Open Access Research article

Mutation screening of ASMT, the last enzyme of the melatonin pathway, in a large sample of patients with Intellectual Disability

Cecile Pagan123, Hany Goubran Botros12, Karine Poirier34, Anne Dumaine5, Stéphane Jamain56, Sarah Moreno12, Arjan de Brouwer7, Hilde Van Esch8, Richard Delorme12, Jean-Marie Launay39, Andreas Tzschach10, Vera Kalscheuer10, Didier Lacombe11, Sylvain Briault1213, Frédéric Laumonnier141516, Martine Raynaud14151617, Bregje W van Bon7, Marjolein H Willemsen7, Marion Leboyer181956, Jamel Chelly34 and Thomas Bourgeron1220*

Author Affiliations

1 Human Genetics and Cognitive Functions, Institut Pasteur, Paris, France

2 CNRS URA 2182 "Genes, synapses et cognition", Institut Pasteur, Paris, France

3 University Paris Descartes, Paris, France

4 Institut Cochin, CNRS ULD 8104, Paris, France

5 Inserm U 955, IMRB, Psychiatry Genetics, Creteil, F-94000, France

6 Foundation Fondamental, Creteil, France

7 Department of Human Genetics, Nijmegen Centre for Molecular Life Sciences, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands

8 Center for Human Genetics, University Hospitals Leuven, B-3000 Leuven, Belgium

9 Service de Biochimie, INSERM U942, Hopital Lariboisière, Assistance Publique-Hopitaux de Paris, Paris, France

10 Max Planck Institute for Molecular Genetics, Department Ropers, Berlin, Germany

11 Service de Génétique Médicale, Hôpital Pellegrin, CHU de Bordeaux, Bordeaux, France

12 UMR 6218, CNRS, IEM, équipe « génétique expérimentale et moléculaire », université d'Orléans, Orléans, France

13 Centre hospitalier régional d'Orléans, Orléans, France

14 Inserm U930 "Imaging and Brain", Tours, France

15 University François-Rabelais, Tours, France

16 CNRS ERL3106, Tours France

17 Centre Hospitalier Régional Universitaire, Service de Génétique, Tours, France

18 University Paris-East, Faculty of Medicine, UMR-S 955, Creteil, F-94000, France

19 AP-HP, Henri Mondor-Albert Chenevier Group, Department of Psychiatry, Creteil, F-94000, France

20 University Denis Diderot Paris 7, Paris, France

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BMC Medical Genetics 2011, 12:17  doi:10.1186/1471-2350-12-17

Published: 20 January 2011

Abstract

Background

Intellectual disability (ID) is frequently associated with sleep disorders. Treatment with melatonin demonstrated efficacy, suggesting that, at least in a subgroup of patients, the endogenous melatonin level may not be sufficient to adequately set the sleep-wake cycles. Mutations in ASMT gene, coding the last enzyme of the melatonin pathway have been reported as a risk factor for autism spectrum disorders (ASD), which are often comorbid with ID. Thus the aim of the study was to ascertain the genetic variability of ASMT in a large cohort of patients with ID and controls.

Methods

Here, we sequenced all exons of ASMT in a sample of 361 patients with ID and 440 controls. We then measured the ASMT activity in B lymphoblastoid cell lines (BLCL) of patients with ID carrying an ASMT variant and compared it to controls.

Results

We could identify eleven variations modifying the protein sequence of ASMT (ID only: N13H, N17K, V171M, E288D; controls only: E61Q, D210G, K219R, P243L, C273S, R291Q; ID and controls: L298F) and two deleterious splice site mutations (IVS5+2T>C and IVS7+1G>T) only observed in patients with ID. We then ascertained ASMT activity in B lymphoblastoid cell lines from patients carrying the mutations and showed significantly lower enzyme activity in patients carrying mutations compared to controls (p = 0.004).

Conclusions

We could identify patients with deleterious ASMT mutations as well as decreased ASMT activity. However, this study does not support ASMT as a causative gene for ID since we observed no significant enrichment in the frequency of ASMT variants in ID compared to controls. Nevertheless, given the impact of sleep difficulties in patients with ID, melatonin supplementation might be of great benefit for a subgroup of patients with low melatonin synthesis.