scholarly journals Second-Tier Test for Quantification of Alloisoleucine and Branched-Chain Amino Acids in Dried Blood Spots to Improve Newborn Screening for Maple Syrup Urine Disease (MSUD)

2008 ◽  
Vol 54 (3) ◽  
pp. 542-549 ◽  
Author(s):  
Devin Oglesbee ◽  
Karen A Sanders ◽  
Jean M Lacey ◽  
Mark J Magera ◽  
Bruno Casetta ◽  
...  
Keyword(s):  
Amino Acids ◽  
Newborn Screening ◽  
Dried Blood Spots ◽  
Branched Chain Amino Acids ◽  
Maple Syrup ◽  
Blood Spots ◽  
Urine Disease ◽  
Second Tier ◽  
Branched Chain ◽  
Positive Results

Abstract Background: Newborn screening for maple syrup urine disease (MSUD) relies on finding increased concentrations of the branched-chain amino acids (BCAAs) leucine, isoleucine, and valine by tandem mass spectrometry (MS/MS). d-Alloisoleucine (allo-Ile) is the only pathognomonic marker of MSUD, but it cannot be identified by existing screening methods because it is not differentiated from isobaric amino acids. Furthermore, newborns receiving total parenteral nutrition often have increased concentrations of BCAAs. To improve the specificity of newborn screening for MSUD and to reduce the number of diet-related false-positive results, we developed a LC-MS/MS method for quantifying allo-Ile. Methods: Allo-Ile and other BCAAs were extracted from a 3/16-inch dried blood spot punch with methanol/H2O, dried under nitrogen, and reconstituted into mobile phase. Quantitative LC-MS/MS analysis of allo-Ile, its isomers, and isotopically labeled internal standards was achieved within 15 min. To determine a reference interval for BCAAs including allo-Ile, we analyzed 541 dried blood spots. We also measured allo-Ile in blinded samples from 16 MSUD patients and 21 controls and compared results to an HPLC method. Results: Intra- and interassay imprecision (mean CVs) for allo-Ile, leucine, isoleucine, and valine ranged from 1.8% to 7.4%, and recovery ranged from 91% to 129%. All 16 MSUD patients were correctly identified. Conclusions: The LC-MS/MS method can reliably measure allo-Ile in dried blood spots for the diagnosis of MSUD. Applied to newborn screening as a second-tier test, it will reduce false-positive results, which produce family anxiety and increase follow-up costs. The assay also appears suitable for use in monitoring treatment of MSUD patients.

scholarly journals Brain Branched-Chain Amino Acids in Maple Syrup Urine Disease: Implications for Neurological Disorders

2020 ◽  
Vol 21 (20) ◽  
pp. 7490
Author(s):  
Jing Xu ◽  
Youseff Jakher ◽  
Rebecca C. Ahrens-Nicklas
Keyword(s):  
Amino Acids ◽  
Maple Syrup Urine Disease ◽  
Attention Deficit Disorder ◽  
Neurological Disorders ◽  
Survival Rates ◽  
Branched Chain Amino Acids ◽  
Maple Syrup ◽  
Urine Disease ◽  
Branched Chain ◽  
The Brain

Maple syrup urine disease (MSUD) is an autosomal recessive disorder caused by decreased activity of the branched-chain α-ketoacid dehydrogenase complex (BCKDC), which catalyzes the irreversible catabolism of branched-chain amino acids (BCAAs). Current management of this BCAA dyshomeostasis consists of dietary restriction of BCAAs and liver transplantation, which aims to partially restore functional BCKDC activity in the periphery. These treatments improve the circulating levels of BCAAs and significantly increase survival rates in MSUD patients. However, significant cognitive and psychiatric morbidities remain. Specifically, patients are at a higher lifetime risk for cognitive impairments, mood and anxiety disorders (depression, anxiety, and panic disorder), and attention deficit disorder. Recent literature suggests that the neurological sequelae may be due to the brain-specific roles of BCAAs. This review will focus on the derangements of BCAAs observed in the brain of MSUD patients and will explore the potential mechanisms driving neurologic dysfunction. Finally, we will discuss recent evidence that implicates the relevance of BCAA metabolism in other neurological disorders. An understanding of the role of BCAAs in the central nervous system may facilitate future identification of novel therapeutic approaches in MSUD and a broad range of neurological disorders.

scholarly journals Skin Lesions Associated with Dietary Management of Maple Syrup Urine Disease: a Case Report

2015 ◽  
Vol 7 (4) ◽  
pp. 153-162 ◽  
Author(s):  
Jana Kazandjieva ◽  
Dimitrina Guleva ◽  
Assia Nikolova ◽  
Sonya Márina
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Maple Syrup Urine Disease ◽  
Skin Lesions ◽  
Branched Chain Amino Acids ◽  
Acrodermatitis Enteropathica ◽  
Metabolic Decompensation ◽  
Maple Syrup ◽  
Urine Disease ◽  
Branched Chain

Abstract Leucinosis (maple syrup urine disease - MSUD) is an inherited aminoacidopathy and organic aciduria caused by severe enzyme defect in the metabolic pathway of amino acids: leucine, isoleucine, and valine. The classical variant of the disease is characterized by accumulation of both amino and α-keto acids, particulary the most toxic rapid elevation of circulating leucine and its ketoacid, α-ketoisocaproate, which cause encephalopathy and life-threatening brain swelling. However, patients with the most severe form, classical maple syrup urine disease, may appear normal at birth, but develop acute metabolic decompensation within the first weeks of life with typical symptoms: poor feeding, vomiting, poor weight gain, somnolence and burnt sugar-smelling urine, reminiscent of maple syrup. Early diagnosis and dietary intervention improve the patient’s condition, prevent severe complications, and may allow normal intellectual development. We present a 4-month old infant with leucinosis dignosed 3 months earlier, due to elevated levels of amino acids: leucine, isoleucine and valine. The patient was full-term neonate with an uncomplecated delivery, without any family history of metabolic disorder or consanguinity. The infant was referred to a dermatologist, because of maculopapular exanthema on the scalp, trunk, upper and lower extremities, and exfoliative dermatitis of the perioral, particularly anogenital regions, associated with diarrhea. Skin involvement was associated with poor general condition of the infant exhibiting severe hypotension, anemic syndrome, dyspepsia and neurological symptoms. Exanthema developed a few days after the initiation of nutritional therapy for MSUD: isoleucine-, leucine-, and valine-free powdered medical food (MSUD-2) supplemented with iron. Zink levels were within normal ranges. Rapid skin improvement occurred after adequate branched-chain amino acids supplementation was commenced under regular laboratory control (normal zinc serum level with deficiencies of leucine and valine), skin hygiene with antiseptics, emollients and low potent topical corticosteroids. Treatment of acute metabolic decompensation and dietary restriction of branched-chain amino acids are the main aspects in the management of maple syrup urine disease. Common findings in patients with MSUD include: plasma amino acid imbalance, particularly of essential amino acids, failure to thrive attributed to restriction of particular precursor amino acids and natural proteins, micronutrient deficiencies or higher energy requirement due to chronic illness or inflammation. Due to low intake of branched-chain amino acids, some patients develop skin lesions known as acrodermatitis enteropathica-like syndrome. Here we report a case of an infant who developed acrodermatitis enteropathica-like skin eruptions due to branched-chain amino acid deficiency during treatment of maple syrup urine disease. According to available world literature, this is the first report of acrodermatitis enteropathica-like syndrome in an infant with maple syrup urine disease (leucinosis) in the Republic of Bulgaria.

scholarly journals Branched Chain Amino Acids Induce Apoptosis in Neural Cells without Mitochondrial Membrane Depolarization or Cytochromec Release: Implications for Neurological Impairment Associated with Maple Syrup Urine Disease

2000 ◽  
Vol 11 (5) ◽  
pp. 1919-1932 ◽  
Author(s):  
Philippe Jouvet ◽  
Pierre Rustin ◽  
Deanna L. Taylor ◽  
Jennifer M. Pocock ◽  
Ursula Felderhoff-Mueser ◽  
...  
Keyword(s):  
Amino Acids ◽  
Cytochrome C ◽  
Maple Syrup Urine Disease ◽  
Mitochondrial Membrane ◽  
Branched Chain Amino Acids ◽  
Keto Acid ◽  
Maple Syrup ◽  
Mitochondrial Membrane Depolarization ◽  
Urine Disease ◽  
Branched Chain

Maple syrup urine disease (MSUD) is an inborn error of metabolism caused by a deficiency in branched chain α-keto acid dehydrogenase that can result in neurodegenerative sequelae in human infants. In the present study, increased concentrations of MSUD metabolites, in particular α-keto isocaproic acid, specifically induced apoptosis in glial and neuronal cells in culture. Apoptosis was associated with a reduction in cell respiration but without impairment of respiratory chain function, without early changes in mitochondrial membrane potential and without cytochrome c release into the cytosol. Significantly, α-keto isocaproic acid also triggered neuronal apoptosis in vivo after intracerebral injection into the developing rat brain. These findings suggest that MSUD neurodegeneration may result, at least in part, from an accumulation of branched chain amino acids and their α-keto acid derivatives that trigger apoptosis through a cytochrome c-independent pathway.

Sign in / Sign up

Export Citation Format

Share Document