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NGLY1-congenital disorder of deglycosylation

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Description

NGLY1-congenital disorder of deglycosylation (NGLY1-CDDG) is an inherited condition that affects many parts of the body. The severity of the signs and symptoms varies widely among people with the condition.

Individuals with NGLY1-CDDG typically develop features of the condition during infancy. They often have delayed development of speech and motor skills, such as sitting and walking, and weak muscle tone (hypotonia). Many affected individuals have movement abnormalities, such as uncontrolled movements of the limbs (choreoathetosis), and some develop seizures that are difficult to treat. Individuals with NGLY1-CDDG may also have problems with liver function. Some affected individuals have eye abnormalities, including degeneration of the nerves that carry information from the eyes to the brain (optic atrophy) and changes in the light-sensing tissue at the back of the eye (the retina). A reduction or absence of tears (hypolacrima or alacrima) is a common feature of NGLY1-CDDG.

Frequency

NGLY1-CDDG is a rare disorder. At least 46 individuals with the condition have been described in the medical literature.

Causes

NGLY1-CDDG is caused by mutations in the NGLY1 gene. The enzyme produced from this gene, called N-glycanase 1, helps cells get rid of abnormal proteins. It removes chains of sugars (glycans) from misfolded proteins through a process called deglycosylation, which is thought to be an essential step for certain abnormal proteins to be broken down. The gene mutations that cause NGLY1-CDDG impair production of the N-glycanase 1 enzyme, resulting in a severe reduction or absence of the enzyme's function. Without the removal of glycans, the misfolded proteins cannot be broken down. It is thought that the abnormal proteins accumulate and form clumps (aggregates) in cells. These aggregates may damage cells in the brain, liver, and eyes, leading to the signs and symptoms of NGLY1-CDDG.

Inheritance

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.

Other Names for This Condition

  • congenital disorder of deglycosylation
  • deficiency of N-glycanase 1
  • NGLY1-CDDG

Additional Information & Resources

Genetic and Rare Diseases Information Center

Patient Support and Advocacy Resources

Research Studies from ClinicalTrials.gov

Catalog of Genes and Diseases from OMIM

Scientific Articles on PubMed

References

  • Enns GM, Shashi V, Bainbridge M, Gambello MJ, Zahir FR, Bast T, Crimian R, Schoch K, Platt J, Cox R, Bernstein JA, Scavina M, Walter RS, Bibb A, Jones M, Hegde M, Graham BH, Need AC, Oviedo A, Schaaf CP, Boyle S, Butte AJ, Chen R, Chen R, Clark MJ, Haraksingh R; FORGE Canada Consortium, Cowan TM, He P, Langlois S, Zoghbi HY, Snyder M, Gibbs RA, Freeze HH, Goldstein DB. Mutations in NGLY1 cause an inherited disorder of the endoplasmic reticulum-associated degradation pathway. Genet Med. 2014 Oct;16(10):751-8. doi: 10.1038/gim.2014.22. Epub 2014 Mar 20. Erratum in: Genet Med. 2014 Jul;16(7):568. Chen, Rui [added]. Citation on PubMed or Free article on PubMed Central
  • He P, Grotzke JE, Ng BG, Gunel M, Jafar-Nejad H, Cresswell P, Enns GM, Freeze HH. A congenital disorder of deglycosylation: Biochemical characterization of N-glycanase 1 deficiency in patient fibroblasts. Glycobiology. 2015 Aug;25(8):836-44. doi: 10.1093/glycob/cwv024. Epub 2015 Apr 21. Citation on PubMed or Free article on PubMed Central
  • Huang C, Harada Y, Hosomi A, Masahara-Negishi Y, Seino J, Fujihira H, Funakoshi Y, Suzuki T, Dohmae N, Suzuki T. Endo-β-N-acetylglucosaminidase forms N-GlcNAc protein aggregates during ER-associated degradation in Ngly1-defective cells. Proc Natl Acad Sci U S A. 2015 Feb 3;112(5):1398-403. doi: 10.1073/pnas.1414593112. Epub 2015 Jan 20. Citation on PubMed or Free article on PubMed Central
  • Lam C, Ferreira C, Krasnewich D, Toro C, Latham L, Zein WM, Lehky T, Brewer C, Baker EH, Thurm A, Farmer CA, Rosenzweig SD, Lyons JJ, Schreiber JM, Gropman A, Lingala S, Ghany MG, Solomon B, Macnamara E, Davids M, Stratakis CA, Kimonis V, Gahl WA, Wolfe L. Prospective phenotyping of NGLY1-CDDG, the first congenital disorder of deglycosylation. Genet Med. 2017 Feb;19(2):160-168. doi: 10.1038/gim.2016.75. Epub 2016 Jul 7. Citation on PubMed
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