We identified 28 causal rare MYH9 variants in 50 patients (44 index cases), 20 with a diagnosis of MYH9‐RD based on the presence of macrothrombocytopenia, Döhle‐like bodies and an extra‐hematological phenotype in some cases but without genetic confirmation, 11 with suspected but unconfirmed MYH9‐RD, and 19 in whom MYH9‐RD was not previously suspected despite an expert evaluation of their clinical and laboratory data. Here, MYH9 is linked to Macrothrombocytopenia.