The behavioral phenotype of neurogenetic disorders associated with intellectual disability often includes psychiatric comorbidity. The objectives of this systematic review and meta-analysis were to systematically review the prevalence of psychiatric disorders and symptoms in children and adolescents with these disorders and compare phenotypic signatures between syndromes.MEDLINE and PsycINFO databases were searched for articles from inception to December 2018. Eligible articles were peer reviewed, published in English and reported prevalence data for psychiatric disorders and symptoms in children aged four to 21 years, using a formal psychiatric assessment or a standardized assessment of mental health symptomology. Pooled prevalence was determined using a random effects meta-analysis in studies with sufficient data. Prevalence estimates were compared with general population data using a test of binomial proportions.Of 2301 studies identified for review, 39 papers were included in the final pool which provided data on 4039 individuals. Ten syndromes were represented and five were predominant: Down syndrome, 22q11.2 deletion syndrome, Fragile X syndrome, Williams syndrome and Prader-Willi syndrome. The Child Behavior Checklist was the most commonly used assessment tool for psychiatric symptoms. The pooled prevalence with total scores above the clinical threshold was lowest for Down syndrome (32%; 95% CI, 19%-44%) and highest for Prader-Willi syndrome (74%; 95% CI, 65%-82%) with each syndrome associated with significantly higher prevalence than in the general population. Parallel trends were observed for the internalizing and externalizing domains and social subscale scores.Differential vulnerability for 'psychiatric phenotype' expression across the disorders was observed. Syndromes with higher levels of social ability or competence appear to offer relative protection against developing psychopathology, and this preliminary finding merits further exploration.