A Turkish newborn infant with cerebellar agenesis/neonatal diabetes mellitus and PTF1A mutation: Classical neonatal diabetes mellitus is defined as hyperglycemia that occurs within the first month of life in term infants. It can be either permanent or transient. Cerebellar agenesis and permanent neonatal diabetes has been previously reported as a new autosomal recessive disorder. Pancreas Transcription Factor 1 Alpha (PTF1A) mutations have been related with this constellation of abnormalities. Here we report a new case of cerebellar agenesis and neonatal diabetes mellitus whose parents are PTF1A mutation carriers.