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Classical homocystinuria

Warren D Kruger
Cystathionine β-synthase (CBS) deficiency (Online Mendelian Inheritance in Man [OMIM] 236,200) is an autosomal recessive disorder that is caused by mutations in the CBS gene. It is the most common inborn error of sulfur metabolism and is the cause of classical homocystinuria, a condition characterized by very high levels of plasma total homocysteine and methionine. Although recognized as an inborn error of metabolism over 60years ago, these is still much we do not understand related to how this specific metabolic defect gives rise to its distinct phenotypes...
July 2017: Molecular Genetics and Metabolism
Sapna Gupta, Liqun Wang, Warren D Kruger
Mutations in the cystathionine beta-synthase (CBS) gene are the cause of classical homocystinuria, the most common inborn error in sulfur metabolism. The c.797 G>A (p.R266K) mutation in CBS was originally described in several Norwegian pyridoxine responsive CBS deficient patients, and heterologous gene expression studies have shown that the protein has near wild-type levels of enzyme activity. Here, we characterize a transgenic mouse lacking endogenous Cbs and expressing p.R266K human CBS protein from a zinc inducible metallothionein promoter (Tg-R266K Cbs(-/-) )...
July 2017: Human Mutation
Arushi Gahlot Saini, Hansashree Padmanabha, Savita Attri, Pratibha Singhi
No abstract text is available yet for this article.
May 3, 2017: BMJ Case Reports
Tomas Majtan, Insun Park, Richard S Carrillo, Erez M Bublil, Jan P Kraus
Homocystinuria due to loss of cystathionine beta-synthase (CBS) causes accumulation of homocysteine and depletion of cysteine. Current treatments are suboptimal, and thus the development of an enzyme replacement therapy based on PEGylated human truncated CBS (PEG-CBS) has been initiated. Attenuation of potency was observed, which necessitated a screen of several PEG-CBS conjugates for their efficacy to correct and maintain the plasma metabolite profile of murine homocystinuria after repeated administrations interrupted with washouts...
May 1, 2017: Biomacromolecules
João B Vicente, Henrique G Colaço, Francesca Malagrinò, Paulo E Santo, André Gutierres, Tiago M Bandeiras, Paula Leandro, José A Brito, Alessandro Giuffrè
The human disease classical homocystinuria results from mutations in the gene encoding the pyridoxal 5'-phosphate- (PLP-) dependent cystathionine β-synthase (CBS), a key enzyme in the transsulfuration pathway that controls homocysteine levels, and is a major source of the signaling molecule hydrogen sulfide (H2S). CBS activity, contributing to cellular redox homeostasis, is positively regulated by S-adenosyl-L-methionine (AdoMet) but fully inhibited upon CO or NO• binding to a noncatalytic heme moiety. Despite extensive studies, the molecular basis of several pathogenic CBS mutations is not yet fully understood...
2017: Oxidative Medicine and Cellular Longevity
René L Jacobs, Hua Jiang, John P Kennelly, David J Orlicky, Robert H Allen, Sally P Stabler, Kenneth N Maclean
Classical homocystinuria (HCU) due to inactivating mutation of cystathionine β-synthase (CBS) is a poorly understood life-threatening inborn error of sulfur metabolism. A previously described cbs-/- mouse model exhibits a semi-lethal phenotype due to neonatal liver failure. The transgenic HO mouse model of HCU exhibits only mild liver injury and recapitulates multiple aspects of the disease as it occurs in humans. Disruption of the methionine cycle in HCU has the potential to impact multiple aspect of phospholipid (PL) metabolism by disruption of both the Kennedy pathway and phosphatidylethanolamine N-methyltransferase (PEMT) mediated synthesis of phosphatidylcholine (PC)...
March 2, 2017: Molecular Genetics and Metabolism
Emily Woods, Charlotte Dawson, Latha Senthil, Tarekegn Geberhiwot
A 30-year-old woman presented with severe headache, dysarthria and right hemiparesis. She was treated for suspected viral encephalopathy and recovered over the following weeks although the headaches persisted. Two months later she was treated in-hospital for pulmonary embolism. The following year she was readmitted for increased frequency of headaches and was given a diagnosis of migraine. A subsequent MRI head scan was suggestive of longstanding venous sinus infarcts and neuroradiology review concluded that encephalitis had been the incorrect initial diagnosis...
January 30, 2017: BMJ Case Reports
Gwendolyn Gramer, Ghassan Abdoh, Tawfeg Ben-Omran, Noora Shahbeck, Rehab Ali, Laila Mahmoud, Junmin Fang-Hoffmann, Georg F Hoffmann, Hilal Al Rifai, Jürgen G Okun
BACKGROUND: Newborn screening is a precondition for early diagnosis and succeßsful treatment of remethylation disorders and classical homocystinuria (cystathionine-β-synthase deficiency). Newborn screening for classical homocystinuria using total homocysteine measurement in dried blood spots has been very successfully performed for many years for newborns from Qatar. METHODS: A new optimized newborn screening strategy for remethylation disorders and homocystinuria was developed and evaluated for newborns from Qatar using total homocysteine measurement as first-tier and methionine, methionine-phenylalanine-ratio and propionylcarnitine as second-tiers...
January 19, 2017: World Journal of Pediatrics: WJP
Miguel Oliveira Santos, Ruth Geraldes, Isabel Conceição
Classic homocystinuria is one of the most common causes of hereditary hyperhomocysteinemia. It is an autosomal recessive and multisystemic disorder due to cystathionine β-synthase deficiency. We described a case of an 18-year-old Portuguese man with an ischaemic stroke, who was subsequently diagnosed with classic homocystinuria [Thr191Met (c.572C>T) CBS mutation] associated with a sensorimotor neuropathy. The patient had a good clinical and metabolic response to pyridoxine plus methionine-restricted diet after 12 months of treatment...
2016: BMJ Case Reports
Jürgen G Okun, Hongying Gan-Schreier, Tawfeq Ben-Omran, Kathrin V Schmidt, Junmin Fang-Hoffmann, Gwendolyn Gramer, Ghassan Abdoh, Noora Shahbeck, Hilal Al Rifai, Abdul Latif Al Khal, Gisela Haege, Chuan-Chi Chiang, David C Kasper, Bridget Wilcken, Peter Burgard, Georg F Hoffmann
BACKGROUND: In classical homocystinuria (HCU, MIM# 236200) due to the deficiency of cystathionine β-synthase (EC there is a clear evidence for the success of early treatment. The aim of this study was to develop and evaluate a two-tier strategy for HCU newborn screening. METHODS: We reevaluated data from our newborn screening programme for Qatar in a total number of 125,047 neonates including 30 confirmed HCU patients. Our hitherto existing screening strategy includes homocysteine (Hcy) measurements in every child, resulting in a unique dataset for evaluation of two-tier strategies...
2017: JIMD Reports
Dwight D Koeberl
Inherited metabolic disorders are often characterized by the lack of an essential enzyme and are currently treated by dietary restriction and other strategies to replace the substrates or products of the missing enzyme. Patients with homocystinuria lack the enzyme cystathionine β-synthase (CBS), and many of these individuals do not respond to current treatment protocols. In this issue of the JCI, Bublil and colleagues demonstrate that enzyme replacement therapy (ERT) provides long-term amelioration of homocystinuria-associated phenotypes in CBS-deficient murine models...
June 1, 2016: Journal of Clinical Investigation
Tomas Majtan, Angel L Pey, June Ereño-Orbea, Luis Alfonso Martínez-Cruz, Jan P Kraus
Classical homocystinuria (HCU) is the most common loss-of-function inborn error of sulfur amino acids metabolism. HCU is caused by a deficiency in enzymatic degradation of homocysteine, a toxic intermediate of methionine transformation to cysteine, chiefly due to missense mutations in the cystathionine betasynthase (CBS) gene. As with many other inherited disorders, the pathogenic mutations do not target key catalytic residues, but rather introduce structural perturbations leading to an enhanced tendency of the mutant CBS to misfold and either to form non-functional aggregates or to undergo proteasome-dependent degradation...
2016: Current Drug Targets
Viktor Kožich, Jakub Krijt, Jitka Sokolová, Petra Melenovská, Pavel Ješina, Roman Vozdek, Tomáš Majtán, Jan P Kraus
Two enzymes in the transsulfuration pathway of homocysteine -cystathionine beta-synthase (CBS) and gamma-cystathionase (CTH)-use cysteine and/or homocysteine to produce the important signaling molecule hydrogen sulfide (H2S) and simultaneously the thioethers lanthionine, cystathionine or homolanthionine. In this study we explored whether impaired flux of substrates for H2S synthesis and/or deficient enzyme activities alter production of hydrogen sulfide in patients with homocystinurias. As an indirect measure of H2S synthesis we determined by LC-MS/MS concentrations of thioethers in plasma samples from 33 patients with different types of homocystinurias, in 8 patient derived fibroblast cell lines, and as reaction products of seven purified mutant CBS enzymes...
July 2016: Biochimie
Hideo Sasai, Nobuyuki Shimozawa, Takahiko Asano, Norio Kawamoto, Takahiro Yamamoto, Takeshi Kimura, Minako Kawamoto, Eiko Matsui, Toshiyuki Fukao
Cystathionine β-synthase (CBS) deficiency, well known as classical homocystinuria, is a rare autosomal recessive inborn error of homocysteine and sulfur metabolism. CBS converts homocysteine to cystathionine. The clinical features of untreated CBS deficiency include myopia, ectopia lentis, mental retardation, skeletal anomalies resembling Marfan syndrome, and thromboembolic events. Cerebral white matter lesions (CWMLs), identified in magnetic resonance imaging (MRI), are related to various clinical conditions including ischemia, inflammation, demyelination, infection, a tumor, and metabolic disorders such as phenylketonuria...
2015: Tohoku Journal of Experimental Medicine
Ertugrul Kiykim, Cigdem Aktuglu Zeybek, Tanyel Zubarioglu, Serif Cansever, Cengiz Yalcinkaya, Erdogan Soyucen, Ahmet Aydin
Autism spectrum disorders (ASDs) are a major health problem because of their high prevalence in the general population. The pathophysiology of ASD remains unclear, although genetic defects may be detected in 10-20% of affected patients. Among these cases, the prevalence of inherited metabolic disorders (IMD) has not been extensively evaluated. IMDs responsible for ASDs are usually identified via clinical manifestations such as microcephaly, dysmorphic features, convulsions, and hepatosplenomegaly. Infrequently, patients with no additional clinical symptoms suggestive of an IMD may be diagnosed as having an idiopathic ASD...
February 2016: Autism Research: Official Journal of the International Society for Autism Research
Catherine Lynn T Silao, Terence Diane F Fabella, Kahlil Izza D Rama, Sylvia C Estrada
BACKGROUND: Classic homocystinuria due to cystathionine β-synthase (CBS) deficiency is an autosomal recessive disorder of sulfur metabolism. Clinical manifestations include mental retardation, dislocation of the optic lens (ectopia lentis), skeletal abnormalities and a tendency to thromboembolic episodes. We present the first mutational analysis of CBS in a Filipino patient with classic homocystinuria. METHODS: Genomic DNA was extracted from peripheral blood collected from a diagnosed Filipino patient with classic homocystinuria...
October 2015: Pediatrics International: Official Journal of the Japan Pediatric Society
Haitham El Bashir, Lubna Dekair, Yasmeen Mahmoud, Tawfeg Ben-Omran
BACKGROUND: Classical homocystinuria due to cystathionine β-synthase (CBS) deficiency (OMIM 236200) is a recessively inherited condition caused by mutations in the CBS gene. The founder mutation p.R336C accounts for almost all CBS deficiency in Qatar, affecting approximately 1 in 1,800 births, making it the most prevalent monogenic disease among the Qatari population. Untreated patients can have severe intellectual disability (ID), devastating multisystem complications and premature death...
2015: JIMD Reports
Ana Marcão, María L Couce, Célia Nogueira, Helena Fonseca, Filipa Ferreira, José M Fraga, M Dolores Bóveda, Laura Vilarinho
Homocystinuria due to cystathionine β-synthase deficiency or "classical homocystinuria" is a rare autosomal recessive condition resulting in altered sulfur metabolism with elevated methionine and homocysteine in plasma and homocystine in urine. This condition is characterized by a high clinical heterogeneity, which contributes to late clinical diagnosis, usually only made after irreversible damage has occurred. Treatment is effective if started before clinical symptoms. The analysis of methionine levels by tandem mass spectrometry (MS/MS) allows the newborn screening for homocystinuria, but false-positive results can be frequently obtained and lead to the unwanted identification of methionine adenosyl transferase (MAT I/III) deficiency...
2015: JIMD Reports
Yung-Hsiu Lu, Li-Mei Cheng, Yu-Hsiu Huang, Ming-Yu Lo, Tina Jui-Ting Wu, Hsiang-Yu Lin, Ting-Rong Hsu, Dau-Ming Niu
BACKGROUND & AIMS: Many studies have reported that serum total homocysteine (tHcy) levels in cystathionine-beta-synthase (CBS) carriers are usually normal and only elevated after a methionine load. However, the amount of methionine required for a loading test is non-physiological and is never reached with regular feeding. Therefore, CBS carriers do not seem to be at an increased risk of cardiovascular diseases. However, the risk of cardiovascular diseases of CBS carriers with folate deficiency has not been studied...
December 2015: Clinical Nutrition: Official Journal of the European Society of Parenteral and Enteral Nutrition
Petra Melenovská, Jana Kopecká, Jakub Krijt, Aleš Hnízda, Kateřina Raková, Miroslav Janošík, Bridget Wilcken, Viktor Kožich
Classical homocystinuria is caused by mutations in the cystathionine β-synthase (CBS) gene. Previous experiments in bacterial and yeast cells showed that many mutant CBS enzymes misfold and that chemical chaperones enable proper folding of a number of mutations. In the present study, we tested the extent of misfolding of 27 CBS mutations previously tested in E. coli under the more folding-permissive conditions of mammalian CHO-K1 cells and the ability of chaperones to rescue the conformation of these mutations...
March 2015: Journal of Inherited Metabolic Disease
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