Myocardial infarction in a newborn heterozygous for the MTHFR C677T mutation.

Neonatal myocardial infarction secondary to congenital heart disease, anomalous coronary artery anatomy, thromboembolism, coagulopathy, birth asphyxia, and unknown causes has been previously reported. We now report an infant who suffered a massive myocardial infarction during birth, requiring extensive resuscitation and aggressive management. A thrombus, the origin of which was not detected on autopsy, was found occluding the proximal left coronary artery several hours after birth. Genetic studies revealed a single copy variant of the MTHFR C677T mutation that we speculate may have predisposed the infant to coronary thrombosis.