Kapoor, R. R;
Flanagan, S. E;
Fulton, P.;
Chakrapani, A.;
Chadefaux, B.;
Ben-Omran, T.;
Banerjee, I.;
... Hussain, K.; + view all
(2009)
Hyperinsulinism-hyperammonaemia syndrome: novel mutations in the GLUD1 gene and genotype-phenotype correlations.
European Journal of Endocrinology
, 161
(5)
pp. 731-735.
10.1530/EJE-09-0615.
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Abstract
Background: Activating mutations in the GLUD1 gene (which encodes for the intra-mitochondrial enzyme glutamate dehydrogenase, GDH) cause the hyperinsulinism–hyperammonaemia (HI/HA) syndrome. Patients present with HA and leucine-sensitive hypoglycaemia. GDH is regulated by another intra-mitochondrial enzyme sirtuin 4 (SIRT4). Sirt4 knockout mice demonstrate activation of GDH with increased amino acid-stimulated insulin secretion. Objectives: To study the genotype–phenotype correlations in patients with GLUD1 mutations. To report the phenotype and functional analysis of a novel mutation (P436L) in the GLUD1 gene associated with the absence of HA. Patients and methods: Twenty patients with HI from 16 families had mutational analysis of the GLUD1 gene in view of HA (n=19) or leucine sensitivity (n=1). Patients negative for a GLUD1 mutation had sequence analysis of the SIRT4 gene. Functional analysis of the novel P436L GLUD1 mutation was performed. Results: Heterozygous missense mutations were detected in 15 patients with HI/HA, 2 of which are novel (N410D and D451V). In addition, a patient with a normal serum ammonia concentration (21 µmol/l) was heterozygous for a novel missense mutation P436L. Functional analysis of this mutation confirms that it is associated with a loss of GTP inhibition. Seizure disorder was common (43%) in our cohort of patients with a GLUD1 mutation. No mutations in the SIRT4 gene were identified. Conclusion: Patients with HI due to mutations in the GLUD1 gene may have normal serum ammonia concentrations. Hence, GLUD1 mutational analysis may be indicated in patients with leucine sensitivity; even in the absence of HA. A high frequency of epilepsy (43%) was observed in our patients with GLUD1 mutations.
| Type: | Article |
|---|---|
| Title: | Hyperinsulinism-hyperammonaemia syndrome: novel mutations in the GLUD1 gene and genotype-phenotype correlations |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1530/EJE-09-0615 |
| Publisher version: | http://dx.doi.org/10.1530/EJE-09-0615 |
| Language: | English |
| Additional information: | © 2009 European Society of Endocrinology. This is an Open Access article distributed under the terms of the European Journal of Endocrinology's Re-use Licence which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. For information see http://www.eje-online.org/misc/reuse_licence.dtl |
| UCL classification: | UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Population Health Sciences > UCL GOS Institute of Child Health |
| URI: | https://discovery-pp.ucl.ac.uk/id/eprint/20123 |
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