- 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:610006)
- Microcephaly (HP:0000252): Head circumference below 2 standard deviations below the mean for age and gender. Evidence: IEA. (OMIM:610006)
- Hypothermia (HP:0002045): Reduced body temperature due to failed thermoregulation. Evidence: IEA. (OMIM:610006)
- 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:610006)
- 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: 1/1. (PMID:11013134)
- 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. (OMIM:610006)
- Infantile onset (HP:0003593): Onset of signs or symptoms of disease between 28 days to one year of life. Evidence: IEA. (OMIM:610006)
- Motor delay (HP:0001270): A type of Developmental delay characterized by a delay in acquiring motor skills. Evidence: PCS. Frequency: 1/1. (PMID:11013134)
- 2-ethylhydracylic aciduria (HP:0033220): An increased concentration of 2-ethylhydracylic acid in the urine. Evidence: PCS. Frequency: 1/1. (PMID:11013134)
- Childhood onset (HP:0011463): Onset of disease at the age of between 1 and 5 years. Evidence: PCS. Frequency: 1/1. (PMID:11013134)
- Hypoglycemia (HP:0001943): A decreased concentration of glucose in the blood. Evidence: IEA. (OMIM:610006)
- 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:11013134)
- Apneic episodes in infancy (HP:0005949): Recurrent episodes of apnea occurring during infancy. Evidence: IEA. (OMIM:610006)
- Generalized amyotrophy (HP:0003700): Generalized (diffuse, unlocalized) amyotrophy (muscle atrophy) affecting multiple muscles. Evidence: PCS. Frequency: 1/1. (PMID:11013134)
- Exotropia (HP:0000577): A form of strabismus with one or both eyes deviated outward. Evidence: IEA. (OMIM:610006)
These phenotypes are associated with the disease 2-methylbutyryl-CoA dehydrogenase deficiency (OMIM:610006).