- Hyperreflexia (HP:0001347): Hyperreflexia is the presence of hyperactive stretch reflexes of the muscles. Evidence: TAS. Frequency: Very frequent (HP:0040281). (ORPHA:415)
- Hyperammonemia (HP:0001987): An increased concentration of ammonia in the blood. Evidence: TAS. Frequency: Very frequent (HP:0040281). (ORPHA:415)
- Abnormal circulating citrulline concentration (HP:0011965): Any deviation from the normal concentration of citrulline in the blood circulation. Evidence: TAS. Frequency: Very frequent (HP:0040281). (ORPHA:415)
- Hyperornithinemia (HP:0012026): Increased concentration of ornithine in the blood. Evidence: TAS. Frequency: Very frequent (HP:0040281). (ORPHA:415)
- Neurodevelopmental delay (HP:0012758): Neurodevelopmental delay (NDD) refers to delays in the maturation of the brain and central nervous system; infants and young children with NDD may experience delays in the development of one or more skills including gross motor abilities, fine-motor coordination, language abilities and ability to solve increasingly complex problems. Evidence: TAS. Frequency: Very frequent (HP:0040281). (ORPHA:415)
- Cognitive impairment (HP:0100543): Abnormal cognition is characterized by deficits in thinking, reasoning, or remembering. Evidence: TAS. Frequency: Very frequent (HP:0040281). (ORPHA:415)
- 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: Frequent (HP:0040282). (ORPHA:415)
- Lethargy (HP:0001254): A state of fatigue, either physical or mental slowness and sluggishness, with difficulties in initiating or performing simple tasks. Distinguished from apathy which implies indifference and a lack of desire or interest in the task. A person with lethargy may have the desire, but not the energy to engage in personal or socially relevant tasks. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:415)
- Spastic paraplegia (HP:0001258): Complete loss of the ability to move the lower limbs accompanied by spasticity of the lower limbs. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:415)
- Confusion (HP:0001289): Lack of clarity and coherence of thought, perception, understanding, or action. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:415)
- Generalized hypotonia (HP:0001290): Generalized muscular hypotonia (abnormally low muscle tone). Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:415)
- Specific learning disability (HP:0001328): Impairment of certain skills such as reading or writing, coordination, self-control, or attention that interfere with the ability to learn. The impairment is not related to a global deficiency of intelligence. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:415)
- Decreased liver function (HP:0001410): Reduced ability of the liver to perform its functions. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:415)
- Failure to thrive (HP:0001508): Failure to thrive (FTT) refers to a child whose physical growth is substantially below the norm. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:415)
- Protein avoidance (HP:0002038). Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:415)
- Progressive cerebellar ataxia (HP:0002073). Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:415)
- Cerebral cortical atrophy (HP:0002120): Atrophy of the cortex of the cerebrum. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:415)
- Clonus (HP:0002169): A series of rhythmic and involuntary muscle contractions (at a frequency of about 5 to 7 Hz) that occur in response to an abruptly applied and sustained stretch. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:415)
- Hepatomegaly (HP:0002240): Abnormally increased size of the liver. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:415)
- Incoordination (HP:0002311): A deficit in coordination of muscle movements. Coordination is defined as the orchestrated movement of multiple body parts as required to accomplish intended actions, like walking. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:415)
- Impaired vibratory sensation (HP:0002495): A decrease in the ability to perceive vibration. Clinically, this is usually tested with a tuning fork which vibrates at 128 Hz and is applied to bony prominences such as the malleoli at the ankles or the metacarpal-phalangeal joints. There is a slow decay of vibration from the tuning fork. The degree of vibratory sense loss can be crudely estimated by counting the number of seconds that the examiner can perceive the vibration longer than the patient. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:415)
- Episodic vomiting (HP:0002572): Paroxysmal, recurrent episodes of vomiting. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:415)
- Tachypnea (HP:0002789): Very rapid breathing. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:415)
- Elevated circulating hepatic transaminase concentration (HP:0002910): Elevations of the levels of SGOT and SGPT in the serum. SGOT (serum glutamic oxaloacetic transaminase) and SGPT (serum glutamic pyruvic transaminase) are transaminases primarily found in the liver and heart and are released into the bloodstream as the result of liver or heart damage. SGOT and SGPT are used clinically mainly as markers of liver damage. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:415)
- Oroticaciduria (HP:0003218): An increased concentration of orotic acid in the urine. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:415)
- Acute encephalopathy (HP:0006846). Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:415)
- Abnormal pyramidal sign (HP:0007256): Functional neurological abnormalities related to dysfunction of the pyramidal tract. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:415)
- Speech apraxia (HP:0011098): A type of apraxia that is characterized by difficulty or inability to execute speech movements because of problems with coordination and motor problems, leading to incorrect articulation. An increase of errors with increasing word and phrase length may occur. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:415)
- Feeding difficulties (HP:0011968): Impaired ability to eat related to problems gathering food and getting ready to suck, chew, or swallow it. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:415)
- Hepatitis (HP:0012115): Inflammation of the liver. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:415)
- 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:415)
- Coma (HP:0001259): The complete absence of wakefulness and consciousness, which is evident through a lack of response to any form of external stimuli. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:415)
- Respiratory alkalosis (HP:0001950): Alkalosis due to excess loss of carbon dioxide from the body. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:415)
- Spastic gait (HP:0002064): Spasticity is manifested by increased stretch reflex which is intensified with movement velocity. This results in excessive and inappropriate muscle activation which can contribute to muscle hypertonia. Spastic gait is characterized by manifestations such as muscle hypertonia, stiff knee, and circumduction of the leg. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:415)
- Generalized myoclonic seizure (HP:0002123): A generalized myoclonic seizure is a type of generalized motor seizure characterized by bilateral, sudden, brief (<100 ms) involuntary single or multiple contraction of muscles or muscle groups of variable topography (axial, proximal limb, distal). Myoclonus is less regularly repetitive and less sustained than is clonus. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:415)
- Abnormality of the coagulation cascade (HP:0003256): An abnormality of the coagulation cascade, which is comprised of the contact activation pathway (also known as the intrinsic pathway) and the tissue factor pathway (also known as the extrinsic pathway) as well as cofactors and regulators. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:415)
- Multifocal cerebral white matter abnormalities (HP:0007052). Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:415)
- Chorioretinal atrophy (HP:0000533): Atrophy (wasting) of the choroid and retinal layers of the fundus. Evidence: TAS. Frequency: Very rare (HP:0040284). (ORPHA:415)
- Hepatic failure (HP:0001399). Evidence: TAS. Frequency: Very rare (HP:0040284). (ORPHA:415)
- Chorioretinal hypopigmentation (HP:0040030): Focal or global or heterogeneous loss of choroidal and retinal pigment epithelium (RPE) pigmentation in the absence of atrophy. Evidence: TAS. Frequency: Very rare (HP:0040284). (ORPHA:415)
These phenotypes are associated with the disease Hyperornithinemia-hyperammonemia-homocitrullinuria syndrome (ORPHA:415).