Hypomethylation of Monoamine Oxidase A promoter/exon 1 region is associated with temper outbursts in Prader-Willi syndrome

Abstract

AbstractBackgroundPrader-Willi syndrome (PWS) is a rare neurodevelopmental disorder caused by the absence of paternally expressed and maternally imprinted genes on chromosome 15q 11.2-13. It is associated with a certain behavioural phenotype with repetitive and ritualistic behaviours, skin-picking and temper outbursts. Temper outbursts are characterized by verbal and physical aggression with screaming, destroying property, and/or physical aggression towards others. They drastically effect the quality of life of the individuals as well as the relatives and caregivers. Recent studies show a promising therapeutic effect of serotonin reuptake inhibitors like sertraline on frequency and intensity of outbursts. Monoamine oxidase A (MAOA) (X p11.23) plays a crucial role in the metabolism of monoamines such as serotonin, norepinephrine, and dopamine. Dysregulation in methylation of the CpG island spanning the promoter region and exon 1 of MAOA is implicated in impulsive and aggressive behaviour.MethodsIn the present study, methylation rates of CpG dinucleotides in the MAOA promoter and exon 1 region were determined from DNA derived from whole blood samples of PWS patients (n=32) and controls (n=14) matched for age, sex and BMI via bisulfite sequencing. PWS patients were grouped into those showing temper outbursts, and those who do not.ResultsOverall, PWS patients show a significant lower methylation rate at the promoter/exon 1 region than healthy controls in both sexes. Furthermore, PWS patients, male as well female with temper outbursts show a significant lower methylation rate than those without temper outbursts (p<0.001 and p=0.006)ConclusionThe MAOA promoter/exon 1 region methylation seems to be dysregulated in PWS patients in sense of a hypomethylation, especially in those suffering from temper outbursts. As MAOA is involved in the metabolism of serotonin, we conclude that this dysregulation plays a crucial role in the pathophysiology of temper outbursts in PWS. Furthermore, our findings suggest, that dysregulation of certain genes outside the PWS locus contribute to the behavioural phenotype of PWS.