The main objective is to constitute a precise and exhaustive collection of clinical data (somatic and neurobehavioral data) of individuals affected by various frequent monogenic forms of neurodevelopmental disorders to better characterize the clinical phenotype of these disorders.

A better knowledge of these manifestations is necessary to improve the management of individuals with these disorders.

The secondary objectives of this research are to inform practitioners, patients and their families about the clinical characteristics of these disorders to better understand their diversity and, finally, to improve their screening and diagnosis. Thus, our study aims at establishing clinical scores, linking genotypes and phenotypes and producing documents for professionals (such as the PNDS (National Diagnostic and Care Protocols))

Inclusion criteria:

• Minor patient whose age is ≥ 4 years and ≤18 years
• Major patient with intellectual disability
• Patient treated in a participating center for TND linked to a mutation in one of the genes frequently mutated in this pathology, such as the DYRK1A, KMT2A or other genes;
• Patient having previously been seen in genetic consultation
• Parent (or legal guardian) not having expressed, after information, his opposition to the reuse of his data for the purposes of this research.

Exclusion criteria:

- Parent (or legal guardian) who expressed his opposition to participating in the study.

Patient treated for TND linked to a mutation in one of the genes frequently mutated in this pathology, such as the DYRK1A, KMT2A or other genes