Key Clinical MessageGlucose‐6‐phosphate (G6PD) deficiency is the most common human enzyme defect, often presenting with neonatal jaundice and/or acute hemolytic anemia, triggered by oxidizing agents. G6PD deficiency is an X‐linked, hereditary disease, mainly affecting men, but should also be considered in females with an oxidative hemolysis.

A previously healthy 10-month-old boy was referred to our hospital because of coarse facial features that were suggestive of lysosomal storage disease. Apart from noisy respiration, there was no medical history. Elevated levels of urinary glycosaminoglycans and complete deficiency of leukocyte α-l-iduronidase indicated severe mucopolysaccharidosis type I. A chest radiograph revealed a markedly enlarged heart, and echocardiography revealed hypertrophic cardiomyopathy. While hematopoietic stem cell transplantation was being planned, progressive cardiac failure developed with a striking hypokinesia of the left-ventricle free wall. In combination with ischemic changes on the electrocardiogram, this was suggestive of coronary artery disease. Results of coronary echo Doppler interrogation were inconclusive, and intravascular ultrasound in this little infant was not feasible. Despite the patient's small size, a successful selective coronary angiography was performed and revealed diffuse narrowing of the left coronary artery with collateral flow from the right coronary artery. Enzyme-replacement therapy was started immediately in an attempt to improve myocardial performance. Evaluation after 3 months, however, revealed complete obliteration of the left coronary main stem with diffuse hypokinesia/akinesia of the left ventricle. At the age of 13 months the boy died of terminal cardiac failure. This case report illustrates the importance of considering early development of coronary artery disease in children with severe mucopolysaccharidosis type I and cardiomyopathy.

Neonatal neutropenia is regularly seen with variable etiology. We describe a breastfed infant with maternal medication use as a probable cause of neonatal neutropenia. An 8 days old exclusively breastfed female infant of Arab-Berber descent was referred to our hospital because of an infection of the umbilicus. Complete blood count showed a picture of severe isolated neutropenia. After initiating intravenous antibiotic treatment, the infection quickly resolved, but the isolated neutropenia persisted. Bone marrow aspiration indicated severe congenital neutropenia. The mother was known to have Crohn’s disease, treated with methylprednisolone and adalimumab up to 3 months before delivery, and latent tuberculosis, for which she used isoniazid postnatally. Breast-feeding was terminated and filgrastim was started, with an increase of the neutrophilic count. After several weeks, filgrastim could be terminated. Bone marrow and complete blood count were repeated and were completely normal. This case report describes a very young breastfed female infant with severe neutropenia, causing an infection, in which maternal adalimumab use could not be excluded as a possible cause. Maternal isoniazid use is highly unlikely.