| A rare genetic neurodevelopmental disorder with primordial microcephaly, with characteristics of primary microcephaly, moderate to severe intellectual disability and global developmental delay. Variable brain malformations are common ranging from simplified gyration, to cortical malformations such as pachygyria, polymicrogyria, reduced sulcation and midline defects. Craniofacial dysmorphism (e.g. sloping forehead, high and broad nasal bridge) are related to the primary microcephaly. Short stature is frequently observed, and may be severe. Germline biallelic variants in RTTN (18q22.2) are responsible for the disease. The pattern of inheritance is autosomal recessive. |
