| Definition: |
A chromosomal deletion syndrome that has_material_basis_in a deletion, translocation, ring chromosome formation or other structural change of the terminal end of chromosome 22 in the 22q13 region or a disease-causing mutation of the SHANK3 gene and that is characterized by neonatal hypotonia, absent to severely delayed speech, global developmental delay, and minor dysmorphic facial features. Most cases of 22q13.3 deletion syndrome are not inherited with 20% of cases (autosomal dominant) inherited from a parent. The deletion occurs most often as a random event during the formation of reproductive cells (eggs or sperm) or in early fetal development. |