- 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: 8/8. (PMID:27523599)
- Bradycardia (HP:0001662): A slower than normal heart rate (in adults, slower than 60 beats per minute). Evidence: PCS. Frequency: 6/6. (PMID:27523599)
- 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: PCS. Frequency: 9/9. (PMID:27523599)
- 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: 4/9. (PMID:27523599)
- 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: 9/9. (PMID:27523599)
- 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: 6/9. (PMID:27523599)
- 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: PCS. Frequency: 5/8. (PMID:27523599)
- Infantile onset (HP:0003593): Onset of signs or symptoms of disease between 28 days to one year of life. Evidence: PCS. (PMID:27523599)
- Nystagmus (HP:0000639): Rhythmic, involuntary oscillations of one or both eyes related to abnormality in fixation, conjugate gaze, or vestibular mechanisms. Evidence: PCS. Frequency: 6/7. (PMID:27523599)
- Retinal degeneration (HP:0000546): A nonspecific term denoting progressive loss of the retinal pigment epithelium (RPE) and/or neurosensory retinal cells. Evidence: PCS. Frequency: 2/9. (PMID:27523599)
- 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:27523599)
- Abnormal electroretinogram (HP:0000512): Any abnormality of the electrical responses of various cell types in the retina as measured by electroretinography. Evidence: PCS. Frequency: 3/9. (PMID:27523599)
- 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: 9/9. (PMID:27523599)
These phenotypes are associated with the disease gnb5-related intellectual disability-cardiac arrhythmia syndrome (OMIM:617173).