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Clin Genet. 2016 Jan;89(1):120-7. doi: 10.1111/cge.12589. Epub 2015 Apr 19.

New insights into Brunner syndrome and potential for targeted therapy.

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Department of Clinical Genetics, GOLD (Genetics of Learning Disability) service, Waratah, New South Wales, Australia.
University of New South Wales, Waratah, New South Wales, Australia.
School of Paediatrics and Reproductive Health and Robinson Institute, The University of Adelaide, Adelaide, South Australia, Australia.
Department of Paediatrics and Child Health, University of Sydney, Sydney, New South Wales, Australia.
Department of Biochemistry, The Children's Hospital at Westmead, Sydney, New South Wales, Australia.
Department of Endocrinology, Nepean Hospital, Sydney, New South Wales, Australia.
Department of Human Molecular Genetics.
Department of Computational Molecular Biology, Max Planck Institute for Molecular Genetics, Berlin, Germany.


We report two families with Brunner syndrome living in one state of Australia. The first family had a predicted protein-truncating variant of monoamine oxidase A (MAOA) (p.S251KfsX2). Affected males had mild intellectual disability (ID), obsessive behaviour, limited friendships and were introverted and placid during clinical interview. The family disclosed episodic explosive aggression after a diagnosis was made. The second family had a missense variant in MAOA (p.R45W). Affected males had borderline-mild ID, attention deficit disorder and limited friendships. One had a history of explosive aggression in childhood and episodic symptoms of flushing, headaches and diarrhoea. Their carrier mother had normal intelligence but similar episodic symptoms. Characteristic biochemical abnormalities included high serum serotonin and urinary metanephrines and low urinary 5-hydroxyindoleacetic acid (5-HIAA) and vanillylmandelic acid (VMA). Symptomatic individuals in the second family had particularly high serotonin levels, and treatment with a serotonin reuptake inhibitor and dietary modification resulted in reversal of biochemical abnormalities, reduction of 'serotonergic' symptoms and behavioural improvement. Brunner syndrome should be considered as a cause of mild ID with paroxysmal behavioural symptoms. It can be screened for with serum/urine metanephrine and serotonin measurement. Cautious treatment with a serotonin reuptake inhibitor, dietary modifications and avoidance of medications contraindicated in patients on monoamine oxidase inhibitors can improve symptoms.


Brunner syndrome; MAO-A deficiency; autism spectrum disorder; diagnosis; intellectual disability; serotonin; treatment

[Indexed for MEDLINE]

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