- 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: TAS. Frequency: Very frequent (HP:0040281). (ORPHA:324262)
- Hyperreflexia (HP:0001347): Hyperreflexia is the presence of hyperactive stretch reflexes of the muscles. Evidence: TAS. Frequency: Very frequent (HP:0040281). (ORPHA:324262)
- Gait ataxia (HP:0002066): A type of ataxia characterized by the impairment of the ability to coordinate the movements required for normal walking. Gait ataxia is characteirzed by a wide-based staggering gait with a tendency to fall. Evidence: TAS. Frequency: Very frequent (HP:0040281). (ORPHA:324262)
- Difficulty standing (HP:0003698). Evidence: TAS. Frequency: Very frequent (HP:0040281). (ORPHA:324262)
- Esotropia (HP:0000565): A form of strabismus with one or both eyes turned inward ('crossed') to a relatively severe degree, usually defined as 10 diopters or more. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:324262)
- Hypometric saccades (HP:0000571): Saccadic undershoot, i.e., a saccadic eye movement that has less than the magnitude that would be required to gain fixation of the object. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:324262)
- Dysmetria (HP:0001310): A type of ataxia characterized by the inability to carry out movements with the correct range and motion across the plane of more than one joint related to incorrect estimation of the distances required for targeted movements. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:324262)
- Dysdiadochokinesis (HP:0002075): A type of ataxia characterized by the impairment of the ability to perform rapidly alternating movements, such as pronating and supinating his or her hand on the dorsum of the other hand as rapidly as possible. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:324262)
- Abnormal speech pattern (HP:0002167): An abnormality in the sound (volume) or cadence (rate) of speech. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:324262)
- Limb dysmetria (HP:0002406): A type of dysmetria involving the limbs. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:324262)
- Functional motor deficit (HP:0004302). Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:324262)
- Abnormality of ocular abduction (HP:0011347): An abnormality involving the movement of the eye outwards. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:324262)
- Ptosis (HP:0000508): The upper eyelid margin is positioned 3 mm or more lower than usual and covers the superior portion of the iris (objective); or, the upper lid margin obscures at least part of the pupil (subjective). Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:324262)
- 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: Occasional (HP:0040283). (ORPHA:324262)
- Polyneuropathy (HP:0001271): A generalized disorder of peripheral nerves. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:324262)
- Absent speech (HP:0001344): Complete lack of development of speech and language abilities. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:324262)
- Gaze-evoked horizontal nystagmus (HP:0007979): Horizontal nystagmus made apparent by looking to the right or to the left. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:324262)
These phenotypes are associated with the disease Autosomal recessive congenital cerebellar ataxia due to MGLUR1 deficiency (ORPHA:324262).