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Table 3 biochemical parameters that correlate with plasma ammonia for PA and MMA

From: Understanding acute metabolic decompensation in propionic and methylmalonic acidemias: a deep metabolic phenotyping approach

Analyte Matrix N R2 P-value Known
Targeted metabolic assays
 Ketones Plasma 5 1.00 < 0.0001 No
 2-Methylcitric acida Plasma 42 0.77 < 0.0001 Yes
 Arachidonic acid Plasma 44 0.72 < 0.0001 No
 3-Hydroxyisovaleric acid Plasma 39 0.70 0.0058 No
 2-Methylcitric acida Plasma 79 0.67 < 0.0001 Yes
 3-Hydroxyisovaleric acid Urine 163 0.67 < 0.0001 No
 3-Hydroxypropionic acid Plasma 46 0.66 < 0.0001 Yes
 Glutaric acid Urine 149 0.64 < 0.0001 No
 Pipecolinic acid Plasma 68 0.52 0.0432 No
 Alanine/lysine ratio Plasma 94 −0.68 < 0.0001 No
 C4-DC carnitine Plasma 225 −0.55 < 0.0001 No
 C14:1 carnitine/C2 carnitine ratio Plasma 88 −0.53 0.0011 No
 Alanine/(phenylalanine+tyrosine) ratio Plasma 94 −0.51 0.0013 No
Untargeted DI-HRMS
 2-Methylcitric acid (3 isomers) Plasma 157 0.68 < 0.0001 Yes
 Alanyl-Isoleucine (3 isomers) Plasma 157 0.65 < 0.0001 No
 3-Hydroxyisovaleric acid (10 isomers) Plasma 157 0.64 < 0.0001 No
 3-Methyl-2-oxovaleric acid (7 isomers) DBS 122 0.56 < 0.0001 No
 Isobutyrylglycine (6 isomers) Plasma 157 0.55 < 0.0001 No
 Indole-5,6-quinone DBS 122 0.53 < 0.0001 No
 Propionylglycine (9 isomers) DBS 122 0.52 < 0.0001 Yes
 3-Hydroxyphenylacetic acid (3 isomers) Plasma 157 0.51 < 0.0001 No
 Indole-5,6-quinone Plasma 157 0.51 < 0.0001 No
 Pyrocatechol sulfate DBS 122 −0.65 < 0.0001 No
 Threonic acid DBS 122 −0.60 < 0.0001 No
 Trimethylamine N-oxide DBS 122 −0.59 < 0.0001 No
 Stearoylcarnitine DBS 122 −0.58 < 0.0001 No
 Methylmalonic acid (3 isomers) DBS 122 −0.57 < 0.0001 No
 Ergothioneine DBS 122 −0.55 < 0.0001 No
  1. All p-values were adjusted according to the Bonferroni method. A p-value < 0.05 was considered statistically significant. An R2 value of > 0.50 or < − 0.50 was considered biologically relevant. aDue to methodological developments over time, two different diagnostic assays for 2-methylcitric acid were included in the analysis, both demonstrating a solid positive correlation with plasma ammonia. Abbreviations DI-HRMS direct-infusion high-resolution mass spectrometry, N number of samples