Acidurias, diagnosis

Chalmers, R.A. (1980), Organic acidurias diagnosis and investigation using GC-MS. In Current Developments in the Clinical Applications ofHPLCy GC and MS (eds. A.M. Lawson, C.K. Lim and W. Richmond), Academic Press, London, pp. 233-246. 

The fibroblasts do not convert cyanocobalamin or hydroxocobalamin to methylcobalamin or adenosyl-cobalamin, resulting in diminished activity of both N5-methyltetrahydrofolate homocysteine methyltransferase and methylmalonyl-CoA mutase. Supplementation with hydroxocobalamin rectifies the aberrant biochemistry. The precise nature of the underlying defect remains obscure. Diagnosis should be suspected in a child with homocystinuria, methylmalonic aciduria, megaloblastic anemia, hypomethioninemia and normal blood levels of folate and vitamin B12. A definitive diagnosis requires demonstration of these abnormalities in fibroblasts. Prenatal diagnosis is possible. 

Diagnosis of CPS or OTC deficiency may not be apparent from the blood aminogram. Ornithine levels typically are normal. The presence of hyperammonemia, hyperglu-taminemia, hyperalaninemia and orotic aciduria in a critically ill infant affords presumptive evidence for OTC deficiency. The presence of this blood aminogram without orotic aciduria suggests carbamyl phosphate synthetase deficiency. 

Galactose 1-phosphate uridyl transferase Galactosemia, vomiting, hepatomegaly, jaundice, cataracts, amino aciduria, failure to thrive long-term complications exist even with early diagnosis and treatment... 

Chalmers RA, Lawson AM (1982) Organic Acids in Man Analytical Chemistry, Biochemistry and Diagnosis of the Organic Acidurias. Chapman and Hall, London... 

Acylcarnitine analysis was first performed in urine specimens in the evaluation of patients with organic acidemias. However, because it was found that acylcarnitine analysis of plasma is more informative for the diagnosis of FAO disorders than analysis of urine specimens, plasma has become the preferred specimen [17]. It is only recently that it was shown that urine acylcarnitine analysis still has a role in the diagnostic evaluation of patients with organic acidurias but uninformative or borderline abnormal results of plasma acylcarnitine and urine organic acid analysis [18-21]. In our laboratory, sample preparation and analysis is identical to that of plasma once a urine aliquot has been prepared that is based on the creatinine concentration. 

Hoffmann GF, Sweetman L, et al. (1991) Facts and artefacts in mevalonic aciduria development of a stable isotope dilution GCMS assay for mevalonic acid and its application to physiological fluids, tissue samples, prenatal diagnosis and carrier detection. Clin Chim Acta 198 209-227... 

Hoffmann GF, Brendel SU, et al. (1992) Mevalonate kinase assay using DEAE-cellulose column chromatography for first-trimester prenatal diagnosis and complementation analysis in mevalonic aciduria. J Inherit Metab Dis 15 738-746... 

Quantitative assay of l-2-HGA is important for the diagnosis of L-2-hydroxyglutaric aciduria. Three EPMEs based on maltodextrins with different DE (DE 4.0-7.0 (I), 13.0-17.0 (II) and 16.5-19.5 (III)) were designed for the enantioanalysis of l-2-HGA [40]. The EPMEs can be used reliably for enantiopurity assay of l-2-HGA using the direct potentiometric method in the ranges of 10 9-10 5,10 6-10-3 and 10 8-10-5 mol/L for the EPMEs based on maltodextrins I, II and III, respectively, with very low detection limits. A high reliability was obtained when the electrodes were used for the assay of l-2-HGA in urine samples. 

Whlean et al. (W7) described a follow-up, extending over several years, of two infants with methylmalonic aciduria unresponsive to treatment with vitamin B12. The first patient, a boy, was the child of two first cousins delivery followed an uneventful pregnancy. The child had convulsions 4 days after birth and was found to have a profound metabolic acidosis, and was excreting a large amount of methylmalonic acid in his urine. His serum vitamin B12 concentration was normal. Further studies confirmed a diagnosis of methylmalonic aciduria. 

A second, cytosolic CPS activity (CPSII) occurs in mammals as part of the CAD trifunctional protein that catalyzes the first three steps of pyrimidine synthesis (CPSII, asparate tran-scarbamoylase, and dihydroorotase). The activities of these three enzymes—CPSII, aspartate transcarbamoylase, and dihydroorotase—result in the production of orotic acid from ammonium, bicarbonate, and ATP. CPSII has no role in ureagenesis, but orotic aciduria results from hepatocellular accumulation of carbamyl phosphate and helps distinguish CPSI deficiency from other UCDs. Defects in CPSI classically present with neonatal acute hyperammonemic encephalopathy. The plasma citrulline and urine orotic acid concentrations are both low. A definitive diagnosis can be established by enzyme assay of biopsied liver tissue or by mutation analysis. 

In the first instance, it is used to confirm a diagnosis when dealing with a patient with a metabolic problem. When the routine chemical screens indicate the presence of abnormal metabolites or raised levels of the usual metabolites, then MS can positively confirm their identity and thus a diagnosis, or, should it be a new inborn error, point to the metabolic pathways which are affected. In many of the organic acidurias described, the defect leads to gross excretion of one or more compounds and, as quantitative extraction is not necessary for their detection, simple solvent or other methods are normally used. In some instances it is vital that analysis be carried out quickly so as to indicate the most suitable clinical management of an acutely ill patient. 

Chalmers RA, Lawson AM. Organic acids in man— analytical chemistry, biochemistry, and diagnosis of the organic acidurias. London Chapman and Hall, 1982. 

Inborn errors of metabolism, such as the 2-hydroxyglutaric aciduria and maple syrup urine disease, can be detected by a similar characterisation of the metabolic pattern of the urine. Whereas 250-MHz field strength turned out to be too small to find the differences in the hydroxyl acid pattern in the urine [43], 750 and 800-MHz enable one to make a differential diagnosis of the inborn diseases [44]. 

The most Important use of body odors in disease diagnosis relates to the infant diseases involving errors in amino acid metabolism. Strong and unusual odors are manifest in the breath, sweat, and urine of these individuals. Table II summarizes several known acidurias, the amino acids that are not properly metabolized, and the odors associated with the compounds which accumulate and can be detected in the urine ( ). In the case of the Maple Syrup Urine and Oasthouse syndrome, the keto- and hydroxy- acids which have been identified may not be responsible for the observed maple and celery/yeast odors (.9). Alternatively, these odors could be the result of conversion of 2-keto-butyrlc acid to methyl-ethyl-tetronlc acid (Slusser s lactone) which is used as an extender in maple and celery flavors and has a maple syrup-like odor (R. Soukup, personal communication). With these acidurias it is imperative that an immediate diagnosis is made, since corrective diet can prevent the brain damage that results from these diseases. This is readily done on an olfactory basis which can subsequently be supported by gas chromatographic... 

Olpin, S.E., Manning, N.J., Carpenter, K.., Middleton, B. Pollitt, R.J. (1992) J. InheritedMetab. Dis. 15, 883-890. Differential diagnosis of hydroxydiearboxylic aciduria based on release of H20from [9,10- H]myristic and [9,10- H]palmitic acids by intact cultured fibroblasts. 

KOlker S, et al. Diagnosis and management of glutaric aciduria type I-revised recommendations. 1 Inherit Metab Dis. 2011 34(3) 677-94. 

Gas Chromatographic Method of Analysis for Urinary Organic Acids. II. Description of the Procedures, and Its Application to Diagnosis of Patients with Organic Acidurias Clin. Chem. (Winston-Salem, N. C.) 26(13) 1847-1853 (1980) CA 94 79520s... 

TLC has been used to identify amino acids from plant and animal tissues and fluids. Heathcote (1979) described the use of various two-dimensional solvent systems with and without pretreatment of samples (for cleanup purposes) for the analysis of free-pool amino acids in bacteria and molds. Berry (1973) used various unidimensional solvent systems for TLC diagnosis of amino acidurias in human plasma. Hanes et al. (1961) used unidimensional solvent systems for the analysis of the 20 protein amino acids from plants. Harborne (1984) has discussed... 

Fig. 6.1. The L-leucine degradative pathway. Reactions for which inherited metabolic disorders have not been conclusively identified include A, leucine-isoleucine aminotransferase and the majority of the 3-methylglutaconic acidurias (6.6-6.7). 6.1, Branched-chain a-ketoacid dehydrogenase (BCKD) complex, a reaction also occurring in the initial steps of L-isoleucine and L-valine degradation 6.2, isovaleryl-CoA dehydrogenase 6.3, 3-methylcrotonyl-CoA carboxylase 6.4, 3-methylglutaconyl-CoA hydra-tase 6.8, HMG-CoA lyase. Pathologic urinary metabolites used as specific markers in the differential diagnosis are presented in squares. Abbreviation Co A, coenzyme A...

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