MYH9-RD presenting with normal platelet count.
• To highlight the diagnostic challenges and findings in a patient with MYH9-RD and proteinuria.

Main Methods:

• Case report of a 13-year-old boy with proteinuria and hematuria.
• Kidney biopsy with light and electron microscopy.
• Genetic analysis for MYH9 gene variant.
• Peripheral blood smear examination.

Main Results:

• Kidney biopsy revealed glomerular basement membrane abnormalities, initially suggesting Alport syndrome.
• Genetic testing identified a de novo MYH9 gene variant.
• Peripheral blood smear showed giant platelets and leukocyte inclusion bodies, confirming MYH9-RD.
• The patient had normal platelet counts throughout.

Conclusions:

• MYH9-RD can occur in the absence of thrombocytopenia.
• Glomerular basement membrane abnormalities in MYH9-RD may resemble those seen in Alport syndrome.
• Peripheral blood smear examination is crucial for diagnosing MYH9-RD, even with normal platelet counts and renal symptoms.