Anemia and leucopenia on CBC. Hypoproteinemia. Elevated liver enzymes. Myeloid metaplasia on BMAT. Biopsy of the right vastus lateralis showed myositis. 15 weeks after HSCT muscle biopsy showed no necrosis and inflammation. CK and myoglobin were raised. A mutation in the RAB27A gene. The gene discussed is MB; the disease is anemia.