New Krebs cycle defect

• October 6th, 2008

Nat Genet. 2008 Oct;40(10):1230-4. Epub 2008 Sep 21.

Insights from retinitis pigmentosa into the roles of isocitrate dehydrogenases in the Krebs cycle.

Hartong DT, Dange M, McGee TL, Berson EL, Dryja TP, Colman RF.

We still have things to learn about the Krebs cycle….
Indeed, by studying families with Retinitis Pigmentosa, Hartong and colleagues identified individuals with functional defects in NAD-specific isocitrate dehydrogenase.
What is surprinsing is that these individuals do not have a generalized mitochondrial syndrome with encephalopathy (seen in homozygotes with defects of other enzymes of the krebs cycle) but the only affected organ is the retina. It is believed that elsewhere in the body, NADP-specific isocitrate dehydrogenase catalyzes the oxidation of isocitrate to alpha-ketoglutarate.

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Philippe Campeau, MD
Resident in Medical Genetics at McGill University
OMMBID Blog Administrator

ICIEM next meeting

• September 6th, 2008

11th International Congress of Inborn Errors of Metabolism (ICIEM), San Diego, California, USA. August 29 - Sept 2, 2009
Check out: http://www.iciem2009.org

UCD cross-sectional study in the US

• July 15th, 2008

This study performed by 8 US sites included 183 patients. The data was obtained by interviews, physical examinations, neuropsychological testing and laboratory analyses. OTC deficiency was the most frequent condition. 39% of all patients had intellectual and developmental disabilities.

For more details on this very useful cross-sectional study, please refer to:

Mol Genet Metab. 2008 Aug;94(4):397-402. Epub 2008 Jun 17.

Cross-sectional multicenter study of patients with urea cycle disorders in the United States.

Tuchman M, Lee B, Lichter-Konecki U, Summar ML, Yudkoff M, Cederbaum SD, Kerr DS,
Diaz GA, Seashore MR, Lee HS, McCarter RJ, Krischer JP, Batshaw ML; Urea Cycle
Disorders Consortium of the Rare Diseases Clinical Research Network.

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Click this link to see the most recent online abstracts of major genetics journals.
Philippe Campeau, MD
Resident in Medical Genetics at McGill University
OMMBID Blog Administrator

Mefolinate (5-methyltetrahydrofolate) as a treatment of severe MTHFR deficiency

• June 29th, 2008

Li, D. et al. Mefolinate (5-methyltetrahydrofolate), but not folic acid, decreases mortality in an animal model of severe methylenetetrahydrofolate reductase deficiency. Journal of Inherited Metabolic Disease Volume 31, Number 3 / June, 2008
In a mouse model of severe MTHFR deficiency, Mefolinate administration to the mother improved survival and cerebellar morphology in the pups. This agent could potentially be used eventually in clinical trials for the rare patients with severe MTHFR deficiency.
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Click this link to see the most recent online abstracts of major genetics journals.

Philippe Campeau, MD
Resident in Medical Genetics at McGill University
OMMBID Blog Administrator

MMBID 8e Archive Chapter 191 - Cystinuria

• June 26th, 2008

Download a PDF of the seminal chapter from MMBID 8e.

Click here to access the most up-to-date version of Chapter 191 on OMMBID.

Transaldolase deficiency

• May 21st, 2008

Mol Genet Metab. 2008 Jun;94(2):255-8. Epub 2008 Mar 10.

Transaldolase deficiency in a two-year-old boy with cirrhosis.

Wamelink MM, Struys EA, Salomons GS, Fowler D, Jakobs C, Clayton PT.

In this brief communication, the authors describe a new patient with transaldolase deficiency, with hematological, renal and hepatic manifestations. They also review previously reported cases of this recently described condition.

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Click this link to see the most recent online abstracts of major genetics journals.
Philippe Campeau, MD
Resident in Medical Genetics at McGill University
OMMBID Blog Administrator

Involvement of Bardet-Biedl proteins in neural crest cell migration

• May 6th, 2008

Proc Natl Acad Sci U S A. 2008 Apr 28 [Epub ahead of print]

Inhibition of neural crest migration underlies craniofacial dysmorphology and Hirschsprung’s disease in Bardet-Biedl syndrome.

Tobin JL, Di Franco M, Eichers E, May-Simera H, Garcia M, Yan J, Quinlan R, Justice MJ, Hennekam RC, Briscoe J, Tada M, Mayor R, Burns AJ, Lupski JR, Hammond P, Beales PL.

In this publication, the authors combine data from facial dysmorphology modeling, with experiments in mice and zebrafish to demonstrate their hypothesis that the proteins mutated in Bardet-Biedl syndrome are involved in neural crest cell migration.

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Click this link to see the most recent online abstracts of major genetics journals.

Philippe Campeau, MD
Resident in Medical Genetics at McGill University
OMMBID Blog Administrator

Another gene involved in ubiquinone deficiency

• April 10th, 2008

Am J Hum Genet. 2008 Mar;82(3):623-30.

CABC1 gene mutations cause ubiquinone deficiency with cerebellar ataxia and
seizures.

Mollet J, Delahodde A, Serre V, Chretien D, Schlemmer D, Lombes A, Boddaert N,
Desguerre I, de Lonlay P, de Baulny HO, Munnich A, Rötig A.

Investigators rom Paris have studied patients with CoQ10 deficiency from three families (presenting mostly with myopathy and ataxia), and systematically sequenced genes in the ubiquinone biosynthesis pathway. Mutations were found in CABC1, and the mutations were proven to be pathogenic in a yeast model. The role of the protein encoded by this gene is not precisely known yet.

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Click this link to see the most recent online abstracts of major genetics journals.
Philippe Campeau, MD
Resident in Medical Genetics at McGill University
OMMBID Blog Administrator

SSIEM 2008 meeting

• April 3rd, 2008

Registration for the September 2008 SSIEM meeting in Lisboa Portugal, is now open.

http://www.ssiem2008.com

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Click this link to see the most recent online abstracts of major genetics journals.

Philippe Campeau, MD
Resident in Medical Genetics at McGill University
OMMBID Blog Administrator

Metabolomics for IEMs

• March 24th, 2008

Clin Chem. 2007 Dec;53(12):2169-76. Epub 2007 Oct 19.
Metabolomics identifies perturbations in human disorders of propionate metabolism.
Wikoff WR, Gangoiti JA, Barshop BA, Siuzdak G.
In this publications, the authors use mass-based metabolomics to identify compounds which differ from normal individuals in the plasma of patients with methylmalonic aciduria and propionic aciduria.
Not surprinsingly, propionylcarnitine was the best marker for the disease. New compounds such as gamma-butyrobetaine (possibly related to carnitine supplementation) and other unidentified compounds were detected.

This demonstrates the potential usefulness of metabolomics in inborn errors of metabolism, to identify new markers of the disease (e.g. to follow treatment). Eventually, if the process is optimized to allow rapid screening of samples, it might become possible to identify new IEMs using such metabolomic approaches.

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Click this link to see the most recent online abstracts of major genetics journals.
Philippe Campeau, MD
Resident in Medical Genetics at McGill University
OMMBID Blog Administrator