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Ornithine transcarbamylase deficiency combined with type 1 diabetes mellitus - a challenge in clinical and dietary management

  • Ornithine transcarbamylase (OTC) deficiency is the most common urea cycle defect. The clinical presentation in female manifesting carriers varies both in onset and severity. We report on a female with insulin dependent diabetes mellitus and recurrent episodes of hyperammonemia. Since OTC activity measured in a liver biopsy sample was within normal limits, OTC deficiency was initially excluded from the differential diagnoses of hyperammonemia. Due to moderately elevated homocitrulline excretion, hyperornithinemia-hyperammonemia-homocitrullinuria-syndrome was suggested, but further assays in fibroblasts showed normal ornithine utilization. Later, when mutation analysis of the OTC gene became available, a known pathogenic missense mutation (c.533C>T) in exon 5 leading to an exchange of threonine-178 by methionine (p.Thr178Met) was detected. Skewed X-inactivation was demonstrated in leukocyte DNA. In the further clinical course the girl developed marked obesity. By initiating physical activities twice a week, therapeutic control of both diabetes and OTC deficiency improved, but obesity persisted. In conclusion, our case confirms that normal hepatic OTC enzyme activity measured in a single liver biopsy sample does not exclude a clinical relevant mosaic of OTC deficiency because of skewed X-inactivation. Mutation analysis of the OTC gene in whole blood may be a simple way to establish the diagnosis of OTC deficiency. The joint occurrence of OTC deficiency and diabetes in a patient has not been reported before.

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Document Type:Article
Author:Sarah C. Grünert, Pablo Villavicencio-Lorini, Bendicht Wermuth, Willy Lehnert, Jörn Oliver Sass, K. Otfried Schwab
Parent Title (English):Journal of Diabetes & Metabolic Disorders
First Page:37
Publisher:BioMed Central
Date of first publication:2013/07/05
© 2013 Grünert et al. This is an Open Access article distributed under the terms of the Creative Commons Attribution License.
Departments, institutes and facilities:Institut für funktionale Gen-Analytik (IFGA)
Dewey Decimal Classification (DDC):6 Technik, Medizin, angewandte Wissenschaften / 61 Medizin und Gesundheit / 610 Medizin und Gesundheit
Entry in this database:2018/08/18
Licence (German):License LogoCreative Commons - CC BY - Namensnennung 3.0