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.