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Disease Profile

Aminoacylase 1 deficiency

Prevalence estimates on Rare Medical Network websites are calculated based on data available from numerous sources, including US and European government statistics, the NIH, Orphanet, and published epidemiologic studies. Rare disease population data is recognized to be highly variable, and based on a wide variety of source data and methodologies, so the prevalence data on this site should be assumed to be estimated and cannot be considered to be absolutely correct.

<1 / 1 000 000

US Estimated

Europe Estimated

Age of onset






Autosomal dominant A pathogenic variant in only one gene copy in each cell is sufficient to cause an autosomal dominant disease.


Autosomal recessive Pathogenic variants in both copies of each gene of the chromosome are needed to cause an autosomal recessive disease and observe the mutant phenotype.


dominant X-linked dominant inheritance, sometimes referred to as X-linked dominance, is a mode of genetic inheritance by which a dominant gene is carried on the X chromosome.


recessive Pathogenic variants in both copies of a gene on the X chromosome cause an X-linked recessive disorder.


Mitochondrial or multigenic Mitochondrial genetic disorders can be caused by changes (mutations) in either the mitochondrial DNA or nuclear DNA that lead to dysfunction of the mitochondria and inadequate production of energy.


Multigenic or multifactor Inheritance involving many factors, of which at least one is genetic but none is of overwhelming importance, as in the causation of a disease by multiple genetic and environmental factors.


Not applicable


Other names (AKA)

Deficiency of the aminoacylase-1 enzyme; ACY1 deficiency; ACY1D


Congenital and Genetic Diseases; Metabolic disorders; Nervous System Diseases


The following summary is from Orphanet, a European reference portal for information on rare diseases and orphan drugs.

Orpha Number: 137754

An inborn error of metabolism marked by a characteristic pattern of urinary N-acetyl amino acid excretion and neurologic symptoms.

Prevalence is unknown but less than 20 cases have been reported in the literature so far.

Clinical description
Most individuals with ACY1D identified so far are children who underwent selective screening tests for inborn errors of metabolism prompted mainly by delayed psychomotor development or by the occurrence of seizures. However, there is a considerable phenotypic variability between ACY1D individuals.

ACY1D is caused by biallelic mutations in the ACY1 gene (3p21.2). ACY1 catalyzes the formation of free amino acids from N-acetylated precursors. The enzyme is strongly expressed in the human brain and is a potential modifier affecting the severity or manifestation of different neurologic diseases.

Diagnostic methods
Diagnosis is made by gas chromatography-mass spectrometry (GC-MS) analysis of urinary organic acids revealing increased levels of N-acetylated amino acids, including methionine, glutamine, alanine, leucine, glycine, valine, and isoleucine derivatives, or by NMR spectroscopy of urine. The diagnosis can be confirmed by identification of mutations in the ACY1 gene and by detection of reduced ACY1 enzyme activity in Epstein-Barr virus (EBV)-transformed lymphoblasts or in fibroblasts.

Genetic counseling
ACY1D is transmitted as an autosomal recessive trait.

Management and treatment
Management is symptomatic only.

Due to the small number of individuals known to have ACY1D and due to the young age of the reported patients, the clinical course cannot be fully predicted and the prognosis is unknown. Characterization of additional patients and long-term follow-up are indicated.

Visit the Orphanet disease page for more resources.


This table lists symptoms that people with this disease may have. For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed. This information comes from a database called the Human Phenotype Ontology (HPO) . The HPO collects information on symptoms that have been described in medical resources. The HPO is updated regularly. Use the HPO ID to access more in-depth information about a symptom.

Medical Terms Other Names
Learn More:
30%-79% of people have these symptoms
Generalized muscle weakness
Muscular hypotonia
Low or weak muscle tone
5%-29% of people have these symptoms
Aplasia/Hypoplasia of the cerebellar vermis
Aplasia/Hypoplasia of the corpus callosum
Global developmental delay
Fluid-filled cyst in spinal cord
Throwing up
1%-4% of people have these symptoms
Wide-set eyes
Widely spaced eyes

[ more ]

Sensorineural hearing impairment
Wide nose
Broad nose
Increased breadth of nose
Increased nasal breadth
Increased nasal width
Increased width of nose

[ more ]

Percent of people who have these symptoms is not available through HPO
Acute encephalopathy
Autosomal recessive inheritance
Cerebellar atrophy
Degeneration of cerebellum
Cerebral atrophy
Degeneration of cerebrum
Delayed CNS myelination
Generalized hypotonia
Decreased muscle tone
Low muscle tone

[ more ]

More active than typical
Muscle weakness
Muscular weakness
Psychomotor retardation
Wide nasal bridge
Broad nasal bridge
Broad nasal root
Broadened nasal bridge
Increased breadth of bridge of nose
Increased breadth of nasal bridge
Increased width of bridge of nose
Increased width of nasal bridge
Nasal bridge broad
Wide bridge of nose
Widened nasal bridge

[ more ]



Making a diagnosis for a genetic or rare disease can often be challenging. Healthcare professionals typically look at a person’s medical history, symptoms, physical exam, and laboratory test results in order to make a diagnosis. The following resources provide information relating to diagnosis and testing for this condition. If you have questions about getting a diagnosis, you should contact a healthcare professional.

Testing Resources

  • The Genetic Testing Registry (GTR) provides information about the genetic tests for this condition. The intended audience for the GTR is health care providers and researchers. Patients and consumers with specific questions about a genetic test should contact a health care provider or a genetics professional.

Learn more

These resources provide more information about this condition or associated symptoms. The in-depth resources contain medical and scientific language that may be hard to understand. You may want to review these resources with a medical professional.

Where to Start

  • Genetics Home Reference (GHR) contains information on Aminoacylase 1 deficiency. This website is maintained by the National Library of Medicine.

In-Depth Information

  • The Monarch Initiative brings together data about this condition from humans and other species to help physicians and biomedical researchers. Monarch’s tools are designed to make it easier to compare the signs and symptoms (phenotypes) of different diseases and discover common features. This initiative is a collaboration between several academic institutions across the world and is funded by the National Institutes of Health. Visit the website to explore the biology of this condition.
  • Online Mendelian Inheritance in Man (OMIM) is a catalog of human genes and genetic disorders. Each entry has a summary of related medical articles. It is meant for health care professionals and researchers. OMIM is maintained by Johns Hopkins University School of Medicine. 
  • Orphanet is a European reference portal for information on rare diseases and orphan drugs. Access to this database is free of charge.
  • PubMed is a searchable database of medical literature and lists journal articles that discuss Aminoacylase 1 deficiency. Click on the link to view a sample search on this topic.