ACTA1 and cyclic hematopoiesis: In our cohort only one infant with the neuromuscular disorder nemaline myopathy (mutation ACTA1-gene) was found, while Friedrich ataxia was the main cause of neuromuscular disease in the cohort with children of Colan et al.11 The relatively high incidences of metabolic disease and malformation syndromes and low incidence of neuromuscular disorders in our cohort of infants might be explained by the fact that metabolic or syndromic CH usually presents in infancy or early childhood, whereas those with neuromuscular disorders are more frequently diagnosed in adolescence13.