- Narrow forehead (HP:0000341): Width of the forehead or distance between the frontotemporales is more than two standard deviations below the mean (objective); or apparently narrow intertemporal region (subjective). Evidence: PCS. Frequency: 1/12. (PMID:19716111)
- Poor speech (HP:0002465). Evidence: PCS. Frequency: 3/12. (PMID:19716111)
- Medial flaring of the eyebrow (HP:0010747): An abnormal distribution of eyebrow hair growth in the medial direction. Evidence: PCS. Frequency: 1/12. (PMID:19716111)
- Generalized non-motor (absence) seizure (HP:0002121): A generalized non-motor (absence) seizure is a type of a type of dialeptic seizure that is of electrographically generalized onset. It is a generalized seizure characterized by an interruption of activities, a blank stare, and usually the person will be unresponsive when spoken to. Any ictal motor phenomena are minor in comparison to these non-motor features. Evidence: PCS. Frequency: 4/12. Onset: Childhood onset (HP:0011463). (PMID:19716111)
- 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: 3/12. (PMID:19716111)
- Low posterior hairline (HP:0002162): Hair on the neck extends more inferiorly than usual. Evidence: PCS. Frequency: 1/12. (PMID:19716111)
- Widened subarachnoid space (HP:0012704): An increase in size of the anatomic space between the arachnoid membrane and pia mater. Evidence: PCS. Frequency: 2/6. (PMID:19716111)
- Excessive shyness (HP:0100962): Atypically high degree of awkwardness or apprehension experienced when approaching or being approached by others. Evidence: PCS. Frequency: 2/12. (PMID:19716111)
- Smooth philtrum (HP:0000319): Flat skin surface, with no ridge formation in the central region of the upper lip between the nasal base and upper vermilion border. Evidence: PCS. Frequency: 4/12. (PMID:19716111)
- Hoarse voice (HP:0001609): Hoarseness refers to a change in the pitch or quality of the voice, with the voice sounding weak, very breathy, scratchy, or husky. Evidence: PCS. Frequency: 1/12. (PMID:19716111)
- 2-3 toe cutaneous syndactyly (HP:0005709). Evidence: PCS. Frequency: 1/12. (PMID:19716111)
- X-linked dominant inheritance (HP:0001423): A mode of inheritance that is observed for dominant traits related to a gene encoded on the X chromosome. In the context of medical genetics, X-linked dominant disorders tend to manifest very severely in affected males. The severity of manifestation in females may depend on the degree of skewed X inactivation. Evidence: PCS. (PMID:19716111)
- Pes planus (HP:0001763): A foot where the longitudinal arch of the foot is in contact with the ground or floor when the individual is standing; or, in a patient lying supine, a foot where the arch is in contact with the surface of a flat board pressed against the sole of the foot by the examiner with a pressure similar to that expected from weight bearing; or, the height of the arch is reduced. Evidence: PCS. Frequency: 3/12. (PMID:19716111)
- Intellectual disability (HP:0001249): The term intellectual disability or intellectual developmental disorder is used to describe significantly sub-average intellectual and adaptive functioning based on clinical assessment and as measured by individually administered, appropriately normed, standardized and validated tests of intellectual functioning and adaptive behavior, with onset during the developmental period from infancy through adolescence. Evidence: PCS. Frequency: 12/12. (PMID:19716111)
- Posteriorly rotated ears (HP:0000358): A type of abnormal location of the ears in which the position of the ears is characterized by posterior rotation (the superior part of the ears is rotated towards the back of the head, and the inferior part of the ears towards the front). Evidence: PCS. Frequency: 1/12. Onset: Congenital onset (HP:0003577). (PMID:19716111)
- Overfolded helix (HP:0000396): A condition in which the helix is folded over to a greater degree than normal. That is, excessive curling of the helix edge, whereby the free edge is parallel to the plane of the ear. Evidence: PCS. Frequency: 1/12. (PMID:19716111)
- Downslanted palpebral fissures (HP:0000494): The palpebral fissure inclination is more than two standard deviations below the mean. Evidence: PCS. Frequency: 2/12. (PMID:19716111)
- 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: 12/12. (PMID:19716111)
- EEG abnormality (HP:0002353): Abnormality observed by electroencephalogram (EEG), which is used to record of the brain's spontaneous electrical activity from multiple electrodes placed on the scalp. Evidence: PCS. (PMID:19716111)
- Thick eyebrow (HP:0000574): Increased density/number and/or increased diameter of eyebrow hairs. Evidence: PCS. Frequency: 2/12. (PMID:19716111)
- Thin vermilion border (HP:0000233): Height of the vermilion of the medial part of the lip more than 2 SD below the mean, or apparently reduced height of the vermilion of the lip in the frontal view. The vermilion is the red part of the lips (and confusingly, the vermilion itself is also often referred to as being equivalent the lips). Evidence: PCS. Frequency: 4/12. (PMID:19716111)
- Pes cavus (HP:0001761): An increase in height of the medial longitudinal arch of the foot that does not flatten on weight bearing (i.e., a distinctly hollow form of the sole of the foot when it is bearing weight). Evidence: PCS. Frequency: 3/12. (PMID:19716111)
- Underdeveloped nasal alae (HP:0000430): Thinned, deficient, or excessively arched ala nasi. Evidence: PCS. Frequency: 2/12. (PMID:19716111)
- Dysarthria (HP:0001260): Dysarthric speech is a general description referring to a neurological speech disorder characterized by poor articulation. Depending on the involved neurological structures, dysarthria may be further classified as spastic, flaccid, ataxic, hyperkinetic and hypokinetic, or mixed. Evidence: PCS. Frequency: 2/12. (PMID:19716111)
- Midface retrusion (HP:0011800): Posterior positions and/or vertical shortening of the infraorbital and perialar regions, or increased concavity of the face and/or reduced nasolabial angle. Evidence: PCS. Frequency: 2/12. (PMID:19716111)
- Precocious puberty (HP:0000826): The onset of secondary sexual characteristics before a normal age. Although it is difficult to define normal age ranges because of the marked variation with which puberty begins in normal children, precocious puberty can be defined as the onset of puberty before the age of 8 years in girls or 9 years in boys. Evidence: PCS. Frequency: 7/11. (PMID:19716111)
- Prominent nasal bridge (HP:0000426): Anterior positioning of the nasal root in comparison to the usual positioning for age. Evidence: PCS. Frequency: 3/12. (PMID:19716111)
- Dolichocephaly (HP:0000268): An abnormality of skull shape characterized by a increased anterior-posterior diameter, i.e., an increased antero-posterior dimension of the skull. Cephalic index less than 76%. Alternatively, an apparently increased antero-posterior length of the head compared to width. Often due to premature closure of the sagittal suture. Evidence: PCS. Frequency: 1/12. (PMID:19716111)
- Frontal bossing (HP:0002007): Bilateral bulging of the lateral frontal bone prominences with relative sparing of the midline. Evidence: PCS. Frequency: 1/12. (PMID:19716111)
- Synophrys (HP:0000664): Meeting of the medial eyebrows in the midline. Evidence: PCS. Frequency: 2/12. (PMID:19716111)
- Short philtrum (HP:0000322): Distance between nasal base and midline upper lip vermilion border more than 2 SD below the mean. Alternatively, an apparently decreased distance between nasal base and midline upper lip vermilion border. Evidence: PCS. Frequency: 3/12. (PMID:19716111)
- Widely-spaced incisors (HP:0006304). Evidence: PCS. Frequency: 1/12. (PMID:19716111)
- Hypernasal speech (HP:0001611): A type of speech characterized by the presence of an abnormally increased nasal airflow during speech associated with structural abnormality of the nasal passages. Evidence: PCS. Frequency: 1/12. (PMID:19716111)
These phenotypes are associated with the disease chromosome Xp11.23-p11.22 duplication syndrome (OMIM:300801).