- 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:65287)
- 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:65287)
- 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:65287)
- 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: Frequent (HP:0040282). (ORPHA:65287)
- Reduced hepatic beta-ureidopropionase activity (HP:6000082): Activity of beta-ureidopropionase in the liver below the lower limit of normal. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:65287)
- Elevated urinary dihydrouracil level (HP:6000118): The amount of dihydrouracil in the urine, normalized for urine concentration, is above the upper limit of normal. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:65287)
- Elevated urinary dihydrothymine level (HP:6000119): The amount of dihydrothymine in the urine, normalized for urine concentration, is above the upper limit of normal. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:65287)
- Elevated urinary N-carbamoyl-beta-alanine level (HP:6000279): The amount of N-carbamoyl-beta-alanine present in urine, when adjusted for urine concentration, is above the upper limit of normal. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:65287)
- Elevated urinary N-carbamyl-beta-aminoisobutyric acid level (HP:6000623): The amount of N-carbamyl-beta-aminoisobutyric acid in the urine, normalized for urine concentration, is above the upper limit of normal. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:65287)
- Microcephaly (HP:0000252): Head circumference below 2 standard deviations below the mean for age and gender. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:65287)
- Autism (HP:0000717): Autism is a neurodevelopmental disorder characterized by impaired social interaction and communication, and by restricted and repetitive behavior. Autism begins in childhood. It is marked by the presence of markedly abnormal or impaired development in social interaction and communication and a markedly restricted repertoire of activity and interest. Manifestations of the disorder vary greatly depending on the developmental level and chronological age of the individual (DSM-IV). Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:65287)
- 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: Occasional (HP:0040283). (ORPHA:65287)
- Growth delay (HP:0001510): A deficiency or slowing down of growth pre- and postnatally. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:65287)
- Cerebral atrophy (HP:0002059): Atrophy (wasting, decrease in size of cells or tissue) affecting the cerebrum. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:65287)
- Cortical dysplasia (HP:0002539): The presence of developmental dysplasia of the cerebral cortex. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:65287)
- Delayed myelination (HP:0012448): Delayed myelination. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:65287)
These phenotypes are associated with the disease Beta-ureidopropionase deficiency (ORPHA:65287).