Inborn errors of metabolism

We describe a liquid chromatography-tandem mass spectrometry assay for measurement of D-2-hydroxyglutaric acid and L-2-hydroxyglutaric acid. These metabolites are increased in specific inborn errors of metabolism and are now recognized as oncometabolites. The measurement of D-2-hydroxyglutarate in peripheral blood may be used as a biomarker for screening and follow-up of patients with IDH-mutated acute myeloid leukemia.

Alkaline phosphatase can be considered "our favorite enzyme" for reasons apparent to those who diagnose and treat metabolic bone diseases or who study skeletal biology. Few might know, however, that alkaline phosphatase likely represents the most frequently assayed enzyme in all of Medicine. Elevated activity in the circulation is universally recognized as a marker for skeletal or hepatobiliary disease. Nevertheless, the assay conditions in many ways are non-physiological. The term alkaline phosphatase emerged when it became necessary to distinguish "bone phosphatase" from the phosphatase in the prostate that features an acidic pH optimum...

PurposeRecognizing individuals with inherited diseases can be difficult because signs and symptoms often overlap those of common medical conditions. Focusing on inborn errors of metabolism (IEMs), we present a method that brings the knowledge of highly specialized experts to professionals involved in early diagnoses. We introduce IEMbase, an online expert-curated IEM knowledge base combined with a prototype diagnosis support (mini-expert) system.MethodsDisease-characterizing profiles of specific biochemical markers and clinical symptoms were extracted from an expert-compiled IEM database...

Congenital disorders of glycosylation (CDG) are inborn errors of metabolism due to protein and lipid hypoglycosylation. This rapidly growing family of genetic diseases comprises 103 CDG types, with a broad phenotypic diversity ranging from mild to severe poly-organ -system dysfunction. This literature review summarizes cardiac involvement, reported in 20% of CDG. CDG with cardiac involvement were divided according to the associated type of glycosylation: N-glycosylation, O-glycosylation, dolichol synthesis, glycosylphosphatidylinositol (GPI)-anchor biosynthesis, COG complex, V-ATPase complex, and other glycosylation pathways...

Adult onset urea cycle disorders (UCD) may present with psychiatric symptoms, occasionally as the initial presentation. We aimed to describe the characteristics of patients presenting with a psychiatric adult-onset of UCDs, to discuss which signs could suggest this diagnosis in such a situation, and to determine which tests should be conducted. A survey of psychiatric symptoms occurring in teenagers or adults with UCD was conducted in 2010 among clinicians involved in the French society for the study of inborn errors of metabolism (SFEIM)...

BACKGROUND: Most inborn errors of metabolism result in mental retardation and death due to accumulation of abnormal metabolites in the tissues. The presence of abnormal metabolites in the urine of mentally retarded individuals has been used worldwide for detection of inborn errors of metabolism. The purpose of the study is to determine the prevalence of inborn error of metabolism in mentally retarded children. METHODS: Random urine samples were collected from mentally retarded children at two institutes in Kathmandu, and also from 60 normal children from Duwakot, Nepal after obtaining consent from their parents...

Phenylketonuria (PKU) is an inborn error of phenylalanine metabolism due to mutations in phenylalanine hydroxylase (PAH). Recently, small compounds, known as pharmacological chaperones (PhCs), have been identified that restore the enzymatic activity of mutant PAHs. Understanding the mechanism of the reduction in enzymatic activity due to a point mutation in PAH and its restoration by PhC binding is important for the design of more effective PhC drugs. Thermal fluctuations of an enzyme can alter its activity...

2-methylacetoacetyl-coenzyme A thiolase (MAT) deficiency, also known as beta-ketothiolase deficiency, is an inborn error of ketone body utilization and isoleucine catabolism. It is caused by mutations in the ACAT1 gene and may present with metabolic ketoacidosis. In order to obtain a more comprehensive view on this disease, we have collected clinical and biochemical data as well as information on ACAT1 mutations of 32 patients from 12 metabolic centers in five countries. Patients were between 23months and 27years old, more than half of them were offspring of a consanguineous union...

BACKGROUND: Familial hypercholesterolemia is one of the most common inherited metabolic diseases and is an autosomal dominant disorder meaning heterozygotes, or carriers, are affected. Those who are homozygous have severe disease. The average worldwide prevalence of heterozygous familial hypercholesterolemia is at least 1 in 500, although recent genetic epidemiological data from Denmark and next generation sequencing data suggest the frequency may be closer to 1 in 250. Diagnosis of familial hypercholesterolemia in children is based on elevated total cholesterol and low-density lipoprotein cholesterol levels or DNA-based analysis, or both...

A combination of unexplained peripheral neuropathy, hypoparathyroidism, and the inability to cope with metabolic stress could point to a rare inborn error of metabolism, such as mitochondrial trifunctional protein (MTP) deficiency.Here, we describe a 20-year-old woman who was known since childhood with axonal motor sensory polyneuropathy of unknown origin. She presented with progressive dyspnoea, and increased muscle weakness, preceded by 6 days of fever, vomiting, and diarrhoea. Laboratory testing showed rhabdomyolysis, and hypocalcaemia with low parathyroid levels...

Phenylketonuria (PKU), one of the most common inborn errors of amino acid metabolism, is caused by mutations in the phenylalanine hydroxylase (PAH) gene (PAH). PKU has wide allelic heterogeneity, and over 600 different disease-causing mutations in PAH have been detected to date. Up to now, there have been no reports on the minihaplotype (VNTR/STR) analysis of PAH locus in the Iranian population. The aims of the present study were to determine PAH mutations and minihaplotypes in Iranian families with PAH deficiency and to investigate the correlation between them...

Metabolomics can be described as a simultaneous and comprehensive analysis of small molecules in a biological sample. Recent technological and bioinformatics advances have facilitated large-scale metabolomic studies in many areas, including inborn errors of metabolism (IEMs). Despite significant improvements in the diagnosis and treatment of some IEMs, it is still challenging to understand how genetic variation affects disease progression and susceptibility. In addition, a search for new more personalized therapies and a growing demand for tools to monitor the long-term metabolic effects of existing therapies set the stage for metabolomics integration in preclinical and clinical studies...

Inborn errors of metabolism (IEM) are a rare cause of epilepsy, but seizures and epilepsy are frequently encountered in patients with IEM. Since these disorders are related to inherited enzyme deficiencies with resulting effects on metabolic/biochemical pathways, the term "metabolic epilepsy" can be used to include these conditions. These epilepsies can present across the life span, and share features of refractoriness to anti-epileptic drugs, and are often associated with co-morbid developmental delay/regression, intellectual, and behavioral impairments...

BACKGROUND: Tyrosine Hydroxylase deficiency is a rare neurotransmitter disorder. CASE CHARACTERISTICS: An Indian family with the disorder. OBSERVATIONS: Phenotypic variation, elevated serum prolactin, genetic confirmation, and partial treatment-responsiveness. MESSAGE: Tyrosine Hydroxylase deficiency is a treatable inborn error of metabolism and serum prolactin assists in diagnosis.

Metabolic decompensation in inborn errors of metabolism (IEM) is characterized by a rapid deterioration in metabolic status leading to life-threatening biochemical perturbations (e.g. hypoglycemia, hyperammonemia, acidosis, organ failure). Infection is the major cause of metabolic decompensation in patients with IEM. We hypothesized that activation of the immune system during infection leads to further perturbations in end-organ metabolism resulting in increased morbidity. To address this, we established model systems of metabolic decompensation due to infection...

Multiple endocrine neoplasia (MEN1) is a rare autosomal dominant disorder characterized by primary hyperparathyroidism, enteropancreatic neuroendocrine tumors, and anterior pituitary adenomas. A 16-year-old male presented to the emergency outpatient clinic with tonic convulsions. Physical examination in the postconvulsive period was unremarkable and revealed a muscular, postpubertal adolescent. Biochemical tests at admission were consistent with hyperinsulinemic hypoglycemia and remarkable for elevated levels of liver transaminases and creatine kinase...

PurposeTesting for inborn errors of metabolism is performed by clinical laboratories worldwide, each utilizing laboratory-developed procedures. We sought to summarize performance in the College of American Pathologists' (CAP) proficiency testing (PT) program and identify opportunities for improving laboratory quality. When evaluating PT data, we focused on a subset of laboratories that have participated in at least one survey since 2010.MethodsAn analysis of laboratory performance (2004 to 2014) on the Biochemical Genetics PT Surveys, a program administered by CAP and the American College of Medical Genetics and Genomics...

In recent years the number of disorders known to affect amino acid synthesis has grown rapidly. Nor is it just the number of disorders that has increased: the associated clinical phenotypes have also expanded spectacularly, primarily due to the advances of next generation sequencing diagnostics. In contrast to the "classical" inborn errors of metabolism in catabolic pathways, in which elevated levels of metabolites are easily detected in body fluids, synthesis defects present with low values of metabolites or, confusingly, even completely normal levels of amino acids...

Propionic acidemia (PA) is an inborn error of protein metabolism with a variable clinical presentation ranging from neonatal encephalopathy to seemingly asymptomatic individuals who present with cardiomyopathy or sudden death. PA is recognized in the Amish population, often with an early asymptomatic course and eventual cardiac complications. Thus, Amish women with PA may reach reproductive age without clinical sequelae, but are at increased risk for metabolic decompensation during pregnancy, delivery and postpartum period...

Epileptic encephalopathies represent a particularly severe form of epilepsy, associated with cognitive and behavioral deficits, including impaired social-communication and restricted, repetitive behaviors that are the hallmarks of autism spectrum disorder (ASD). With the advent of next-generation sequencing, the genetic landscape of epileptic encephalopathies is growing and demonstrates overlap with genes separately implicated in ASD. However, many questions remain about this connection, including whether epileptiform activity itself contributes to the development of ASD symptomatology...