- 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: TAS. Frequency: Very frequent (HP:0040281). (ORPHA:542306)
- Abnormality of the cardiovascular system (HP:0001626): Any abnormality of the cardiovascular system. Evidence: TAS. Frequency: Very frequent (HP:0040281). (ORPHA:542306)
- Abnormal electroretinogram (HP:0000512): Any abnormality of the electrical responses of various cell types in the retina as measured by electroretinography. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:542306)
- Nystagmus (HP:0000639): Rhythmic, involuntary oscillations of one or both eyes related to abnormality in fixation, conjugate gaze, or vestibular mechanisms. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:542306)
- 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: TAS. Frequency: Frequent (HP:0040282). (ORPHA:542306)
- 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: TAS. Frequency: Frequent (HP:0040282). (ORPHA:542306)
- 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: TAS. Frequency: Frequent (HP:0040282). (ORPHA:542306)
- Absent speech (HP:0001344): Complete lack of development of speech and language abilities. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:542306)
- Bradycardia (HP:0001662): A slower than normal heart rate (in adults, slower than 60 beats per minute). Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:542306)
- Gastroesophageal reflux (HP:0002020): A condition in which the stomach contents leak backwards from the stomach into the esophagus through the lower esophageal sphincter. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:542306)
- Ventricular escape rhythm (HP:0005155): A ventricular escape rhythm occurs whenever higher-lever pacemakers in AV junction or sinus node fail to control ventricular activation. Escape rate is usually 20-40 bpm, often associated with broad QRS complexes (at least 120 ms). Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:542306)
- Severe intellectual disability (HP:0010864): Severe intellectual disability (ID) is defined as a type of ID characterized by severely sub-average adaptive functioning and intellectual functioning, with an intelligence quotient (IQ) the range of 20-34. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:542306)
- Arrhythmia (HP:0011675): Any cardiac rhythm other than the normal sinus rhythm. Such a rhythm may be either of sinus or ectopic origin and either regular or irregular. An arrhythmia may be due to a disturbance in impulse formation or conduction or both. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:542306)
- Sick sinus syndrome (HP:0011704): An abnormality involving the generation of the action potential by the sinus node and is characterized by an atrial rate inappropriate for physiological requirements. Manifestations include severe sinus bradycardia, sinus pauses or arrest, sinus node exit block, chronic atrial tachyarrhythmias, alternating periods of atrial bradyarrhythmias and tachyarrhythmias, and inappropriate responses of heart rate during exercise or stress. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:542306)
- Retinal degeneration (HP:0000546): A nonspecific term denoting progressive loss of the retinal pigment epithelium (RPE) and/or neurosensory retinal cells. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:542306)
- Keratoconus (HP:0000563): A cone-shaped deformity of the cornea characterized by the presence of corneal distortion secondary to thinning of the apex. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:542306)
- Reduced eye contact (HP:0000817): A reduced frequency or duration of eye contact. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:542306)
- Patent foramen ovale (HP:0001655): Failure of the foramen ovale to seal postnatally, leaving a potential conduit between the left and right cardiac atria. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:542306)
- Poor head control (HP:0002421): Difficulty to maintain correct position of the head while standing or sitting. Infant head lag is observed when the head seems to flop around or lags posteriorly behind the trunk. Several articles have maintained that head lag should be absent by age 3 to 4 months. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:542306)
- Hypsarrhythmia (HP:0002521): Hypsarrhythmia is abnormal interictal high amplitude waves and a background of irregular spikes. There is continuous (during wakefulness), high-amplitude (>200 Hz), generalized polymorphic slowing with no organized background and multifocal spikes demonstrated by electroencephalography (EEG). Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:542306)
- Poor fine motor coordination (HP:0007010): An abnormality of the ability (skills) to perform a precise movement of small muscles with the intent to perform a specific act. Fine motor skills are required to mediate movements of the wrists, hands, fingers, feet, and toes. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:542306)
- Prolonged PR interval (HP:0012248): Increased time for the PR interval (beginning of the P wave to the beginning of the QRS complex). Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:542306)
These phenotypes are associated with the disease GNB5-related intellectual disability-cardiac arrhythmia syndrome (ORPHA:542306).