Aminoacylase I deficiency: a novel inborn error of metabolism.

This is the first report of a patient with aminoacylase I deficiency. High amounts of N-acetylated amino acids were detected by gas chromatography-mass spectrometry in the urine, including the derivatives of serine, glutamic acid, alanine, methionine, glycine, and smaller amounts of threonine, leucine, valine, and isoleucine. NMR spectroscopy confirmed these findings and, in addition, showed the presence of N-acetylglutamine and N-acetylasparagine. In EBV transformed lymphoblasts, aminoacylase I activity was deficient. Loss of activity was due to decreased amounts of aminoacylase I protein. The amount of mRNA for the aminoacylase I was decreased. DNA sequencing of the encoding ACY1 gene showed a homozygous c.1057 C>T transition, predicting a p.Arg353Cys substitution. Both parents were heterozygous for the mutation. The mutation was also detected in 5/161 controls. To exclude the possibility of a genetic polymorphism, protein expression studies were performed showing that the mutant protein had lost catalytic activity.

MRI findings in a neonate with cerebellar agenesis.

Cerebellar agenesis is a rarely observed malformation that is frequently associated with other defects. We describe a neonate with an isolated cerebellar agenesis. In addition to the absence of recognizable cerebellar tissue, cranial magnetic resonance imaging demonstrated a hypoplastic base of the pons and absence of the normal outline of the inferior olives. Other major cerebral malformations were not found. As a developmental defect, cerebellar agenesis is heterogeneous because it occurs either as an anatomically isolated anomaly or as part of a more complex cerebral malformation. The pathogenesis and molecular basis of isolated cerebellar agenesis is unknown.