Aminoacylase 1 deficiency

Synonyms

5

Overview

A rare genetic disorder caused by an enzyme (aminoacylase-1) deficiency. It can cause neurological problems; the pattern and severity of signs and symptoms vary widely among affected individuals. Individuals with this condition typically have delayed development of mental and motor skills (psychomotor delay). They can have movement problems, reduced muscle tone (hypotonia), mild intellectual disability, and seizures. However, some people with aminoacylase 1 deficiency have no health problems related to the condition. A key feature common to all people with aminoacylase 1 deficiency is high levels of modified protein building blocks (amino acids), called N-acetylated amino acids, in the urine.

Symptoms

• Syringomyelia
• Seizures
• Reduced muscle tone
• Psychomotor delay

Causes

Aminoacylase 1 deficiency is caused by mutations in the ACY1 gene. This gene provides instructions for making an enzyme called aminoacylase 1, which is involved in the breakdown of proteins when they are no longer needed.

Mutations in the ACY1 gene lead to an aminoacylase 1 enzyme with little or no function. Without this enzyme's function, acetyl groups are not efficiently removed from a subset of amino acids during the breakdown of proteins.

This condition is inherited in an autosomal recessive pattern, which means both copies of the gene in each cell have mutations. The parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but they typically do not show signs and symptoms of the condition.

Diagnosis

There is a specific pattern of N-acetyl amino acid excretion in the urine. The diagnosis can be confirmed by sequencing of the aminoacylase 1 gene.

Resources

• NIH