- 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: PCS. Frequency: 1/1. (PMID:9621512)
- Opisthotonus (HP:0002179): Opisthotonus is defined as a dramatic abnormal posture due to spastic contraction of the extensor muscles of the neck, trunk, and lower extremities that produces a severe backward arching from neck to heel. In most cases, the trunk is elevated off the ground by a few inches. It is usually sudden in onset and can be sustained or repetitive. It can be considered a variant of decerebrate posturing involving a hyperextension of the neck, back, and limbs. Evidence: PCS. Frequency: 1/1. (PMID:9621512)
- Ketoacidosis (HP:0001993): Acidosis resulting from accumulation of ketone bodies. Evidence: PCS. Frequency: 1/1. (PMID:9621512)
- Childhood onset (HP:0011463): Onset of disease at the age of between 1 and 5 years. Evidence: PCS. Frequency: 1/2. (PMID:9621512)
- 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:9621512)
- Neonatal onset (HP:0003623): Onset of signs or symptoms of disease within the first 28 days of life. Evidence: PCS. Frequency: 1/2. (PMID:9621512)
These phenotypes are associated with the disease maple syrup urine disease type 2 (OMIM:620699).