- 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: IEA. (OMIM:248600)
- Hypertonia (HP:0001276): A condition in which there is increased muscle tone so that arms or legs, for example, are stiff and difficult to move. Evidence: IEA. (OMIM:248600)
- Vomiting (HP:0002013): Forceful ejection of the contents of the stomach through the mouth by means of a series of involuntary spasmic contractions. Evidence: IEA. (OMIM:248600)
- 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: IEA. (OMIM:248600)
- Increased level of hippuric acid in urine (HP:0410066): An increase in the level of hippuric acid in the urine. Evidence: PCS. Frequency: 20/20. (PMID:22626821;PMID:19551947)
- Positive 2,4-dinitrophenylhydrazine urine test (HP:6000124): Positive (abnormal) result of the 2,4-dinitrophenylhydrazine urine test, which indicates the presence of alpha-ketoacids in the urine. Evidence: PCS. (PMID:32491705)
- 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: IEA. (OMIM:248600)
- Ataxia (HP:0001251): Ataxia refers to impaired coordination of voluntary muscle movement. Cerebellar ataxia refers to ataxia due to dysfunction of the cerebellum. This causes a variety of elementary neurological deficits including asynergy (lack of coordination between muscles, limbs and joints), dysmetria (lack of ability to judge distances that can lead to under- or overshoot in grasping movements), and dysdiadochokinesia (inability to perform rapid movements requiring antagonizing muscle groups to be switched on and off repeatedly). Evidence: IEA. (OMIM:248600)
- Generalized hypotonia (HP:0001290): Generalized muscular hypotonia (abnormally low muscle tone). Evidence: TAS. (OMIM:248600)
- Cerebral edema (HP:0002181): Abnormal accumulation of fluid in the brain. Evidence: IEA. (OMIM:248600)
- Recurrent (HP:0031796): Applies to a sign, symptom or manifestation that occurs multiple times separated by intervals in which the sign, symptom, or manifestation is not present. Evidence: IEA. (OMIM:248600)
- Hallucinations (HP:0000738): Perceptions in a conscious and awake state that, in the absence of external stimuli, have qualities of real perception. These perceptions are vivid, substantial, and located in external objective space. Evidence: IEA. (OMIM:248600)
- Growth abnormality (HP:0001507). Evidence: IEA. (OMIM:248600)
- Elevated circulating L-alloisoleucine concentration (HP:0033155): Abnormally increased concentration of L-alloisoleucine in the blood circulation. Evidence: PCS. (PMID:7413299)
- 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: IEA. (OMIM:248600)
- Hypoglycemia (HP:0001943): A decreased concentration of glucose in the blood. Evidence: IEA. (OMIM:248600)
- Elevated circulating branched chain amino acid concentration (HP:0008344): Concentration of a branched chain amino acid in the blood above the upper limit of normal. Evidence: IEA. (OMIM:248600)
- Feeding difficulties in infancy (HP:0008872): Impaired feeding performance of an infant as manifested by difficulties such as weak and ineffective sucking, brief bursts of sucking, and falling asleep during sucking. There may be difficulties with chewing or maintaining attention. Evidence: IEA. (OMIM:248600)
- Ketosis (HP:0001946): Presence of elevated levels of ketone bodies in the body. Evidence: IEA. (OMIM:248600)
- Reduced branched-chain alpha-keto acid dehydrogenase activity in cultured fibroblasts (HP:4000207): Activity of branched-chain alpha-keto acid dehydrogenase complex (EC 1.2.4.4) below the lower limit of normal in cultured fibroblasts. Evidence: TAS. (OMIM:248600)
- 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: IEA. (OMIM:248600)
- Pancreatitis (HP:0001733): The presence of inflammation in the pancreas. Evidence: IEA. (OMIM:248600)
- 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: IEA. (OMIM:248600)
- Lactic acidosis (HP:0003128): An abnormal buildup of lactic acid in the body, leading to acidification of the blood and other bodily fluids. Evidence: TAS. (OMIM:248600)
These phenotypes are associated with the disease maple syrup urine disease type 1A (OMIM:248600).