- Atypical behavior (HP:0000708): Atypical behavior is an abnormality in a person's actions that can be controlled or modulated by the will of the individual. While abnormal behaviors can be difficult to control, they are distinct from other abnormal actions that cannot be affected by the individual's will. Evidence: PCS. Frequency: 9/16. (PMID:22970919)
- Microcephaly (HP:0000252): Head circumference below 2 standard deviations below the mean for age and gender. Evidence: PCS. Frequency: 7/20. (PMID:22970919)
- Delayed speech and language development (HP:0000750): A degree of language development that is significantly below the norm for a child of a specified age. Evidence: PCS. Frequency: 15/15. (PMID:22970919)
- Seizure (HP:0001250): A seizure is an intermittent abnormality of nervous system physiology characterized by a transient occurrence of signs and/or symptoms due to abnormal excessive or synchronous neuronal activity in the brain. Evidence: PCS. Frequency: 8/22. (PMID:22970919)
- 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: 42/42. (PMID:22970919)
- 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: 10/21. (PMID:22970919)
- Abnormal facial shape (HP:0001999): An abnormal morphology (form) of the face or its components. Evidence: IEA. Frequency: Very frequent (HP:0040281). (OMIM:136570)
- Hypoplastic left ventricle (HP:0004383): A severe congenital heart defect characterized by underdevelopment of the left ventricle. Evidence: PCS. Frequency: 4/21. (PMID:22970919)
- Growth delay (HP:0001510): A deficiency or slowing down of growth pre- and postnatally. Evidence: PCS. Frequency: 9/22. (PMID:22970919)
These phenotypes are associated with the disease chromosome 16p12.1 deletion syndrome, 520kb (OMIM:136570).