Inborn errors of metabolism (IEMs) represent a large class of rare genetic disorders. The first IEM was described in 1902 by Sir Archibald Garrod. Since then, many more have been described, variously estimated as >600 or >700. We established a proposed nosology of IEMs, by first defining specific criteria to include a disorder as an IEM, in an attempt to create a self-consistent schema. Our initial approach identified 1015 well-characterized inborn errors of metabolism described in the literature. In addition, there were 111 less well-characterized conditions that may be IEMs but do not meet strict criteria for inclusion in the current nosology, although it is likely that many of these provisional IEMs will eventually be confirmed.

By necessity, the nosology is subject to constant revision as a result of the rapid pace of progress in the field of genetics. Thus, as new disorders are discovered, and our understanding of the pathophysiology of existing disorders continues to improve, frequent updates to the current nosology will be critical to maintain its usefulness. The purpose of this website is to facilitate the continuous digital update of the nosology via the IEMbase.


Ferreira CR, van Karnebeek CDM, Vockley J, Blau N. A proposed nosology of inborn errors of metabolism. Genet Med. 2018 Jun 8. doi: 10.1038/s41436-018-0022-8. [Epub ahead of print] PubMed PMID: 29884839.

1. Disorders of pyrimidine metabolism
2. Disorders of purine metabolism
3. Disorders of nucleotide metabolism
4. Disorders of creatine metabolism
5. Disorders of choline metabolism
6. Disorders of glutathione metabolism
7. Disorders of ammonia detoxification
8. Disorders of amino acid transport
9. Aminoacylase deficiencies
10. Disorders of monoamine metabolism
11. Disorders of phenylalanine and tetrahydrobiopterin metabolism
12. Disorders of tyrosine metabolism
13. Disorders of sulfur amino acid and sulfide metabolism
14. Disorders of branched-chain amino acid metabolism
15. Disorders of lysine metabolism
16. Disorders of proline and ornithine metabolism
17. Disorders of β- and γ-amino acids
18. Disorders of histidine metabolism
19. Disorders of tryptophan metabolism
20. Disorders of glutamate metabolism
21. Disorder of glutamine metabolism
22. Disorder of asparagine metabolism
23. Disorders of serine metabolism
24. Disorders of glycine metabolism
25. Disorders of lipoic acid and iron-sulfur metabolism
26. Disorders of cobalamin metabolism
27. Disorders of folate metabolism
28. Disorders of biotin metabolism
29. Disorders of thiamine metabolism
30. Disorders of riboflavin metabolism
31. Disorders of niacin and NAD metabolism
32. Disorders of pantothenate metabolism
33. Disorders of pyridoxine metabolism
34. Disorder of vitamin C metabolism
35. Disorders of vitamin A metabolism
36. Disorders of vitamin D metabolism
37. Disorder of vitamin E metabolism
38. Disorders of vitamin K metabolism
39. Disorders of molybdenum metabolism
40. Disorders of copper metabolism
41. Disorders of iron metabolism
42. Disorders of zinc metabolism
43. Disorders of manganese metabolism
44. Disorders of selenium metabolism
45. Disorders of magnesium metabolism
46. Disorders of carbohydrate transport and absorption
47. Disorders of galactose metabolism
48. Disorders of fructose metabolism
49. Disorders of the pentose phosphate pathway and polyol metabolism
50. Disorders of insulin secretion and signaling
51. Glycogen storage diseases
52. Disorders of gluconeogenesis
Cytosolic phosphoenolpyruvate carboxykinase deficiency
53. Disorders of glycolysis
54. Disorders of pyruvate metabolism
55. Disorders of the Krebs cycle
56. Disorders of metabolite repair
57. Disorders of mitochondrial carriers
58. Disorders of complex I subunits
59. Disorders of complex I assembly
60. Disorders of complex II subunits
61. Disorders of complex II assembly
62. Disorders of complex III subunits
63. Disorders of complex III assembly
64. Disorders of complex IV subunits
65. Disorders of complex IV assembly and ancillary proteins
66. Disorders of complex V subunits
67. Disorders of complex V assembly
68. Disorders of mitochondrial cytochrome synthesis and incorporation
69. Disorders of mitochondrial DNA depletion, multiple deletion, or intergenomic communication
70. Disorders of mitochondrial transcription and RNA transcript processing
71. Mitochondrial ribosomopathies
72. Disorders of mitochondrial translation factors
73. Disorders of mitochondrial tRNA
74. Disorders of mitochondrial tRNA incorporation and recycling
75. Disorders of mitochondrial fission
76. Disorders of mitochondrial fusion
77. Disorders of mitochondrial phospholipid metabolism
78. Disorders of mitochondrial protein import
79. Disorders of mitochondrial protein quality control
80. Other disorders of mitochondrial homeostasis
81. Primary CoQ10 deficiencies
82. Disorders of carnitine metabolism
83. Disorders of fatty acid oxidation and transport
84. Disorders of ketone body metabolism
85. Disorders of fatty acid synthesis and elongation
86. Disorder of fatty aldehyde metabolism
87. Disorders of glycerol metabolism
88. Disorders of cytoplasmic triglyceride metabolism
89. Disorders of non-mitochondrial phospholipid metabolism
90. Disorders of non-lysosomal sphingolipid metabolism
91. Disorders of eicosanoid metabolism
92. Disorders of palmitoylation
93. Disorders of phosphoinositide metabolism
94. Disorders of lipoprotein metabolism
95. Disorders of cholesterol biosynthesis
96. Disorders of steroid metabolism
97. Disorders of bile acid synthesis
98. Disorders of heme metabolism
99. Disorders of bilirubin metabolism and biliary transport
100. Disorders of autophagy
101. Neuronal ceroid lipofuscinosis
102. Sphingolipidoses
103. Oligosaccharidoses
104. Mucolipidoses
105. Mucopolysaccharidoses
106. Disorders of lysosomal cholesterol metabolism
107. Disorders of lysosomal transport or sorting
108. Disorders of lysosomal protein degradation
109. Disorders of plasmalogen synthesis
110. Disorders of peroxisomal β-oxidation
111. Disorder of peroxisomal α-oxidation
112. Disorders of peroxisomal biogenesis
113. Peroxisomal disorders not involving lipid metabolism
114. Disorders of oxalate metabolism
115. Disorders of N-linked glycosylation
116. Disorders of O-mannosylation
117. Disorders of O-xylosylation and glycosaminoglycan synthesis
118. Disorders of O-GalNAcylation
119. Disorders of O-GlcNAcylation
120. Disorder of O-glucosylation
121. Disorders of O-fucosylation
122. Disorders of glycosylphosphatidylinositol biosynthesis
123. Disorders of glycolipid glycosylation
124. Disorders of dolichol metabolism
125. Disorders of monosaccharide synthesis and interconversion
126. Disorders of nucleotide-sugar synthesis
127. Disorders of Golgi transport
128. Glycosylation disorders of vesicular trafficking
129. Disorders of Golgi homeostasis
130. Disorder of deglycosylation

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