Outcome of maple syrup urine disease

1H-MR Spectroscopy of the Early Developmental Brain, Neonatal Encephalopathies, and Neurometabolic Disorders

MRI interpretations of the pediatric brain are often challenging for general radiologists and clinicians because MR  signals and morphology are continuously changing in the developing brain. Furthermore, the developing brain reacts differently to injuries, resulting in imaging characteristics that differ from those of the mature brain. Proton magnetic resonance spectroscopy (¹H-MRS) is a non-invasive method for assessing neurological abnormalities at the microscopic level and measures in vivo brain metabolites using a clinical MR machine. In MR examinations of the pediatric brain, ¹H-MRS demonstrates its powerful diagnostic capability when MRI is insufficient for diagnostic features. MRI and ¹H-MRS may be complementary tools for diagnosing and monitoring diseases. However, there is currently no consensus on how to include ¹H-MRS in clinical MR examinations. An overview of the clinical implementation of ¹H-MRS for the assessment of early pediatric developmental brains as well as the diagnosis, prognostification, and disease monitoring of various non-neoplastic brain disorders, including neonatal encephalopathies and neurometabolic/neurodegenerative diseases, was provided herein. Qualitative and quantitative ¹H-MRS is a powerful non-invasive tool for accessing various brain metabolites to confirm age appropriate peaks and detect abnormal peaks or deficient or reduced peaks, which may facilitate the identification of metabolic and neurodegenerative disorders as well as damage associated with hypoxic-ischemic encephalopathy (HIE). Moreover, ¹H-MRS has potential as a biomarker for monitoring therapeutic efficacy in metabolic diseases and neonatal HIE. It also provides insights into the pathophysiologies of various disorders, which may facilitate the use of novel therapeutic approaches. Therefore, ¹H-MRS needs to be included more frequently in routine clinical MR examinations of pediatric patients with neurological disorders.

Evaluation of Neonatal Acute Metabolic Crisis in Maple Syrup Urine Disease with MR Diffusion and MR Spectroscopy: Case Series and Review of the Literature

Magnetic resonance imaging (MRI) findings of acute metabolic crisis in maple syrup urine disease (MSUD) in neonates were reviewed. This case cohort study included six MSUD neonates imaged during acute metabolic decompensation. Specific diffusion imaging and proton spectroscopic findings were reviewed. All patients revealed extensive intramyelinic cytotoxic edema typically involving myelinated white matter structures. Brainstem, cerebellar white matter and peduncles, midbrain, posterior limbs of internal capsules, central portions of periventricular, and perirolandic white matter regions showed typical MSUD edema. Gray matter structures such as dentate nucleus and thalamus were involved in all patients. Involvement of other deep nuclei was also noted in a few patients. None of the patients showed involvement of the superficial cortex. Reduction in N-acetyl aspartate, a prominent lactate peak, and a peak representing methyl groups of amino acids were characteristic findings seen on intermediate short echo time MR spectroscopy. Our case series outlines the importance of diffusion and spectroscopy MR techniques in the diagnosis of acute neonatal MSUD metabolic crisis.

Neonatal hypertonia - a diagnostic challenge

In comparison to hypotonia, hypertonia is less commonly expressed in the neonatal period. The scientific literature on the causes of neonatal hypertonia is scant, with no suggested diagnostic algorithm easily available to clinicians. Aetiologies include conditions affecting the central nervous system and spine, and rare peripheral neuromuscular disorders leading to hypertonia. Aetiology onset may be antepartum, peripartum with either transient hypertonia or persistent hypertonia which may appear later, or from a postnatal event/disease. This review discusses neonatal hypertonia and a diagnostic approach to neonatal hypertonia is suggested.

Neonatal case of classic maple syrup urine disease: usefulness of (1) H-MRS in early diagnosis

We describe a male neonate with classic maple syrup urine disease (MSUD) in metabolic crisis. On day 7 of life, he was referred to hospital because of coma and metabolic acidosis with maple syrup odor. On day 4 after admission, brain magnetic resonance imaging findings were consistent with encephalopathy due to MSUD. Proton magnetic resonance spectroscopy ((1) H-MRS) showed a large methyl resonance peak at 0.9 p.p.m. The diagnosis of MSUD was confirmed on low branched-chain α-keto acid dehydrogenase complex activity in lymphocyte. (1) H-MR spectra were obtained in 10 min, while it took at least several days to obtain the results of other diagnostic examinations. In convalescence, the peak at 0.9 p.p.m. decreased. The large methyl resonance peak at 0.9 p.p.m. in brain (1) H-MRS would be one of the earliest clues to the diagnosis of classic MSUD in the neonatal period, especially in metabolic crisis.

Imaging in classic form of maple syrup urine disease: a rare metabolic central nervous system

Maple syrup urine disease (MSUD) is a rare autosomal recessive disorder of branched-chain amino acid metabolism. The condition gets its name from the distinctive sweet odour of affected infants’ urine. MSUD is caused by a deficiency of the branched-chain α-ketoacid dehydrogenase enzyme complex, leading to accumulation of the branched-chain amino acids (leucine, isoleucine, and valine) and their toxic by-products (ketoacids) in the blood and urine. Imaging is characterestized by MSUD oedema affecting the myelinated white matter. We present a neonate with classic type of MSUD and its imaging features on computed tomography, conventional magnetic resonance imaging, diffusion-weighted imaging, and magnetic resonance spectroscopy.

Neuroradiological findings in maple syrup urine disease

Maple syrup urine disease is a rare inborn error of amino acid metabolism involving catabolic pathway of the branched-chain amino acids. This disease, if left untreated, may cause damage to the brain and may even cause death. These patients typically present with distinctive maple syrup odour of sweat and urine. Patients typically present with skin and urine smelling like maple syrup. Here we describe a case with relevant magnetic resonance imaging findings and confirmatory biochemical findings.

Movement disorders in adult surviving patients with maple syrup urine disease

Maple syrup urine disease is a rare metabolic disorder caused by mutations in the branched-chain α-keto acid dehydrogenase complex gene. Patients generally present early in life with a toxic encephalopathy because of the accumulation of the branched-chain amino acids leucine, isoleucine, and valine and the corresponding ketoacids. Movement disorders in maple syrup urine disease have typically been described during decompensation episodes or at presentation in the context of a toxic encephalopathy, with complete resolution after appropriate dietary treatment. Movement disorders in patients surviving childhood are not well documented. We assessed 17 adult patients with maple syrup urine disease (mean age, 27.5 years) with a special focus on movement disorders. Twelve (70.6%) had a movement disorder on clinical examination, mainly tremor and dystonia or a combination of both. Parkinsonism and simple motor tics were also observed. Pyramidal signs were present in 11 patients (64.7%), and a spastic-dystonic gait was observed in 6 patients (35.2%). In summary, movement disorders are common in treated adult patients with maple syrup urine disease, and careful neurological examination is advisable to identify those who may benefit from specific therapy. © 2011 Movement Disorder Society.

Bloodspot acylcarnitine and amino acid analysis in cord blood samples: efficacy and reference data from a large cohort study

BACKGROUND

In order to test the feasibility of cord blood screening for inherited metabolic disease, a two-year cohort study of births in six obstetric units from five towns in the north of England was undertaken. These towns have a high prevalence of consanguineous marriages, largely among the immigrant Asian community. The purpose of the study was to determine whether early detection of metabolic disease was possible and whether early intervention would improve prognosis.

METHODS

Following parental consent, cord blood samples were collected at birth and analysed for acylcarnitine and amino acid profiles by tandem mass spectrometry in one of two laboratories. One laboratory used butylated derivatives, the other used underivatized samples. The same laboratories performed routine blood spot neonatal screening at 5-7 days of age on these babies. Patients with positive results were investigated and treated by a metabolic paediatrician as soon as possible.

RESULTS

24,983 births were examined. 12,952 samples were analysed as butyl derivatives, 12,031 samples were analysed underivatized. The following disorders were detected: medium-chain acyl-CoA dehydrogenase (MCAD) deficiency (1 case), 3-methylcrotonyl-CoA carboxylase (MCC) deficiency (2 cases), maternal carnitine transporter defect (2 cases), maternal MCC (1 case). The following disorders were diagnosed subsequently but were not detected by the cord blood screening: phenylketonuria (PKU) (1 case), maple syrup urine disease (MSUD) (2 cases), argininosuccinic aciduria (1 case), methylmalonic acidaemia (MMA) (1 case), glutaric aciduria type 2 (1 case), MCAD deficiency (2 cases), 3-hydroxy-3-methylglutaryl-CoA lyase deficiency (1 case). Comprehensive reference data for all analytes by both methods were obtained.

CONCLUSIONS

Cord blood testing is of limited value in detecting inherited metabolic disease. The metabolites associated with most disorders examined were not elevated in cord blood. Some maternal disorders, carnitine transporter defect and 3-methlycrotonyl-CoA carboxylase deficiency, are detected. These remain of uncertain clinical significance. Comprehensive reference data have been obtained that will facilitate future interpretation of studies in cord blood.

Synaptic plasma membrane Na(+), K (+)-ATPase activity is significantly reduced by the alpha-keto acids accumulating in maple syrup urine disease in rat cerebral cortex

The objective of the present study was to investigate the in vitro effects of the branched-chain alpha-keto acids accumulating in maple syrup urine disease, namely L-2-ketoisocaproic acid, L-2-keto-3-methylvaleric acid and L-2-ketoisovaleric acid on Na(+), K(+)-ATPase activity in synaptic plasma membranes from cerebral cortex of 35-day-old rats. All keto acids significantly inhibited Na(+), K(+)-ATPase activity at concentrations similar (1 mM) or even lower (0.5 mM) than those found in blood and cerebrospinal fluid of maple syrup urine disease patients. We also tested the effects of alanine on this enzyme activity. Alanine per se did not alter Na(+), K(+)-ATPase activity, but totally prevented the branched-chain alpha-keto acids-induced Na(+), K(+)-ATPase inhibition, indicating that alanine and the keto acids may possibly bind to the same site on the enzyme. We also observed that the branched-chain amino acids leucine, isoleucine and valine also inhibited Na(+) K(+)-ATPase activity to a similar degree as that of the branched-chain alpha-keto acids and that alanine was able to fully prevent these effects. Considering that Na(+), K(+)-ATPase is a critical enzyme for normal brain development and functioning, it is presumed that these findings may be involved in the pathophysiology of the neurological dysfunction of maple syrup urine disease.

Maple syrup urine disease: favourable effect of early diagnosis by newborn screening on the neonatal course of the disease

BACKGROUND

In the rare autosomal recessive disorder maple syrup urine disease (MSUD) the accumulation of the branched-chain amino acids and their metabolic products results in acute and chronic brain dysfunction. Since 2002, MSUD has been part of the extended newborn screening programme in Germany and Austria. Early diagnosis and intervention during the presymptomatic or early symptomatic period should improve the outcome of the patients, which would make the case for screening for MSUD.

AIM

The aim of the study was to evaluate the clinical course and alterations of marker metabolites during the first weeks of life in 10 patients with classical MSUD detected by newborn screening (NBS) in comparison with the 10 youngest German patients diagnosed clinically.

METHOD

Laboratory data as well as information on clinical course and management during the neonatal period were obtained retrospectively.

RESULTS

Patients detected in NBS presented with lower plasma leucine concentrations at confirmation of diagnosis and less severe clinical symptoms. Lowering of leucine to below a critical threshold of 1000 micromol/L was achieved earlier than in patients diagnosed on clinical grounds.

CONCLUSION

After diagnosis in screening, treatment can be initiated before the occurrence of severe metabolic decompensation. However, a favourable effect can only be achieved with immediate transfer of the neonate to a metabolic centre for adequate treatment in case of a positive screening result.

Comprehensive cost-utility analysis of newborn screening strategies

BACKGROUND

Inborn errors of metabolism are a significant cause of morbidity and death among children. Inconsistencies in how individual states arrive at screening strategies, however, lead to marked variations in testing between states.

OBJECTIVE

To determine the cost-effectiveness of each component test of a multitest newborn screening program, including screening for phenylketonuria, congenital adrenal hyperplasia, congenital hypothyroidism, biotinidase deficiency, maple syrup urine disease, galactosemia, homocystinuria, and medium-chain acyl-CoA dehydrogenase deficiency.

METHODS

A decision model was used, with cohort studies, government reports, secondary analyses, and other sources. Discounted costs, quality-adjusted life-years (QALYs), and incremental cost-effectiveness ratios were measured.

RESULTS

All except 2 screening tests dominated the "no-test" strategy. The 2 exceptions were screening for congenital adrenal hyperplasia, which cost slightly more than $20,000 per QALY gained, and screening for galactosemia, which cost $94,000 per QALY gained. The screening test with the lowest expected cost was tandem mass spectrometry. The results found in our base-case analysis were stable across variations in nearly all variables. In instances in which changes in risks, sequelae, costs, or utilities did affect our results, the variation from base-case estimates was quite large.

CONCLUSIONS

Newborn screening seems to be one of the rare health care interventions that is beneficial to patients and, in many cases, cost saving. Over the long term, funding comprehensive newborn screening programs is likely to save money for society.

Neuropsychometric outcome predictors for adults with maple syrup urine disease

We describe 14 adult MSUD patients (3 with intermediate MSUD) with varied clinical and neuropsychometric outcomes. Age at diagnosis appears to be a predictor of IQ even in adults, while long-term blood leucine does not correlate with IQ.

Diagnosis of MSUD by newborn screening allows early intervention without extraneous detoxification

Maple syrup urine disease (MSUD) is a genetic metabolic disorder resulting from the defective activity of branched-chain 2-ketoacid dehydrogenase complex. Due to the metabolic block, high concentrations of the branched-chain amino acids (BCAA) leucine, valine, isoleucine, and allo-isoleucine as well as their corresponding branched-chain 2-keto acids accumulate in patients on a BCAA-unrestricted diet or during episodes with increased protein catabolism. Early diagnosis and management are essential to prevent permanent brain damage. Newborn screening by tandem MS allows for detection of elevated BCAA concentrations in blood in patients with classical MSUD before they show severe encephalopathic symptoms. Here, we report that newborn screening by expanded tandem MS enables for reversing the intoxication in newborns with MSUD within 24-48 h without any need for extraneous detoxification and thus decreasing the risk of brain damage during a particularly vulnerable period.

Diagnosis and treatment of maple syrup disease: a study of 36 patients

OBJECTIVE

To evaluate an approach to the diagnosis and treatment of maple syrup disease (MSD).

METHODS

Family histories and molecular testing for the Y393N mutation of the E1alpha subunit of the branched-chain alpha-ketoacid dehydrogenase allow us to identify infants who were at high risk for MSD. Amino acid concentrations were measured in blood specimens from these at-risk infants between 12 and 24 hours of age. An additional 18 infants with MSD were diagnosed between 4 and 16 days of age because of metabolic illness. A treatment protocol for MSD was designed to 1) inhibit endogenous protein catabolism, 2) sustain protein synthesis, 3) prevent deficiencies of essential amino acids, and 4) maintain normal serum osmolarity. Our protocol emphasizes the enhancement of protein anabolism and dietary correction of imbalances in plasma amino acids rather than removal of leucine by dialysis or hemofiltration. During acute illnesses, the rate of decrease of the plasma leucine level was monitored as an index of net protein synthesis. The treatment protocol for acute illnesses included the use of mannitol, furosemide, and hypertonic saline to maintain or reestablish normal serum sodium and extracellular osmolarity and thereby prevent or reverse life-threatening cerebral edema. Similar principles were followed for both sick and well outpatient management, especially during the first year, when careful matching of branched-chain amino acid intake with rapidly changing growth rates was necessary. Branched-chain ketoacid excretion was monitored frequently at home and branched-chain amino acid levels were measured within the time of a routine clinic visit, allowing immediate diagnosis and treatment of metabolic derangements.

RESULTS

1) Eighteen neonates with MSD were identified in the high-risk group (n = 39) between 12 and 24 hours of age using amino acid analysis of plasma or whole blood collected on filter paper. The molar ratio of leucine to alanine in plasma ranged from 1.3 to 12.4, compared with a control range of 0.12 to 0.53. None of the infants identified before 3 days of age and managed by our treatment protocol became ill during the neonatal period, and 16 of the 18 were managed without hospitalization. 2) Using our treatment protocol, 18 additional infants who were biochemically intoxicated at the time of diagnosis recovered rapidly. In all infants, plasma leucine levels decreased to <400 micromol/L between 2 to 4 days after diagnosis. Rates of decrease of the plasma leucine level using a combination of enteral and parenteral nutrition were consistently higher than those reported for dialysis or hemoperfusion. Prevention of acute isoleucine, valine, and other plasma amino acid deficiencies by appropriate supplements allowed a sustained decrease of plasma leucine levels to the therapeutic range of 100 to 300 micromol/L, at which point dietary leucine was introduced. 3) Follow-up of the 36 infants over >219 patient years showed that, although common infections frequently cause loss of metabolic control, the overall rate of hospitalization after the neonatal period was only 0.56 days per patient per year of follow-up, and developmental outcomes were uniformly good. Four patients developed life-threatening cerebral edema as a consequence of metabolic intoxication induced by infection, but all recovered. These 4 patients each showed evidence that acutely decreased serum sodium concentration and decreased serum osmolarity were associated with rapid progression of cerebral edema during their acute illnesses.

CONCLUSIONS

Classical MSD can be managed to allow a benign neonatal course, normal growth and development, and low hospitalization rates. However, neurologic function may deteriorate rapidly at any age because of metabolic intoxication provoked by common infections and injuries. Effective management of the complex pathophysiology of this biochemical disorder requires integrated management of general medical care and nutrition, as well as control of several variables that influence endogenous protein anabolism and catabolism, plasma amino acid concentrations, and serum osmolarity.

Genetic screening of newborns

Screening of newborn infants for genetic disease began over 35 years ago as a public health measure to prevent mental retardation in phenylketonuria (PKU). It was so successful that tests for several other genetic disorders were added. We review the current status of this screening, including discussions of the genetic disorders often covered and the results of newborn screening for them. We emphasize recent advances. These include expansion of coverage for genetic disorders with the new methodology of tandem mass spectrometry (MS-MS) and the introduction of molecular (DNA) testing to increase the specificity of testing for several disorders, thereby reducing false-positive rates. These and other advances have also produced issues of criteria for screening, missed cases, and appropriate use of stored newborn specimens.

Is demyelination a feature of maple syrup urine disease?

To determine whether disturbance of myelination is a pathophysiologic feature in patients with treated maple syrup urine disease (MSUD), neurophysiologic studies were performed in 10 MSUD patients ages 4-16 years. Afferent and efferent pathways were studied by visual evoked potentials, somatosensory evoked potentials, motor evoked potentials, stance-stabilizing reflexes, and peripheral nerve conduction velocity. Magnetic resonance imaging was used to detect possible cerebral white matter abnormalities. Visual evoked potentials were normal in all patients. There was only slight prolongation of central afferent and efferent conduction times and the long latency component of the stance-stabilizing reflexes. Peripheral nerve conduction studies revealed reduced sensory nerve conduction velocity in 3 patients. The neurophysiologic findings were not consistently correlated to the neurologic outcome of the patients. Magnetic resonance imaging did not reveal major abnormalities and demonstrated bilateral periventricular high intensity periventricular signals on T2-weighted images in 4 of 10 patients. It is concluded that dysmyelination is not a major pathophysiologic feature in patients with MSUD.

Intellectual performance of children with maple syrup urine disease

The intellectual performance of 22 children aged 3-16 years with maple syrup urine disease (MSUD) was assessed and compared to a group of early treated phenylketonuria (PKU) children and normal subjects matched by age, sex, nationality, and socio-economic status. All subjects were tested by one examiner only using the age related versions of the non-verbal Snijders-Oomen intelligence test. The mean IQ (+/- SD) score was 74 +/- 14 (range 50-103) in patients with MSUD, 101 +/- 12 (range 87-125) in early treated PKU patients, and 107 +/- 9 (range 90-122) in normal subjects. Intercorrelations indicated that length of time after birth that plasma leucine concentration remained > 1 mmol/l and quality of long-term metabolic control have important influences on IQ.

Cerebral edema causing death in children with maple syrup urine disease

Four children with the classic form of maple syrup urine disease (MSUD) died of cerebral edema during an intercurrent infection that caused severe dehydration and acidosis. The diagnosis of MSUD had been established during the neonatal period in all four patients, on day 1 of life in three of them. All were in satisfactory control before the intercurrent illness. Two patients underwent peritoneal dialysis. Signs of brain-stem compression occurred after treatment, when biochemical abnormalities were improving. Computed tomography of the head, which was done in two patients, revealed cerebral edema; one of these patients also had subarachnoid hemorrhage. Autopsy in one case revealed cerebral edema with herniation. Our experience documents that cerebral edema may occur in the older child with MSUD as well as in the neonate. The pathogenesis of cerebral edema in MSUD remains unclear. Early treatment of dehydration and acidosis may prevent the catastrophic consequences that we have observed.

Intellectual outcome in children with maple syrup urine disease

We report a controlled study of intellectual outcome in 16 children with maple syrup urine disease (MSUD) that compares the outcome of MSUD diagnosed after symptoms became apparent with that of MSUD diagnosed prospectively and in unaffected siblings and parents. The mean IQ (+/- SD) score in the children with classic MSUD was 78 +/- 24; however, there were two discrete groups: one with normal IQ (greater than 84) whose MSUD had been diagnosed at a mean age of 3.5 days and a second group, with IQ below normal, whose MSUD was diagnosed at a mean of 10 days of age. Affected children treated presymptomatically had higher IQ scores than their affected siblings treated when their disease was symptomatic. Multiple regression analysis indicated that the important influences on IQ were age at the time of diagnosis and long-term metabolic control; control at the time of testing also might have affected performance. The mean score of unaffected siblings was 92 +/- 5 and the mean parental IQ was 83 +/- 9. The mean IQ scores of children with variant MSUD, 97 +/- 4, was similar to that of their parents, 103 +/- 6. This study was not longitudinal and thus could not identify subtle developmental learning problems. We conclude that early and meticulous treatment of MSUD can result in intellectually normal children.

Developmental profile of patients with maple syrup urine disease

The progress of nine maple syrup urine disease patients (eight classical, one possible variant) was reviewed to look for similarities in developmental patterns. A consistent developmental profile of stronger Verbal than Performance IQ and lower than familially expected IQ was seen. Younger age at diagnosis was associated with a milder neonatal course. Those who were asymptomatic or suffered mild complications in the newborn period have higher IQs than children experiencing moderate or severe complications. Children with asymptomatic or mild neonatal course also required less special education services. Overall, a picture of ubiquitous motor, visual-analytic and learning deficits is seen.

Ultrastructural findings in maple syrup urine disease in Poll Hereford calves

Ultrastructural findings in the nervous systems of two Poll Hereford calves affected with maple syrup urine disease or branched chain ketoacid decarboxylase deficiency are described. The calves were affected within 2 days of birth with a severe generalised central nervous system (CNS) disorder characterised by dullness and weakness, progressing to recumbency and opisthotonus. The urine had an odour of burnt sugar. Analysis of plasma and cerebrospinal fluid demonstrated significantly elevated levels of the branched chain amino acids leucine, isoleucine and valine. Status spongiosus affecting mainly the white matter was recorded at microscopic examination of the CNS, with ultrastructural examination confirming the presence of intramyelinic vacuole formation, suggesting myelin oedema.

[Leucinosis: study of a case]

Report of a case of Maple syrup urine disease in a female neonate, with diagnosis at 26th day of life. The neurological picture consisted of alternating periods of hyper with hypotonicity, seizures, lethargy, poor feeding and respiratory arrest. Demonstration of elevation of plasma branched-chain amino-acids, was the most widely available confirmatory test, and the therapy with MSUD resulted in improvement of the patient.

The management and long term outcome of organic acidaemias

We review the outcome of patients with maple syrup urine disease (14 classical patients and three variants), biotinidase deficiency (two patients) and non-cofactor-responsive variants of methylmalonic acidaemia (eight patients), propionic acidaemia (eight patients) and isolated 3-methylcrotonyl CoA carboxylase deficiency (three patients). Their survival, growth, intellectual development and other clinical problems are analysed. With the exception of isolated 3-methylcrotonyl CoA carboxylase deficiency the outcome of patients with disorders that are not cofactor responsive is disappointing. Twelve patients have died (five maple syrup urine disease, two methylmalonic acidaemia, five propionic acidaemia) and many of the survivors are developmentally retarded. The outlook is worst for patients with propionic acidaemia presenting in the neonatal period but a good outcome is possible for patients with maple syrup urine disease if the diagnosis is made early.

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.