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UPB1 gene

beta-ureidopropionase 1

Normal Function

The UPB1 gene provides instructions for making an enzyme called beta-ureidopropionase. This enzyme is involved in the breakdown of molecules called pyrimidines, which are building blocks of DNA and its chemical cousin RNA.

The beta-ureidopropionase enzyme is involved in the last step of the process that breaks down pyrimidines. This step converts N-carbamyl-beta-aminoisobutyric acid to beta-aminoisobutyric acid and also breaks down N-carbamyl-beta-alanine to beta-alanine, ammonia, and carbon dioxide. Both beta-aminoisobutyric acid and beta-alanine are thought to play roles in the nervous system. Beta-aminoisobutyric acid increases the production of a protein called leptin, which has been found to help protect brain cells from damage caused by toxins, inflammation, and other factors. Research suggests that beta-alanine is involved in sending signals between nerve cells (synaptic transmission) and in controlling the level of a chemical messenger (neurotransmitter) called dopamine.

Health Conditions Related to Genetic Changes

Beta-ureidopropionase deficiency

At least 16 UPB1 gene mutations have been identified in people with beta-ureidopropionase deficiency. This disorder causes excessive amounts of N-carbamyl-beta-aminoisobutyric acid and N-carbamyl-beta-alanine to be released in the urine. Affected individuals may also have a variety of neurological problems such as seizures and intellectual disability, ranging from mild to severe. Some people with beta-ureidopropionase deficiency have no neurological symptoms, and the disorder can only be diagnosed with laboratory testing.

The mutations that cause beta-ureidopropionase deficiency reduce or eliminate beta-ureidopropionase enzyme activity. Loss of this enzyme function reduces the production of beta-aminoisobutyric acid and beta-alanine, and leads to an excess of their precursor molecules, N-carbamyl-beta-aminoisobutyric acid and N-carbamyl-beta-alanine, which are released in the urine. Reduced production of beta-aminoisobutyric acid and beta-alanine may impair their functions in the nervous system, leading to neurological problems in some people with beta-ureidopropionase deficiency. The extent of the reduction in enzyme activity caused by a particular UPB1 gene mutation, along with other genetic and environmental factors, may determine whether people with beta-ureidopropionase deficiency develop neurological problems and the severity of these problems.

More About This Health Condition

Other Names for This Gene

  • beta-alanine synthase
  • beta-ureidopropionase
  • BUP1
  • n-carbamoyl-beta-alanine amidohydrolase
  • ureidopropionase, beta

Additional Information & Resources

Tests Listed in the Genetic Testing Registry

Scientific Articles on PubMed

Catalog of Genes and Diseases from OMIM

Gene and Variant Databases


  • Nakajima Y, Meijer J, Dobritzsch D, Ito T, Meinsma R, Abeling NG, Roelofsen J, Zoetekouw L, Watanabe Y, Tashiro K, Lee T, Takeshima Y, Mitsubuchi H, Yoneyama A, Ohta K, Eto K, Saito K, Kuhara T, van Kuilenburg AB. Clinical, biochemical and molecular analysis of 13 Japanese patients with beta-ureidopropionase deficiency demonstrates high prevalence of the c.977G > A (p.R326Q) mutation [corrected]. J Inherit Metab Dis. 2014 Sep;37(5):801-12. doi: 10.1007/s10545-014-9682-y. Epub 2014 Feb 14. Erratum In: J Inherit Metab Dis. 2014 Nov;37(6):1023. Citation on PubMed or Free article on PubMed Central
  • van Kuilenburg AB, Dobritzsch D, Meijer J, Krumpel M, Selim LA, Rashed MS, Assmann B, Meinsma R, Lohkamp B, Ito T, Abeling NG, Saito K, Eto K, Smitka M, Engvall M, Zhang C, Xu W, Zoetekouw L, Hennekam RC. ss-ureidopropionase deficiency: phenotype, genotype and protein structural consequences in 16 patients. Biochim Biophys Acta. 2012 Jul;1822(7):1096-108. doi: 10.1016/j.bbadis.2012.04.001. Epub 2012 Apr 14. Citation on PubMed
  • van Kuilenburg AB, Meinsma R, Assman B, Hoffman GF, Voit T, Ribes A, Lorente I, Busch R, Mayatepek E, Abeling NG, Wevers RA, Rutsch F, van Gennip AH. Genetic analysis of the first 4 patients with beta-ureidopropionase deficiency. Nucleosides Nucleotides Nucleic Acids. 2006;25(9-11):1093-8. doi: 10.1080/15257770600956870. Citation on PubMed
  • van Kuilenburg AB, Meinsma R, Beke E, Assmann B, Ribes A, Lorente I, Busch R, Mayatepek E, Abeling NG, van Cruchten A, Stroomer AE, van Lenthe H, Zoetekouw L, Kulik W, Hoffmann GF, Voit T, Wevers RA, Rutsch F, van Gennip AH. beta-Ureidopropionase deficiency: an inborn error of pyrimidine degradation associated with neurological abnormalities. Hum Mol Genet. 2004 Nov 15;13(22):2793-801. doi: 10.1093/hmg/ddh303. Epub 2004 Sep 22. Citation on PubMed

The information on this site should not be used as a substitute for professional medical care or advice. Contact a health care provider if you have questions about your health.