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PubMed1999

Clinical and biochemical approach to the neonate with a suspected inborn error of amino acid and organic acid metabolism.

Disorders of amino acid and organic acid metabolism collectively represent a group of over 70 inherited diseases that are most frequently encountered in the neonatal period. A neonate with clinical symptoms caused by one of these disorders is a real clinical emergency, a situation complicated by the similarities to the manifestations seen in sepsis or asphyxia. Delay of diagnosis and proper treatment often results in severe morbidity and high mortality. The vast majority of these patients are likely to be transferred to a neonatal intensive care unit, suggesting that amino acid and organic acid biochemical screenings should be performed in these newborns routinely at admission. The analysis of amino acids and acylcarnitines in blood spots by tandem mass spectrometry has the potential to significantly improve the morbidity and mortality rates of metabolic disorders with neonatal presentation. In the case of disorders lacking an effective treatment, an early diagnosis could lead to proper genetic counseling of the parents and to the option of reliable prenatal diagnosis of future pregnancies. This review offers an updated summary of the clinical, biochemical, and therapeutic features of the aminoacidopathies and organic acidurias most likely to be encountered in neonatal clinical practice.

Amino Acid Metabolism, Inborn Errors↗
PubMed1992

[Clinical heterogeneity of the autistic syndrome: a study of 60 families].

Sixty families ascertained through a single proband, has helped to better define infantile autism as a heterogeneous group of disorders. Forty four patients showed a characteristic facio- auricular dysplasia. Twenty four of these, showed increased pyruvate and lactate and laboratory findings of metabolic acidosis i.e., anion gap above 18 mEq/L or serum bicarbonate below 21 mEq/L but only nine of these probands demonstrated reduction of plasma bicarbonate below 18 mEq/lt. Plasma amino acids in 17 probands and matched controls showed increased taurine with the rest of amino acids significantly (p less than 0.05) below the control level. Glutamate and aspartate were also significantly elevated (p less than 0.05; Student t-test). Segregation analysis in thirty four of these families which linked through at least one ancestral family name, suggested autosomal recessive inheritance (p = 0.20). Three out of eight probands who received megadoses of pyridoxine (Vitamin B6), subjectively gained in language abilities, affectivity and response to behavior modification therapy. Five autistic patients proved to have clinically defined syndromes: two with the Martin-Bell syndrome, and three girls affected respectively with the Rett syndrome, phenylketonuria and dicarboxylic aciduria.

Acidosis↗
PubMed2001

[Mitochondrial DNA T to G mutation 8993 in Leigh encephalopathy and organic aciduria].

We report a 10-month-old female infant with Leigh encephalopathy caused by a T to G mutation at nucleotide 8993 of mitochondrial DNA. Initial manifestations were diarrhea and pyrexia, followed by disturbance of consciousness. Blood chemistry showed lactic acidosis, and cranial T2 weighted magnetic resonance imaging demonstrated symmetric high-intensity areas in the basal ganglia, consistent with Leigh encephalopathy. Analysis of urinary organic acids revealed a increase of alpha-ketoglutamate. Derivatives of branched chain amino acids, which accumulate in maple syrup disease, were also increased. Lipoamide dehydrogenase (E3) deficiency was initially suspected; however, normal activity of pyruvate dehydrogenase complex excluded the diagnosis. The organic aciduria disappeared after two weeks. The CNS lesions in our case were observed more prominently in the floor of the bilateral frontal lobes than in the globus pallidus and putamen. In this case, mitochondrial DNA mutation may have caused organic aciduria and the atypical imaging findings.

DNA, Mitochondrial↗
PubMed1987

Amniotic fluid propionylcarnitine in methylmalonic aciduria.

Amniotic fluid samples from pregnancies complicated by foetal methylmalonic aciduria and from metabolically normal pregnancies were obtained at 16-18 weeks of gestation and analysed for total, free and acylcarnitine and individual carnitine esters. The amniotic fluid concentrations of total acylcarnitine and propionylcarnitine were higher in pregnancies with higher in pregnancies with methylmalonic aciduria than in normal pregnancies. The predominant carnitine ester was propionylcarnitine in the methylmalonic aciduria group and acetylcarnitine in the normal group. These findings suggest that in methylmalonic aciduria, abnormalities of carnitine metabolism already occur early in gestation. The amount of propionylcarnitine in amniotic fluid may be useful as an additional indicator of foetal methylmalonic aciduria.

Acetylcarnitine↗
PubMed1987

3-Hydroxy-3-methylglutaric aciduria: response to carnitine therapy and fat and leucine restriction.

A female infant, born to first cousin parents, lapsed into coma with severe metabolic acidosis on day three of life. The gas chromatographic/mass spectrometric urinary organic acid profile showed marked elevation of the leucine metabolites 3-hydroxy-3-methylglutaric, 3-methylglutaconic, 3-methylglutaric and 3-hydroxy-isovaleric acids. Less than 5% of the normal activity of the enzyme 3-hydroxy-3-methylglutaryl CoA lyase was detected in cultured skin fibroblasts. The patient's total and free carnitine was initially low but rose to normal levels after placing her on DL-carnitine (100 mg kg-1 d-1). On a diet providing 87 mg kg-1 d-1 of leucine and only 25% of total calories as fat and 2 g kg-1 d-1 protein, the concentration of the urinary organic acids fell markedly. She is now 15 months old with normal growth and development. This regimen appears effective in the early treatment of 3-hydroxy-3-methylglutaric aciduria.

Acidosis↗
PubMedDate not supplied

'Classical' organic acidurias, propionic aciduria, methylmalonic aciduria and isovaleric aciduria: long-term outcome and effects of expanded newborn screening using tandem mass spectrometry.

'Classical organic acidurias' comprise isovaleric aciduria, propionic aciduria and methylmalonic aciduria. Available data from the literature suggest that the use of 'new' therapeutic strategies has improved survival but has not modified neurodevelopment. Progressive neurocognitive deterioration is almost invariably present in propionic and methylmalonic acidurias, while large-scale studies on the long-term outcome of patients with isovaleric aciduria are still lacking. In order to answer to some of the questions suggested by Wilson and Jungner in 1968 about the criteria of disease screening, we compared the natural history of patients with 'classical' organic acidurias diagnosed on clinical bases to those diagnosed through neonatal mass screening using tandem mass spectrometry. Decreased early mortality, less severe symptoms at diagnosis, and more favourable short-term neurodevelopmental outcome were recorded in patients identified through expanded newborn screening. The short duration of follow-up so far does not allow us to draw final conclusions about the effects of newborn screening on long-term outcome. The evaluation of the effect of neonatal screening on the detection rate of these three diseases showed that the incidence of isovaleric aciduria was significantly higher in the screening population than in clinically detected cases, with no changes for propionic and methylmalonic acidurias. Further multicentre longitudinal studies are needed to assess the usefulness of expanded newborn screening for 'classical' organic acidurias and to better understand the clinical spectrum of these diseases. This paper describes the long-term outcome and the impact of expanded newborn screening on the so-called 'classical' organic acidurias (propionic aciduria, methylmalonic aciduria and isovaleric aciduria).

Amino Acid Metabolism, Inborn Errors↗
PubMed1971

Hyperoxaluria in L-glyceric aciduria: possible pathogenic mechanism.

The effect of hydroxypyruvate on synthesis of oxalate and glycolate from glyoxylate was studied in in vitro preparations from normal human erythrocytes and leukocytes, rat liver, and with purified lactate dehydrogenase from beef heart. In the presence of reduced nicotinamide adenine dinucleotide, hydroxypyruvate stimulated the oxidation of glyoxylate to oxalate and decreased the reduction of glyoxylate to glycolate. These findings may explain the hyperoxaluria seen in L-glyceric aciduria (type II primary hyperoxaluria).

Alcohol Oxidoreductases↗
PubMed1984

Hyperammonemia.

A symptomatic elevation in plasma ammonium concentration, termed hyperammonemia, is associated with numerous congenital and acquired conditions (Table 11). In some cases, such as urea cycle disorders, ammonia is the principal toxin. In other instances, such as portal systemic encephalopathy, it is but one of a number of metabolic disturbances, However, in either case hyperammonemic episodes should be treated aggressively to prevent coma, subsequent brain damage, or death. This involves restricting protein intake, providing adequate calories, and giving agents that remove accumulated nitrogen. Long-term therapy relies on diagnosing the specific disease rate. This rarely requires invasive procedures such as liver biopsy. In most cases measurement of plasma amino acids and urinary organic acids will identify the defect. Treatment involving restriction of nitrogen intake, vitamin supplementation, or stimulation of alternative pathways of waste nitrogen excretion can then be instituted. Early therapy, especially in patients with neonatal-onset hyperammonemia, is imperative to avoid severe brain damage. On this basis, the plasma ammonium level should be determined in virtually every newborn with lethargy, hypotonia, poor feeding, seizures, and/or respiratory distress of unclear origin (Table 12).

Acetyltransferases↗
PubMed1991

Prospective treatment of urea cycle disorders.

We present a diagnostic and therapeutic protocol designed to prevent clinical expression of inborn errors of urea synthesis in the neonatal period, and discuss the long-term developmental outcome of survivors. The families of 32 infants, among 43 identified prenatally as being at risk for a urea cycle disorder, chose to have their infants treated according to a diagnostic and therapeutic protocol, beginning at birth. The therapy was effective in avoiding neonatal hyperammonemic coma and death in seven patients with carbamoyl phosphate synthetase deficiency, argininosuccinate synthetase deficiency, and argininosuccinate lyase deficiency. When treated prospectively, five of eight patients with ornithine transcarbamylase deficiency avoided severe hyperammonemia and survived the neonatal period. Two patients with carbamoyl phosphate synthetase deficiency and two with ornithine transcarbamylase deficiency have subsequently died; three additional patients with the latter disorder have received orthotopic liver transplants. Our experience suggests that these surviving patients have had a more favorable neurologic outcome than patients rescued from neonatal hyperammonemic coma. However, all of them require a burdensome medical regimen and may have handicaps that include impairment of development and recurrent episodes of hyperammonemia. Further, those with deficiency of carbamoyl phosphate synthetase or ornithine transcarbamylase have a high mortality rate.

Amino Acid Metabolism, Inborn Errors↗
PubMedDate not supplied

[Screening for congenital metabolic diseases in mentally retarded patients in 6 psychiatric institutions of Lower Saxony].

The results of screening for inborn errors of metabolism in patients in six institutions for the mentally retarded in Lower Saxony are presented. A battery of standard chemical and chromatographic tests for amino acids, carbohydrates and mucopolysaccharides in urine were employed. Combined gas chromatography-mass spectrometry was used to detect organic aciduria. All together 975 patients - 347 females and 628 males - aged from 5 to 93 years were studied. 78.6% of the patients were over 20 years of age. There were positive findings in 56 cases: phenylketonuria (n = 8), alcaptonuria (1), pentosuria (5), galactosuria (2), tryptophanuria (1), xanthurenic aciduria (3), mucopolysaccharidosis type III A (1), hyperglycinemia with hyperglycinuria (1), renal hyperaminoaciduria (9, lactic aciduria (3), 4-hydroxyphenylaceticaciduria (2), organic aciduria (12) and mellituria (8) of unknown type. The organic acids most often detected in urine were lactic, 4-hydroxyphenylacetic and 3-hydroxybutyric acids. Only 20 of the patients (2.0%) excreted appreciable amounts of benzoic acid in urine. The results are discussed and compared with other investigations.

Adolescent↗
PubMed1991

Cerebellar ataxia with glutamic aciduria.

We report a case of cystinuria and glutamic aciduria, presenting with progressive cerebellar manifestations. She had cerebellar type dysarthria and limb ataxia. Head MRI revealed cerebellar atrophy. Urinary amino acid analysis showed excessive excretion of glutamate and the dibasic amino acids (cystine, arginine, lysine, and ornithine). Cystine and glutamic acid are thought to be transported in a common membrane transport system. Reduction of glutamic acid and cystine in the cerebrospinal fluid was revealed. A relationship between cystinuria and cerebellar manifestation was discussed.

Adult↗