In this Shortcast, Sophie Manoy summarises a newly reported case of holocarboxylase synthetase deficiency presenting with neonatal cholestatic liver disease. This is only the second such case described and highlights a possible genotype–phenotype correlation that broadens the recognised clinical spectrum of this rare but treatable disorder.Holocarboxylase Synthetase Deficiency: A Second Case Report With Neonatal Cholestatic Liver DiseaseSophie Manoy, et alhttps://doi.org/10.1002/jmd2.70051