MYH9-related disorders: a rare cause of neonatal thrombocytopaenia

Myosin heavy chain 9-related disorders (MYH9RD) are a genetic condition characterised by large platelets and thrombocytopaenia. The May-Hegglin anomaly (MHA), an uncommon condition with a potential risk of bleeding complications once thought to be separate, is now known to be part of MYH9RD.There are very limited data on the clinical course and neonatal/paediatric outcome in children with MHA. We present the case of a newborn with a normal physical examination whose mother had MHA. Peripheral blood examination revealed a platelet count of 16×10⁹/L with giant platelets and neutrophils containing Döhle bodies. Neonatal brain ultrasound examination showed no haemorrhage. The infant received three platelet transfusions during the first 29 days of life, remaining asymptomatic. The genetic molecular test was positive for MYH9RD. It is important to identify at-risk infants with this condition and to initiate therapy to prevent related complications, if needed, in a multidisciplinary team approach.