Background: mental disorders in children, accompanied by a whole range of disorders, are not uncommon in the clinical practice of a child psychiatrist. The aim was to describe the clinical features of mental disorders in early and preschool age that occur against the background of connective tissue diathesis, using a specific clinical example. Patients and methods: clinical observations of children at risk for the development of mental pathology, including autism spectrum disorders, anxiety-depressive disorders, hyperactivity syndrome. Results: the article presents a brief review of literature data on certain differentiated syndromes of connective tissue dysplasia (CTD), in the clinical symptoms in addition to phenotypic signs and minor developmental anomalies, there are mental disorders. A clinical illustration of the combination of CTD syndrome and clinical manifestations of psychopathological disorders in a 5-year-old girl with development of the type of “schizotypal diathesis”, having various connective tissue anomalies, is given. Conclusion: the study of connective tissue diathesis in the structure of premorbid risk factors for mental diseases, including endogenous diseases, will clarify the nature of these conditions, expand our understanding of possible ways of prevention and therapy.