- Microcephaly (HP:0000252): Head circumference below 2 standard deviations below the mean for age and gender. Evidence: PCS. (PMID:10973257)
- Sloping forehead (HP:0000340): Inclination of the anterior surface of the forehead from the vertical more than two standard deviations above the mean (objective); or apparently excessive posterior sloping of the forehead in a lateral view. Evidence: PCS. (PMID:10973257)
- Cerebellar hypoplasia (HP:0001321): Cerebellar hypoplasia is a descriptive term implying a cerebellum with a reduced volume, but a normal shape and is stable over time. Evidence: PCS. (PMID:10973257)
- Generalized-onset seizure (HP:0002197): A generalized-onset seizure is a type of seizure originating at some point within, and rapidly engaging, bilaterally distributed networks. The networks may include cortical and subcortical structures but not necessarily the entire cortex. Evidence: PCS. (PMID:10973257)
- Hypotonia (HP:0001252): Hypotonia is an abnormally low muscle tone (the amount of tension or resistance to movement in a muscle). Even when relaxed, muscles have a continuous and passive partial contraction which provides some resistance to passive stretching. Hypotonia thus manifests as diminished resistance to passive stretching. Hypotonia is not the same as muscle weakness, although the two conditions can co-exist. Evidence: PCS. Frequency: 6/6. Onset: Congenital onset (HP:0003577). (PMID:10973257)
- Global developmental delay (HP:0001263): A delay in the achievement of motor or mental milestones in the domains of development of a child, including motor skills, speech and language, cognitive skills, and social and emotional skills. This term should only be used to describe children younger than five years of age. Evidence: PCS. Frequency: 6/6. (PMID:10973257)
- 4-layered lissencephaly (HP:0006818): A form of lissencephaly in which the cortex is thickened and has four more or less disorganized layers rather than six normal layers resulting from incomplete neuronal migration during brain development. At neuropathological examination, a 4-layered cortex consists of an upper molecular layer, a second thin cellular layer containing pyramidal neurons usually observed in layer V, a third pale poorly cellular layer and a fourth thick deep layer made up of neurons which had failed to migrate. Radiologocally would manifest as agyria or pachygyria with cortical thickness greater than 10 mm. Evidence: PCS. (PMID:6476009)
- Hypoplasia of the pons (HP:0012110): Underdevelopment of the pons. Evidence: PCS. (PMID:10973257)
- Thick cerebral cortex (HP:0006891). Evidence: IEA. (OMIM:257320)
- Prominent nasal bridge (HP:0000426): Anterior positioning of the nasal root in comparison to the usual positioning for age. Evidence: TAS. (OMIM:257320)
- Lissencephaly (HP:0001339): A spectrum of malformations of cortical development caused by insufficient neuronal migration that subsumes the terms agyria, pachygyria and subcortical band heterotopia. See also neuropathological definitions for 2-, 3-, and 4-layered lissencephaly. Evidence: PCS. Frequency: 6/6. (PMID:10973257)
- Autosomal recessive inheritance (HP:0000007): A mode of inheritance that is observed for traits related to a gene encoded on one of the autosomes (i.e., the human chromosomes 1-22) in which a trait manifests in individuals with two pathogenic alleles, either homozygotes (two copies of the same mutant allele) or compound heterozygotes (whereby each copy of a gene has a distinct mutant allele). Evidence: PCS. (PMID:10973257)
- Lymphedema (HP:0001004): Localized fluid retention and tissue swelling caused by a compromised lymphatic system. Evidence: PCS. Onset: Congenital onset (HP:0003577). (PMID:10973257)
These phenotypes are associated with the disease Norman-Roberts syndrome (OMIM:257320).