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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

AnalyteMatrixNR2P-valueKnown
Targeted metabolic assays
 KetonesPlasma51.00< 0.0001No
 2-Methylcitric acidaPlasma420.77< 0.0001Yes
 Arachidonic acidPlasma440.72< 0.0001No
 3-Hydroxyisovaleric acidPlasma390.700.0058No
 2-Methylcitric acidaPlasma790.67< 0.0001Yes
 3-Hydroxyisovaleric acidUrine1630.67< 0.0001No
 3-Hydroxypropionic acidPlasma460.66< 0.0001Yes
 Glutaric acidUrine1490.64< 0.0001No
 Pipecolinic acidPlasma680.520.0432No
 Alanine/lysine ratioPlasma94−0.68< 0.0001No
 C4-DC carnitinePlasma225−0.55< 0.0001No
 C14:1 carnitine/C2 carnitine ratioPlasma88−0.530.0011No
 Alanine/(phenylalanine+tyrosine) ratioPlasma94−0.510.0013No
Untargeted DI-HRMS
 2-Methylcitric acid (3 isomers)Plasma1570.68< 0.0001Yes
 Alanyl-Isoleucine (3 isomers)Plasma1570.65< 0.0001No
 3-Hydroxyisovaleric acid (10 isomers)Plasma1570.64< 0.0001No
 3-Methyl-2-oxovaleric acid (7 isomers)DBS1220.56< 0.0001No
 Isobutyrylglycine (6 isomers)Plasma1570.55< 0.0001No
 Indole-5,6-quinoneDBS1220.53< 0.0001No
 Propionylglycine (9 isomers)DBS1220.52< 0.0001Yes
 3-Hydroxyphenylacetic acid (3 isomers)Plasma1570.51< 0.0001No
 Indole-5,6-quinonePlasma1570.51< 0.0001No
 Pyrocatechol sulfateDBS122−0.65< 0.0001No
 Threonic acidDBS122−0.60< 0.0001No
 Trimethylamine N-oxideDBS122−0.59< 0.0001No
 StearoylcarnitineDBS122−0.58< 0.0001No
 Methylmalonic acid (3 isomers)DBS122−0.57< 0.0001No
 ErgothioneineDBS122−0.55< 0.0001No
  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