- 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: 4/11. Onset: Neonatal onset (HP:0003623). (PMID:12891654)
- Exaggerated startle response (HP:0002267): An exaggerated startle reaction in response to a sudden unexpected visual or acoustic stimulus, or a quick movement near the face. Evidence: PCS. Frequency: 7/11. (PMID:12891654)
- Reduced circulating aromatic L-amino acid decarboxylase activity (HP:6000037): The activity of aromatic L-amino acid decarboxylase (also known as DOPA decarboxylase, tryptophan decarboxylase, and 5-hydroxytryptophan decarboxylase) in the blood circulation is below the lower limit of normal. Evidence: TAS. (OMIM:608643)
- Sleep disturbance (HP:0002360): An abnormal pattern in the quality, quantity, or characteristics of sleep. Evidence: PCS. Frequency: 7/11. (PMID:12891654)
- Gastroesophageal reflux (HP:0002020): A condition in which the stomach contents leak backwards from the stomach into the esophagus through the lower esophageal sphincter. Evidence: PCS. Frequency: 9/11. (PMID:12891654)
- Infantile onset (HP:0003593): Onset of signs or symptoms of disease between 28 days to one year of life. Evidence: IEA. (OMIM:608643)
- Elevated urinary vanillactic acid level (HP:6001002): The amount of vanillactic acid in the urine, normalized for urine concentration, is above the upper limit of normal. Evidence: TAS. (OMIM:608643)
- Tongue thrusting (HP:0100703): Pressing forward of the tongue in the mouth, a retained motoric habit from infantile swallowing patterns. Evidence: PCS. Frequency: 9/11. (PMID:12891654)
- Irritability (HP:0000737): An emotional state characterized by negative feelings of heightened frustration, annoyance, or feeling upset, often triggered by internal factors (e.g., fatigue, hunger, unfulfilled desires) or external factors (e.g., social or environmental challenges). Irritability may be unpredictable, and is accompanied by a lowered threshold for emotional reactivity and observable features (speech, facial expressions, or psychomotor activity). Evidence: PCS. Frequency: 10/11. (PMID:12891654)
- Miosis (HP:0000616): Abnormal (non-physiological) constriction of the pupil. Evidence: IEA. (OMIM:608643)
- Emotional lability (HP:0000712): Unstable emotional experiences and frequent mood changes; emotions that are easily aroused, intense, and/or disproportionate to events and circumstances. Evidence: PCS. Frequency: 10/11. (PMID:12891654)
- 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: PCS. Frequency: 5/11. Onset: Infantile onset (HP:0003593). (PMID:12891654)
- Hyperhidrosis (HP:0000975): Abnormal excessive perspiration (sweating) despite the lack of appropriate stimuli like hot and humid weather. Evidence: IEA. (OMIM:608643)
- Hypotension (HP:0002615): Low Blood Pressure, vascular hypotension. Evidence: IEA. (OMIM:608643)
- Nasal congestion (HP:0001742): Reduced ability to pass air through the nasal cavity often leading to mouth breathing. Evidence: PCS. Frequency: 8/11. (PMID:12891654)
- Temperature instability (HP:0005968): Disordered thermoregulation characterized by an impaired ability to maintain a balance between heat production and heat loss, with resulting instability of body temperature. Evidence: IEA. (OMIM:608643)
- Constipation (HP:0002019): Infrequent or difficult evacuation of feces. Evidence: PCS. Frequency: 5/11. (PMID:12891654)
- Hyperreflexia (HP:0001347): Hyperreflexia is the presence of hyperactive stretch reflexes of the muscles. Evidence: PCS. Frequency: 8/11. (PMID:12891654)
- Limb tremor (HP:0200085). Evidence: PCS. Frequency: 7/11. (PMID:12891654)
- Decreased CSF homovanillic acid concentration (HP:0003785): Decreased concentration of homovanillic acid (HVA) in the cerebrospinal fluid. HVA is a metabolite of dopamine. Evidence: PCS. (PMID:12891654)
- Diarrhea (HP:0002014): Abnormally increased frequency (usually defined as three or more) loose or watery bowel movements a day. Evidence: PCS. Frequency: 5/11. (PMID:12891654)
- Intermittent hypothermia (HP:0005964): Episodes of reduced body temperature. Evidence: IEA. (OMIM:608643)
- Axial hypotonia (HP:0008936): Muscular hypotonia (abnormally low muscle tone) affecting the musculature of the trunk. Evidence: PCS. Frequency: 11/11. Onset: Infantile onset (HP:0003593). (PMID:12891654)
- Torticollis (HP:0000473): Involuntary contractions of the neck musculature resulting in an abnormal posture of or abnormal movements of the head. Evidence: PCS. Frequency: 7/11. (PMID:12891654)
- Babinski sign (HP:0003487): Upturning of the big toe (and sometimes fanning of the other toes) in response to stimulation of the sole of the foot. If the Babinski sign is present it can indicate damage to the corticospinal tract. Evidence: IEA. (OMIM:608643)
- Choreoathetosis (HP:0001266): Involuntary movements characterized by both athetosis (inability to sustain muscles in a fixed position) and chorea (widespread jerky arrhythmic movements). Evidence: IEA. (OMIM:608643)
- Abnormality of the face (HP:0000271): An abnormality of the face. Evidence: IEA. (OMIM:608643)
- Limb dystonia (HP:0002451): A type of dystonia (abnormally increased muscular tone causing fixed abnormal postures) that affects muscles of the limbs. Evidence: PCS. Frequency: 11/11. (PMID:12891654)
- Diminished movement (HP:0002374). Evidence: PCS. Frequency: 11/11. (PMID:12891654)
- 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: IEA. (OMIM:608643)
- Oculogyric crisis (HP:0010553): An acute dystonic reaction with blepharospasm, periorbital twitches, and protracted fixed staring episodes. There may be a maximal upward deviation of the eyes in the sustained fashion. Oculogyric crisis can be triggered by a number of factors including neuroleptic medications. Evidence: PCS. Frequency: 11/11. (PMID:12891654)
- Limb hypertonia (HP:0002509). Evidence: PCS. Frequency: 11/11. Onset: Infantile onset (HP:0003593). (PMID:12891654)
- Ptosis (HP:0000508): The upper eyelid margin is positioned 3 mm or more lower than usual and covers the superior portion of the iris (objective); or, the upper lid margin obscures at least part of the pupil (subjective). Evidence: PCS. Frequency: 5/11. (PMID:12891654)
- 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:608643)
- Cardiorespiratory arrest (HP:0006543). Evidence: PCS. Frequency: 2/11. (PMID:12891654)
- Athetosis (HP:0002305): A slow, continuous, involuntary writhing movement that prevents maintenance of a stable posture. Athetosis involves continuous smooth movements that appear random and are not composed of recognizable sub-movements or movement fragments. In contrast to chorea, in athetosis, the same regions of the body are repeatedly involved. Athetosis may worsen with attempts at movement of posture, but athetosis can also occur at rest. Evidence: PCS. Frequency: 11/11. (PMID:12891654)
- Apnea (HP:0002104): Lack of breathing with no movement of the respiratory muscles and no exchange of air in the lungs. This term refers to a disposition to have recurrent episodes of apnea rather than to a single event. Evidence: PCS. Frequency: 6/11. (PMID:12891654)
- Myoclonus (HP:0001336): Very brief, involuntary random muscular contractions occurring at rest, in response to sensory stimuli, or accompanying voluntary movements. Evidence: PCS. Frequency: 8/11. (PMID:12891654)
- Blepharospasm (HP:0000643): A focal dystonia that affects the muscles of the eyelids and brow, associated with involuntary recurrent spasm of both eyelids. Evidence: PCS. Frequency: 5/11. (PMID:12891654)
These phenotypes are associated with the disease aromatic L-amino acid decarboxylase deficiency (OMIM:608643).