Carnosinase, diabetes mellitus and the potential relevance of carnosinase deficiency.

Carnosinase (CN1) is a dipeptidase, encoded by the CNDP1 gene, that degrades histidine-containing dipeptides, such as carnosine, anserine and homocarnosine. Loss of CN1 function (also called carnosinase deficiency or aminoacyl-histidine dipeptidase deficiency) has been reported in a small number of patients with highly elevated blood carnosine concentrations, denoted carnosinaemia; it is unclear whether the variety of clinical symptoms in these individuals is causally related to carnosinase deficiency. Reduced CN1 function should increase serum carnosine concentrations but the genetic basis of carnosinaemia has not been formally confirmed to be due to CNDP1 mutations. A CNDP1 polymorphism associated with low CN1 activity correlates with significantly reduced risk for diabetic nephropathy, especially in women with type 2 diabetes, and may slow progression of chronic kidney disease in children with glomerulonephritis. Studies in rodents demonstrate antiproteinuric and vasculoprotective effects of carnosine, the precise molecular mechanisms, however, are still incompletely understood. Thus, carnosinemia due to CN1 deficiency may be a non-disease; in contrast, carnosine may potentially protect against long-term sequelae of reactive metabolites accumulating, e.g. in diabetes and chronic renal failure.

Diagnostic methods and recommendations for the cerebral creatine deficiency syndromes.

Primary care pediatricians and a variety of specialist physicians strive to define an accurate diagnosis for children presenting with impairment of expressive speech and delay in achieving developmental milestones. Within the past two decades, a group of disorders featuring this presentation have been identified as cerebral creatine deficiency syndromes (CCDS). Patients with these disorders were initially discerned using proton magnetic resonance spectroscopy of the brain within a magnetic resonance imaging (MRI) examination. The objective of this review is to provide the clinician with an overview of the current information available on identifying and treating these conditions. We explain the salient features of creatine metabolism, synthesis, and transport required for normal development. We propose diagnostic approaches for confirming a CCDS diagnosis. Finally, we describe treatment approaches for managing patients with these conditions.

[Succinic semialdehyde dehydrogenase deficiency: an inheritable neurometabolic disease]. / Succinat-Semialdehyd-Dehydrogenase-Mangel: eine vererbbare neurometabolische Erkrankung.

Succinic semialdehyde dehydrognase deficiency (SSADHD) is a neurometabolic disease with autosomal recessive inheritance. Although only about 450 cases are known worldwide, SSADHD is a frequent paediatric disorder of the neurotransmitter metabolism. SSADHD is caused by a mutation of the Aldh5a1-gene resulting in a dysfunction of the enzyme succinic semialdehyde dehydrogenase. This is followed by an accumulation of γ-aminobutyric acid and succinic semialdehyde that is alternatively metabolised via succinic semialdehyde reductase to γ-hydroxybutyric acid. The clinical phenotype is unspecific with pronounced interindividual variability. However, delayed acquisition of motor and language developmental milestones as well as epilepsy, mental retardation, sleep disorder, ataxia, muscle hypotonia, and behavioural disturbances are frequent. First symptoms frequently occur in the first year of life while the general course of the disease is non-progressive. Currently, no causal therapy exists.

The screening of SLC6A8 deficiency among Estonian families with X-linked mental retardation.

The urinary creatine:creatinine (Cr:Crn) ratio was measured in males from 49 families with a family history compatible with X-linked mental retardation (XLMR) in order to estimate the prevalence of SLC6A8 deficiency in Estonia. We identified 11 boys from 9 families with an increased urinary Cr:Crn ratio (18%). In three related boys, a hemizygous missense mutation (c.1271G>A; p.Gly424Asp) was identified. Their mother was heterozygous for the same mutation. Although many missense mutations have been described, the p.Gly424Asp mutation has not been previously reported. The clinical expression varied widely among affected males of this family. Patients 1 and 3 had relatively mild clinical expression (mild mental retardation (MR) and attention deficit disorder), but patient 2 had all typical clinical signs of SLC6A8 defect such as moderate MR, autistic features, expressive dysphasia and epilepsy. Among our patients, we saw significant problems in speech and language development combined with attention and behavioural difficulties. The number of false-positive biochemical results with increased urinary Cr:Crn ratio was higher (18%) in our study than in previous reports (1.8­10%). We therefore suggest that repeated biochemical testing should be performed before DNA sequencing analysis. Our study suggests that 2% (95% confidence limits: 0.05­11.1%) of this Estonian XLMR panel are due to mutations in the SLC6A8, which is similar to the prevalence reported in other populations. We therefore conclude that creatine transporter deficiency is a relatively common genetic disorder in males with sporadic or familiar MR and diagnostic screening of them should always include screening for SLC6A8 deficiency.

Monogenic Mendelian disorders in general neurological practice.

An observational study of monogenic Mendelian disorders seen in general neurology outpatient clinics over a 6-year period was undertaken. Fifty-three patients with 16 different diagnoses were identified, the commonest being Huntington's disease and neurofibromatosis type 1. This low frequency of monogenic Mendelian disorders has implications for both continuing medical education and for neurological training. All such patients are probably best referred to specialist clinics where expertise in diagnosis, genetic counselling and testing, and management has been developed.

[Autism and metabolic disorders-a rational approach]. / Autismus und Stoffwechselerkrankungen--was ist gesichert?

The causes of autism are heterogeneous and predominantly genetically determined. An exact aetiology is found in less than 10% of affected patients. The disappointment about low rates of success in identifying a definite pathology, numerous reports about the association of autism and "metabolic derangements", and rumours of "miraculous cures" after application of various drugs and dietary regimes have resulted in substantial confusion about meaningful diagnostic procedures and rational therapies for subjects with autism. The aim of this report is to give an overview about rare, genetically determined neurometabolic disorders (inborn errors of metabolism) that are evidently (e.g. Smith-Lemli-Opitz Syndrome) or allegedly (e.g. succinate semialdehyde dehydrogenase deficiency) associated with autism-specific symptoms. Affected patients usually display additional neurological symptoms. Procedures required to establish the diagnosis and eventual therapeutic consequences derived from a specific metabolic defect are presented. In addition to these well-defined neurometabolic disorders for which there are rational therapeutic strategies, hypotheses about the association of autism with "metabolic derangements" that could not be confirmed or were clearly falsified are discussed.

[Epidemiological and clinical study of West syndrome in Nagasaki Prefecture, Japan].

To determine the occurrence, outcome, and prognostic factors of West syndrome (WS), we performed a retrospective epidemiological study of WS occurred in 47 children (26 boys and 21 girls) in Nagasaki prefecture during a recent 10-year period from 1989 to 1998. The incidence of WS was 3.1/10,000 live births. The mean age at onset of spasm is 6.3 months (range: 2 to 12 months). Thirty-nine patients (83%) had symptomatic WS, in which the prenatal causes (patients) were most frequent, followed by low-birth weight infants (patients), perinatal (patients) and postnatal (patients). The brain CT was performed in 37 patients, and revealed congenital brain malformations (9 patients), destructive brain disorders (12 patients), and no structural abnormalities (16 patients). The seizure outcome was worse in the symptomatic WS than in the cryptogenic WS; seizure/disappeared in 39% of the former and in 75% of the latter/developmental delay before the onset of WS, relapse of WS and persistence of seizures were associated with poor seizure outcomes. Among the remaining seizures at the time of this surveillance, a tonic seizure was most frequently observed, followed by the partial seizures. Lennox-Gastaut syndrome was observed in 2 patients only. Epileptic discharge in the latest interictal EEG were diffuse in 4.3%, focal or multifocal in 60.7%, and absent in 35%, suggesting that many patients with WS had cortical epileptogenic foci. The developmental outcome was very poor in both the symptomatic and cryptogenic WS. The mean DQ in all the patients was 25, and only 4 patients (11%) had a normal DQ (> 75). DQ was lower in patients with congenital brain malformations than in those with destructive brain disorders.

Cerebral neoplasms in L-2 hydroxyglutaric aciduria: 3 new cases and meta-analysis of literature data.

SUMMARY: Increasing evidence suggests that patients with L2-HGA have a predisposition to cerebral neoplasms. This may be related to the pathologic accumulation of L2-HG because high amounts of 2-HG have been found in brain neoplasms that have IDH1 mutations. Our experience, on the basis of 11 previously unreported cases of L2-HGA, 3 of which developed cerebral neoplasms during the course of the disease, also supports an association between L2-HGA and cerebral neoplasms. We conducted a meta-analysis of published data, and we identified 295 patients (including our 11 patients) with L2-HGA. In 14 patients, the metabolic disorder was associated with cerebral neoplasms, suggesting an approximately 5% prevalence rate of CNS neoplasms in patients with L2-HGA; nonetheless, it may still be an underestimate. L2-HGA is an important disease "model" that provides further evidence to support the recently proposed pathogenetic role of 2-HG in the development of cerebral neoplasms.

Urgencias metabólicas y genéticas en la Unidad de Recién Nacidos: enfermedad de la orina con olor a jarabe de arce / Genetic and metabolic urgencies in the neonatal intensive care unit: maple syrup urine disease

La enfermedad de la orina con olor a jarabe de arce (EOJA) es un trastorno hereditario del metabolismo de aminoácidos ramificados causada por mutaciones en el complejo mitocondrial Deshidrogenasa de Cetoácidos de Cadena Ramificada (BCKDH). La disfunción de este complejo genera la acumulación tóxica de aminoácidos de cadena ramificada (BCAA), lo que conlleva un especial impacto en el sistema nervioso central. La acumulación de sustratos provoca encefalopatía aguda neonatal severa, rápidamente progresiva y catastrófica si no se instaura a tiempo el tratamiento. Esta entidad tiene un manejo médico específico en fase aguda y un tratamiento a largo plazo para evitar secuelas y mortalidad. De ahí la importancia de tenerla en cuenta como diagnóstico diferencial. Se presenta a continuación un caso colombiano de un paciente con EOJA de presentación clásica neonatal con desenlace fatal, como ejemplo de urgencia metabólica y diagnóstico diferencial en un neonato encefalopático (AU)

Maple syrup urine disease (MSUD) is a hereditary disorder of branched chain amino/keto acid metabolism, caused by a decreased activity of the branched-chain alpha-ketoacid dehydrogenase complex (BCKAD), which leads to abnormal elevated plasma concentrations of branched-chain amino acids (BCAAs) clinically manifested as a heavy burden for Central Nervous system. The toxic accumulation of substrates promotes the development of a severe and rapidly progressive neonatal encephalopathy if treatment is not immediately given. This disorder has a specific medical management in acute phase in order to minimize mortality and morbidity. For all those reasons, it is important to include the MSUD as a possible diagnosis in a encephalopathic newborn. We present a colombian newborn with classical MSUD with fatal outcome as an example of metabolic emergency and a differential diagnosis in the encephalopathic newborn (AU)

CP or not CP? A review of diagnoses in a cerebral palsy register.

The purpose of this study was to document the inaccuracy rate of diagnosis of cerebral palsy recorded on the South Australian Cerebral Palsy Register. A total of 402 children born in South Australia from 1993 to 2002 and notified to the Register as having cerebral palsy were identified through the Register database, and 21 children (5.2%) were later identified to have a noncerebral palsy diagnosis. Of these, 5 had either a metabolic or a neurodegenerative disorder and 2 had a syndromic disorder (1 Joubert syndrome and 1 Sotos syndrome); the remaining 14 children had one of the following final diagnoses: developmental delay, gross motor delay, perinatal myositis, spinal subdural and subarachnoid arteriovenous malformation, and Erb's palsy. In 16 of 21 children (76%), the diagnosis was changed at 5 years of age or older. Studies based on population registers may need to take into account the possibility of misclassification, estimated to be at least 5.2% in this study. A complete clinical assessment at the time of diagnosis followed by regular reassessment would enable the clinician to exclude children with alternative diagnoses, which has important implications for clinical management and research based on cerebral palsy registers.

Frequencies of inherited organic acidurias and disorders of mitochondrial fatty acid transport and oxidation in Germany.

UNLABELLED: The lack of epidemiological data on the frequency and/or burden of organic acidurias (OA) and mitochondrial fatty acid transport and oxidation disorders (mtFATOD) is one reason for hesitation to expand newborn screening (NBS) by tandem mass spectrometry (MS-MS). From 1999 to 2000, the frequency of ten potentially treatable OA and mtFATOD was assessed by active nation-wide surveillance on cases presenting with clinical symptoms using the German Paediatric Surveillance Unit (ESPED) system. Case ascertainment was complemented by a second independent source: 3-monthly inquiries in the metabolic laboratories performing secondary selected screening for OA and mtFATOD. Frequency estimates for clinically symptomatic cases older than 7 days in a birth cohort of 844,575 conventionally screened children was compared to the frequency found in a cohort of 382,247 screened by MS-MS in Bavaria and Baden-Württemberg. The overall frequency of the ten conditions considered was 1:8,000 (95% CI 1:11,000-1:6,000) by MS-MS as compared to 1:23,000 (95% CI 1:36,000-1:17,000) in symptomatic cases presenting mainly with metabolic crisis. The contributions of medium-chain acyl-CoA dehydrogenase deficiency (MCADD), other mtFATOD and OA were 29, 4 and 13 among the 46 cases identified by MS-MS, and 19, 1 and 13 among the 33 clinically symptomatic cases, respectively. Acute metabolic crisis, with a lethal outcome in four patients, was reported for 22/33 clinically symptomatic cases. No clinically symptomatic cases were reported from cohorts with screened by MS-MS. CONCLUSION: ten potentially treatable organic acidurias and mitochondrial fatty acid transport and oxidations disorders were more common than phenylketonuria with organic acidurias accounting for 28% of the cases detected by newborn screening and 39% of the cases identified on high risk screening. These conditions were related to considerable morbidity and mortality. Considerations for their inclusion in expanded newborn screening programmes might be warranted.

Enfermedades neurometabólicas: orientación para el neuropediatra / Neurometabolic diseases: Guidance for neuropaediatricians

Introducción y desarrollo. Las enfermedades neurometabólicas constituyen un área compleja y en constante expansión. Si bien inicialmente consideradas como rarezas o curiosidades médicas, su crecimiento continuo y desarrollo hacen que, en la actualidad, tomen una relevancia especial por razones diversas. Por un lado permitirán que comprendamos mejor los mecanismos de enfermedad neurológica; por otra parte, desde un punto de vista clínico, se presentan de manera heterogéneay con frecuencia mediante síntomas muy prevalentes en neuropediatría como pueden ser la ataxia, el retraso mental o la epilepsia.Conclusiones. Poco a poco, el neurometabolismo nos ofrece un lenguaje a través del cual descifrar la fisiopatología de las enfermedades neurológicas independientemente de su causa. Todo esto hace que el neuropediatra necesite una formación continua y unas guías básicas a través de las cuales afrontar en la actividad clínica estos trastornos. Este artículo pretende dar una orientación práctica en este sentido

Introduction and development. Neurometabolic diseases constitute an area that is both complex and in constantgrowth. Although they were initially seen as rarities or medical curiosities, their continuous growth and development means that today they have become especially relevant for a number of reasons. On the one hand, they will provide us with a better understanding of the mechanisms involved in neurological diseases, while on the other, their clinical presentation is heterogeneousand often takes the form of symptoms that are highly prevalent in neuropaediatrics, such as ataxia, mental retardation or epilepsy. Conclusions. Little by little, neurometabolism is providing us with a language that will make it possible to decipher the pathophysiology of neurological diseases regardless of their causation. All this means that neuropaediatricians require permanent education and a set of basic guidelines that can be used to deal with these disorders in clinical practice. The purpose of this paper is to give practical guidance in this sense