The response to L-carnitine and glycine therapy in isovaleric acidaemia

The profound metabolic disturbances which occur in isovaleric acidaemia are due to the intramitochondrial accumulation of isovaleryl coenzyme A (CoA) with a consequent reduction in the availability of free CoA. Secondary carnitine insufficiency is also a feature of this and other disorders of organic acid metabolism. A patient who presented at 2.5 years of age was diagnosed using capillary GC-MS as having isovaleric acidaemia. She showed the full spectrum of abnormal organic acids previously associated with the 'neonatal' form of the disease despite her late presentation, indicating that it is inappropriate to refer to acute early and late onset forms of isovaleric acidaemia. Instead, a spectrum of disease exists, determined by environmental factors, residual enzyme activities and modifying effects of different phenotypes in different individuals. She also showed evidence of carnitine insufficiency. An oral challenge with L-carnitine resulted in the excretion of large amounts of urinary acylcarnitines which were shown by use of fast atom bombardment mass spectrometry to be primarily isovalerylcarnitine. Regular glycine supplementation caused no significant increase in urinary isovalerylglycine and had to be stopped because of side-effects after 5 days. An oral L-carnitine challenge during glycine supplementation resulted in a marked increase in isovalerylglycine excretion, again associated with the excretion of large amounts of isovalerylcarnitine. Carnitine acts by removing (detoxifying) intramitochondrial isovaleryl groups and, in the presence of glycine, it promotes the formation of isovalerylglycine. We believe L-carnitine supplementation is of value in the treatment of isovaleric acidaemia and that, in the present case, L-carnitine together with a moderate dietary restriction has proved to be the optimum form of therapy.

Liver transplantation in a 23-year-old tyrosinaemia patient: effects on the renal tubular dysfunction

Orthotopic liver transplantation was performed on a 23-year-old female with hereditary tyrosinaemia. The disorder was diagnosed at 7 years of age due to severe rickets, and the patient was treated with a diet restricted in phenylalanine and tyrosine. Nineteen months before the transplantation she had an acute episode of diffuse gastrointestinal bleeding due to portal hypertension. Three subsequent bleeding episodes with accompanying ascites and signs of encephalopathy were considered life-threatening. Nine months after the liver transplantation the patient is well, but serum transaminases are slightly elevated. Without dietary restrictions serum tyrosine and inorganic phosphate are normalized, no succinylacetone can be detected in serum, and urinary excretion of p-hydroxyphenyllactate and p-hydroxyphenylpyruvate is normal. Excretion of amino acids, glucose and beta 2-microglobulin decreased significantly after the transplantation but is still elevated. The succinylacetone concentration in urine is about 20% of the preoperative level. After an oral tyrosine load, succinylacetone excretion increased sevenfold but no deterioration of the renal tubular function was observed and no tyrosine metabolites were detectable in serum. The findings indicate that the defective tyrosine metabolism occurs in the kidneys, but does not produce tubular dysfunction. The residual tubular dysfunction of the patient is probably due to irreversible damage of the tubular epithelium.

A new patient with hyperornithinaemia, hyperammonaemia and homocitrullinuria treated early with low protein diet

The characteristic biochemical disturbances of the amino acid and pyrimidine metabolism are described and illustrated by the first case of the HHH syndrome reported in Norway. The disorder was treated with a low protein diet at an early age and the patient developed normally on this diet.

The dietary challenge of propionicacidaemia in an Asian girl

An Asian girl with propionicacidaemia, now aged 2 1/2 years, is presented. The low protein regime required to treat this condition, along with the cultural differences and communication problems involved in dealing with this Moslem family are described.

[Neonatal form of isovaleric acidemia. Apropos of a new case]

The case reported concerns a 18 day-old girl who was hospitalized for severe toxemia. The nauseous smell, and significant ketonuria led us to suspect a disorder in amino-acids metabolism. Diagnosis was proven by gas chromatography. With adequate diet, evolution was favourable and the child had a normal psycho-motor development.

The dietary management of inborn errors of metabolism

Many inborn errors have now been described that can be treated by alterations in diet. Such treatment requires an understanding of both the biochemistry of the defect and of normal nutritional requirements. The principal strategies are cofactor therapy, steps to prevent accumulation of toxic metabolites and the replacement of essential nutrients that are deficient as a result of the metabolic block. It is essential to make sure that any diet used for more than a brief period is complete and capable of sustaining normal growth and development. The treatment of disorders of carbohydrate and amino acid metabolism including organic acidaemias and disorders of the urea cycle and of fat oxidation are discussed.

Nutrition support of inborn errors of amino acid metabolism

Programs for nutrition support of patients with phenylketonuria, maternal phenylketonuria, branched chain ketoaciduria and vitamin B-6 non-responsive homocystinuria were written in BASIC. These programs plan diets to fill diet prescriptions using natural foods, available amino acid-free or restricted elemental products, milk or infant proprietary formulae and protein-free fat and carbohydrate sources. Emphasis is placed on satisfying the amino acid and protein prescriptions simultaneously. The final semisynthetic formula is evaluated for vitamins, minerals, renal solute load and renal net acid excretion. Fluid requirement is estimated. The paper describes how the conventional protocols are enhanced by computerization and details the requisite calculations.

Guanidino compounds in plasma, urine and cerebrospinal fluid of hyperargininemic patients during therapy

The concentrations of guanidino compounds were determined in urine, plasma and cerebrospinal fluid of two patients with hyperargininemia during dietary therapy. alpha-Keto-delta-guanidinovaleric acid, N-alpha-acetylarginine, argininic acid and gamma-guanidinobutyric acid were increased in urine. In plasma, these compounds together with creatine, guanidinoacetic acid, arginine and homoarginine were also increased. In cerebrospinal fluid, only arginine, homoarginine and argininic acid were increased. Trace amounts of alpha-keto-delta-guanidinovaleric acid were found in cerebrospinal fluid of the patient treated with only a low-arginine diet. The concentrations of guanidinosuccinic acid are decreased in urine, plasma and cerebrospinal fluid. During a low-arginine diet, together with sodium benzoate therapy, the plasma and cerebrospinal fluid arginine values returned to normal. There was also a normalization of plasma guanidinoacetic acid and a marked decrease in plasma N-alpha-acetylarginine and argininic acid.

Alanine decreases the protein requirements of infants with inborn errors of amino acid metabolism

Supplementation with alanine was found to increase growth in weight and nitrogen balance in 5 infants with a variety of inborn errors of amino acid metabolism receiving diets restricted in protein. The addition of alanine to the regimen led to a mean increase in weight of 15 g/day. This and the increased nitrogen balance of 15 mg/kg/day were highly significant statistically. In addition a dose-response effect of alanine was observed. The effect of alanine was compared with that of a supplemental mixture of essential and non-essential amino acids, lacking only those considered to be toxic in these patients. Alanine at 0.05 g/kg was as effective in promoting growth in weight as 1.05 g/kg of the amino acid mixture, while 0.25 g/kg of alanine was more effective than 0.70 g/kg of the amino acid mixture. The protein sparing anabolic effect of alanine is thought to be a reflection of the alanine glucose cycle.

Studies on requirements for amino acids in infants with disorders of amino acid metabolism. I. Effect of alanine

Two infants with disorders of propionate metabolism were studied at 7 months of age to determine optimum levels of intake of protein and calories to meet the requirements for essential amino acid for growth in infancy, and at the same time minimize the accumulation of toxic intermediates. An effect of alanine was found that permitted growth at otherwise limiting levels of protein intake. This was not simply an effect of nonessential nitrogen as neither glycine nor glutamic acid could substitute for alanine in this protein-sparing effect. This appears to represent further evidence of the relationship between alanine and the branched-chain amino acids and of the importance of the alanine-glucose cycle in human physiology.

An evaluation of protein requirements in methylmalonic acidaemia

A 3-month-old girl and a 13-month-old boy with vitamin B12-unresponsive methylmalonic acidaemia were studied to determine responses to varying levels of protein intake of growth, nitrogen balance and organic acid metabolism. A linear increase in the excretion of methylmalonic acid was observed in both patients above a critical level of protein intake. The inflection point was judged to reflect a ceiling above which amino acid intake exceeded requirements and catabolism was initiated. Below this point in each infant there was a plateau of minimal excretion of methylmalonic acid. Within this plateau level a reasonable rate of growth and metabolic stability were achieved at intakes between 0.70 and 0.75 and between 0.75 and 1.17 g protein kg-1, respectively, indicating that there is a range of protein tolerance and the importance of an individual approach to the provision of protein in patients with methylmalonic acidaemia. In the 3-month-old infant, nitrogen equilibrium was achieved at protein intakes above 0.6 g kg-1 and modest nitrogen retention was attained at a protein intake of 0.75 g kg-1, a level at which the excretion of methylmalonic acid was minimal and weight gain satisfactory. A protein intake of 1.25 g kg-1 was required to achieve a level of nitrogen retention often considered optimal for normal growth; however, this infant demonstrated an elevated excretion of methylmalonic acid and was close to clinical illness at this level of protein intake. The 13-month-old infant demonstrated a normal level of nitrogen retention, minimal excretion of methylmalonic acid, and a satisfactory rate of growth at protein intakes of 1.0-1.17 g kg-1. The values should prove useful guidelines for the management of infants requiring minimal intakes of protein. In studies carried out at 18-20 months of age, supplementation of the basic diet containing 0.75 g kg protein-1 with a mixture of amino acids not containing the precursors of methylmalonic acid was associated with increase of retention of nitrogen and increased concentrations of some essential amino acids in plasma, but effects on growth and the excretion of methylmalonic acid were not significant.

Successful treatment of severe carbamyl phosphate synthetase I deficiency

We describe a girl with neonatal hyperammonaemia due to carbamyl phosphate synthetase I deficiency. Treatment consisted of protein restriction from the second day of life. Sodium benzoate was given for three weeks after birth and again from 7 months of age together with sodium phenylacetate to improve protein tolerance. Growth and development are normal at 15 months of age.

Tyrosinaemia II

Four cases of tyrosinaemia type II (Richner-Hanhart syndrome) are reported. This syndrome consists of corneal erosions, palmar and plantar hyperkeratoses, and sometimes mental retardation. Presentation with photophobia and dendritic corneal ulceration or circumscribed palmoplantar keratoderma should alert the physician to the possible diagnosis of tyrosinaemia II. Early diagnosis is important, as the clinical picture can be modified by dietary restriction.

Chronic vomiting in a case of citrullinaemia detected after treatment by total parenteral nutrition

We report a case of a 56 year old woman who presented with a long history of chronic attacks of vomiting. On admission to hospital she was cachectic, and attempted parenteral nutrition induced coma. The illness was found to be due to citrullinaemia, a metabolic disorder of the urea cycle. Our patient is the oldest with this disorder so far described in the literature. The main points of the case and its investigation are outlined: hyperammonaemia, amino acid chromatogram, measurement of enzyme activity in skin and liver biopsy material. The therapeutic measures which led to cure are of particular interest.

Tetrahydrobiopterin deficiencies: preliminary analysis from an international survey

Tetrahydrobiopterin deficiency is a rare cause of hyperphenylalaninemic syndromes. The natural history of the disease is characterized by progressive neurologic illness unresponsive to a phenylalanine-restricted diet. Fifty patients have been reported. From the documented cases, the following statements can be made: (1) An incidence of 2% among hyperphenylalaninemic babies can be reasonably estimated. (2) Most patients have high neonatal blood phenylalanine concentrations, but some have only mild elevations. (3) Among the available diagnostic tests, measurement of urine pteridines should be proposed in all hyperphenylalaninemic babies, (4) The tolerance to dietary phenylalanine is generally high. (5) The results of neurotransmitter replacement therapy are encouraging, but treatment should be started within the first month and requires a strict follow-up protocol. Consequently, in every newborn infant with positive Guthrie test results, a rapid investigation of BH4 metabolism should be accomplished in order to differentiate between phenylalanine-hydroxylase deficiencies (phenylketonuria, mild hyperphenylalaninemia, transient hyperphenylalaninemia) and BH4 deficiencies.

A successful trial of enzyme replacement therapy in a case of argininemia

A 5-year-old boy with severe mental retardation and spastic quadriplegia accompanied by tonic seizures and hyperammonemia was diagnosed as having argininemia due to an arginase deficiency in his erythrocytes. His motor and mental abilities began to deteriorate at the age of 3 years. Thereafter, he lost his ability to stand alone, to sit and even to crawl by himself. After he was diagnosed as argininemia , a protein restricted diet was given as therapy, which was accompanied with a supplement of essential amino acids. However, his clinical condition had not improved very much. The erythrocytes in a normal person was found to have the ability to decrease the patient's elevated plasma arginine level to normal when they are mixed in vitro. First we tried replacing his red cells by a blood transfusion. Then we replaced them with the aid of an IBM 2997 blood cell separator. Following this his clinical and biochemical condition improved, and as a result so did his sitting and crawling abilities. It appears that the replacement of red blood cells improves not only the clinical and biochemical conditions, but the general condition of the patient as well.

[Subacute citrullinemia--diagnosis and course up to 4th year of life]

The article reports on an infant which first in age of nine months and then again in age of 1.6 years had an episode of stupor. Laboratory investigation showed hyperammonemia and high values of transaminases. The differential diagnostic check up led to the diagnosis of citrullinemia in the age of 1.7 years by amino acid chromatography. The diagnosis could be confirmed by measuring enzyme activity in the liver. Therapy is protein-low feeding and supplementation of essential amino acids and arginine. A therapeutic trial with additional sodium benzoate did not show a positive effect. The patient made a significant step backwards in development during the second episode of stupor; however in the following months the retardation could be reduced markedly.

Hudson memorial lecture. Neonatal management of organic acidurias. Clinical update

Therapeutic guidelines have been obtained from a retrospective review of 41 patients affected with organic acidaemias, 16 patients with neonatal maple syrup urine disease (MSUD), 11 methylmalonic acidaemia, (MMA) seven propionic acidaemias (PA) and seven isovaleric acidaemias (IVA), and by comparing this personal series with similar reported cases. The emergency treatment of these organic acidurias in the neonate has to main goals: toxin removal and anabolism. Anabolism is always promoted by early diet therapy. The best method of toxin removal depends on the nature of the defect; peritoneal dialysis with exchange transfusions or multiple or prolonged exchange transfusions in MSUD and in PA, diuresis and exchange transfusions in MMA and glycine supplementation in IVA. Vitamin supplementation (thiamine 20 mg, biotin 10 mg, B12 2 mg and riboflavin 100 mg) should be tried in all cases although the neonatal forms of these defects are very rarely vitamin responsive. Additional treatments such as carnitine or insulin may prove to be useful.

Successful dietary control of tyrosinemia II

A Japanese girl, 2 years, 8 months of age, with palmoplantar keratosis and dendritic corneal opacities, showed increased tyrosine levels in the plasma, urine, and cerebrospinal fluid. The mental and physical growth was not retarded. The hepatorenal functions were within normal limits. Electron microscopically, the epidermal keratinocytes showed increased tonofibrils and no structures suggestive of tyrosine crystals. Cytosol and mitochondrial tyrosine aminotransferase (TAT) activities of the liver were greatly decreased, while p-hydroxyphenyl pyruvate oxidase (p-HPPO) activity was not decreased. The plasma tyrosine levels were controlled for 3 years with low phenylalanine-tyrosine diet.

Dietary therapy in a girl with propionic acidemia: supplement with leucine resulted in catch up growth

A 15-month-old girl with propionic acidemia presented a failure to thrive and muscular hypotonia, who had been treated with diets low in leucine, valine, isoleucine, threonine and methionine. Supplementation with leucine gave her a catch up growth and brought about an improvement in muscular hypotonia in parallel with restoration of plasma leucine which had been below normal range during the treatment with the above diets. Oral loading test of leucine produced no ketoacidosis. These findings indicate that the restriction of leucine is not necessary in the dietary management of propionic acidemia.

Histidinemia. A case with resolution of myoclonic seizures after treatment with a low-histidine diet

An infant with histidinemia had a myoclonic seizure disorder that was unresponsive to therapy with anticonvulsants. The seizures stopped promptly after a histidine-restricted diet was instituted. This case suggests that in some individuals with histidinemia, diet therapy may be effective. It is not known what distinguishes this case from previously reported cases in which diet therapy was not effective.

[A patient with persistent hyperlysinemia]

A 3 year old mentally retarded boy with convulsions and a disturbed motor, speech and social development is presented. A persistent hyperlysinaemia, lysinuria and saccharopinuria was found. Treatment with a diet restricted in lysine seems favourable.

[Methylmalonic aciduria. A case report]

A Black girl aged 19 months presented with vomiting, dehydration and severe acidosis without apparent cause. Further investigation revealed urinary excretion of large amounts of methylmalonic acid. The literature on methylmalonic aciduria is briefly reviewed. Seven possible biochemical defects have been described. Our patient did not improve with vitamin B12 therapy but the response after instituting a low-protein diet was excellent. The condition may be life-threatening if left untreated.

[Isovaleric acidemia: identical biochemical picture in 3 patients with variable clinical manifestations]

Three patients are described with different forms of isovaleric acidemia: a girl with the neonatal form and two brothers with an intermittent form. In all three patients the biochemical aspects are identical: Considerable amounts of metabolites of isovaleric acid, especially isovalerylglycine, are secreted with the urine. In the patients' cultured fibroblasts leucine oxydation is greatly depressed. The clinical presentation of the younger brother prompted to a direct search for a metabolic defect. After diagnosing an isovaleric acidemia in the younger brother, investigations on the presence of the same defect were performed in the elder brother too, though he did not show clinical symptoms. As a result, also isovaleric acidemia was found. It is concluded that sibs of patients with a proven inborn error of metabolism have to be studied too for the presence of the same defect. In all patients, especially in the girl with the neonatal form of isovaleric acidemia diet therapy had a beneficial effect on the further course of the disease.

Treatment of inborn errors of urea synthesis: activation of alternative pathways of waste nitrogen synthesis and excretion

Children with inborn errors of urea synthesis accumulate ammonium and other nitrogenous precursors of urea, leading to episodic coma and a high mortality rate. We used alternative pathways for the excretion of waste nitrogen as substitutes for the defective ureagenic pathways in 26 infants. These pathways involve synthesis and excretion of hippurate after sodium benzoate administration, and of citrulline and argininosuccinate after arginine supplementation. The children were treated for seven to 62 months; 22 survived. The mean plasma level of ammonium ( +/- S.E.) was 36 +/- 2 mumol per liter, and that of benzoate was 1.5 +/- 1.0 mg per deciliter. Alternative pathways accounted for between 28 and 59 per cent of the total "effective" excretion of waste nitrogen. Nineteen infants had normal height, weight, and head circumference, and 13 had normal intellectual development. Activation of alternative pathways of waste nitrogen excretion can prolong survival and improve clinical outcome in children with inborn errors of urea synthesis.

The effects of spacing protein intake on nitrogen balance and plasma amino acids in a child with propionic acidemia

The effect of protein distribution on nitrogen balance and the plasma aminogram was studied in a 34-month-old male child with propionic acidemia. Protein provided 4.8% of energy of which high biological value protein was given either as a bolus or evenly distributed in three meals per day. Analysis of nitrogen balance including estimated sweat nitrogen losses revealed no major difference between the two diets. No marked differences in the fasting plasma concentrations of essential amino acids were noted with protein distribution. A generalized increase in concentration of all nonessential amino acids except taurine and ornithine was noted when protein was evenly distributed throughout the day. The ratio of nonessential to essential amino acids was higher after even protein distribution than when protein was given as a bolus. The data suggests that a low protein diet (206 mg nitrogen/kg/day) with adequate energy intake used in managing this child with propionic acidemia provided adequate amounts of total nitrogen and essential amino acids for normal growth regardless of protein distribution.

Aminoacidopathies in Andhra Pradesh; report of a screening programme

A systematic and selective screening programme to detect disorders of amino acid metabolism was undertaken to gain insight into the incidence and prevalence of such disorders in the southern part of India. This region was selected due to the high incidence of consanguineous marriages. No earlier data were available. We based our study on mentally retarded children. We have attempted dietary therapy in two patients with phenylketonuria; the biochemical response in both cases was satisfactory. The highlight of this survey was the detection of a new metabolic defect, threoninaemia.

Gas-chromatographic/mass spectrometric detection of 3-hydroxy-3-methylglutaryl-CoA lyase deficiency in double first cousins

Gas chromatography/mass spectrometry was used for the detection of 3-hydroxy-3-methylglutaryl-CoA lyase (EC 4.1.3.4) deficiency in double first cousins. This enzyme is in the last step of leucine catabolism and is also involved in ketogenesis. Quantitation of urinary organic acids as their cyclohexyl esters demonstrated increased concentrations of 3-hydroxy-3-methylglutaric acid, 3-methylglutaconic acid, 3-methylglutaric acid, and 3-hydroxyisovaleric acid. The procedure is more rapid, sensitive, and specific than previously reported gas-chromatographic methods for acid quantitation. The affected children initially presented with symptoms similar to Reye's syndrome; the acids were quantitated during periods of altered intake of protein and fat. Both leucine and fat intake contributed to increased acid excretion. These studies suggest that life-threatening episodes of hypoglycemia are best prevented with a low-protein, low-fat diet.

The identification of (E)-2-methylglutaconic acid, a new isoleucine metabolite, in the urine of patients with beta-ketothiolase deficiency, propionic acidaemia and methylmalonic acidaemia

The identification of (E)-2-methylglutaconic acid, a 'new' metabolite of isoleucine, is described. The substance was detected in urine samples from patients with propionic acidaemia, methylmalonic acidaemia and so-called beta-ketothiolase deficiency; in the majority of cases together with N-tiglylglycine. (E)-2-Methylglutaconic acid is thought to be the end product of the 3-methylcrotonyl-CoA carboxylase-catalysed carboxylation of tiglyl-CoA. Prerequisites for the quantitative gas chromatographic analysis of the unstable 2- (and 3-) methyl-glutaconic acid ditrimethylsilyl ester are given.

Dietary treatment and biochemical studies on a neonatal case of propionyl-CoA carboxylase deficiency

The case of a patient with neonatal propionic acidaemia is reported. Despite an initially favourable response to the administration of an artificial formula, the patient finally died when 9.5 months old. Protein tolerance never exceeded 1.3 g kg-1 day-1. During the remission periods, when ingesting the formula, 3-hydroxypropionic acid was excreted alone or together with tiglylglycine and/or methylcitrate. In a period of ketoacidosis, in addition to these three metabolites and those of ketoacidosis, elevations of 2-methyl-3-oxovaleric acid, propionylglycine and 2-methyl-3-hydroxybutyric acid were found. A severe deficiency of propionyl-CoA carboxylase in cultured fibroblasts was detected; biotin, when added to the fibroblasts culture media, did not stimulate this enzyme activity. The effectiveness of the administered formula is discussed.

Treatment of hyperargininaemia due to arginase deficiency with a chemically defined diet

A brother and sister aged 11 and 17 years have been reported previously to have hyperargininaemia and arginase deficiency: they were treated with a semi-synthetic diet consisting of fat, carbohydrate, minerals, vitamins and essential amino acids in amounts equivalent to 0.55-0.65 g protein kg-1 day-1 for 2 years. Plasma arginine levels fell from 0.50-0.90 mumol/1 to 0.13-0.30 mumol/1 (normal range 0.02-0.15). Increased concentrations of arginine in the cerebrospinal fluid (CSF) fell from 0.069-0.098 mumol/l to 0.040-0.056 mumol/l (normal mean +/- SD = 0.020 +/- 0.006). Dibasic aminoaciduria returned to normal within 1 week. Substitution of the keto-acid analogues of five essential amino acids in the formula lowered arginine concentrations further, but proved to be unpalatable. Urinary concentrations of orotic acid, uridine and uracil fell toward normal but remained increased, even when the plasma ammonia concentration was measured as normal. Both patients showed a stable clinical improvement.