- Atypical behavior (HP:0000708): Atypical behavior is an abnormality in a person's actions that can be controlled or modulated by the will of the individual. While abnormal behaviors can be difficult to control, they are distinct from other abnormal actions that cannot be affected by the individual's will. Evidence: TAS. Frequency: Very frequent (HP:0040281). (ORPHA:217253)
- Short attention span (HP:0000736): Reduced attention span characterized by distractibility and impulsivity. Evidence: TAS. Frequency: Very frequent (HP:0040281). (ORPHA:217253)
- 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: Very frequent (HP:0040281). (ORPHA:217253)
- Confusion (HP:0001289): Lack of clarity and coherence of thought, perception, understanding, or action. Evidence: TAS. Frequency: Very frequent (HP:0040281). (ORPHA:217253)
- Memory impairment (HP:0002354): An impairment of memory as manifested by a reduced ability to remember things such as dates and names, and increased forgetfulness. Evidence: TAS. Frequency: Very frequent (HP:0040281). (ORPHA:217253)
- CSF pleocytosis (HP:0012229): An increased white blood cell count in the cerebrospinal fluid. Evidence: TAS. Frequency: Very frequent (HP:0040281). (ORPHA:217253)
- Anti-NMDA receptor antibody positivity (HP:0032264): The presence of autoantibodies (immunoglobulins) in the serum that react against the NMDA (N-methyl-D-aspartate)-type glutamate receptor. Evidence: TAS. Frequency: Very frequent (HP:0040281). (ORPHA:217253)
- CSF anti-NMDA receptor antibody positivity (HP:0032266): The presence of autoantibodies (immunoglobulins) in the cerebrospinal fluid (CSF) that react against the NMDA (N-methyl-D-aspartate)-type glutamate receptor. Evidence: TAS. Frequency: Very frequent (HP:0040281). (ORPHA:217253)
- 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: TAS. Frequency: Frequent (HP:0040282). (ORPHA:217253)
- Anxiety (HP:0000739): Intense feelings of nervousness, tension, or panic often arise in response to interpersonal stresses. There is worry about the negative effects of past unpleasant experiences and future negative possibilities. Individuals may feel fearful, apprehensive, or threatened by uncertainty, and they may also have fears of falling apart or losing control. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:217253)
- Delusion (HP:0000746): A delusion is a fixed false belief held despite evidence to the contrary. The term delusion broadly encompasses all false judgments that possess the following external characteristics to a significant, albeit unspecified, extent: (1) they are held with an exceptional level of conviction, accompanied by an unparalleled subjective certainty; (2) there is an inability to consider alternative experiences or compelling counter-arguments; (3) the content of the belief is impossible. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:217253)
- Fever (HP:0001945): Body temperature elevated above the normal range. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:217253)
- Vomiting (HP:0002013): Forceful ejection of the contents of the stomach through the mouth by means of a series of involuntary spasmic contractions. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:217253)
- Diarrhea (HP:0002014): Abnormally increased frequency (usually defined as three or more) loose or watery bowel movements a day. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:217253)
- Headache (HP:0002315): Cephalgia, or pain sensed in various parts of the head, not confined to the area of distribution of any nerve. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:217253)
- Involuntary movements (HP:0004305): Involuntary contractions of muscle leading to involuntary movements of extremities, neck, trunk, or face. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:217253)
- EEG with temporal sharp slow waves (HP:0011289): EEG with sharp slow waves in the temporal region. Sharp slow waves are focal sharp transient waves of a duration between 80 and 200 msec followed by a slow wave. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:217253)
- Ovarian teratoma (HP:0012226): The presence of a teratoma in the ovary. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:217253)
- Abnormal autonomic nervous system physiology (HP:0012332): A functional abnormality of the autonomic nervous system. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:217253)
- Dyskinesia (HP:0100660): A movement disorder which consists of effects including diminished voluntary movements and the presence of involuntary movements. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:217253)
- Mania (HP:0100754): A state of abnormally elevated or irritable mood, arousal, and/or energy levels. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:217253)
- Insomnia (HP:0100785): Persistent difficulty in starting or maintaining sleep, or waking up earlier than desired, despite having adequate opportunities and conditions for sleep. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:217253)
- Psychosis (HP:0000709): A condition characterized by changes in personality and thought patterns, often accompanied by hallucinations and delusional beliefs, is known as psychosis. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:217253)
- Agitation (HP:0000713): A state of excessive motor activity that is associated with mental distress or a feeling of substantial unease or inner tension. Distinguished from restlessness by the increased level of emotional distress and negative intensity of the experience. Agitation has a significant level of physical activity that is typically threatening to the self or others. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:217253)
- Depression (HP:0000716): Frequently experiencing feelings of being down, miserable, and/or hopeless; struggling to recover from these moods; having a pessimistic outlook on the future; feeling a pervasive sense of shame; having a low self-worth; experiencing thoughts of suicide and engaging in suicidal behavior. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:217253)
- Motor stereotypy (HP:0000733): Use of the same abnormal action in response to certain triggers or at random. They may be used as a way to regulate one's internal state but must otherwise have no apparent functional purpose. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:217253)
- Choreoathetosis (HP:0001266): Involuntary movements characterized by both athetosis (inability to sustain muscles in a fixed position) and chorea (widespread jerky arrhythmic movements). Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:217253)
- Orthostatic hypotension (HP:0001278): A form of hypotension characterized by a sudden fall in blood pressure that occurs when a person assumes a standing position. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:217253)
- Dystonia (HP:0001332): An abnormally increased muscular tone that causes fixed abnormal postures. There is a slow, intermittent twisting motion that leads to exaggerated turning and posture of the extremities and trunk. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:217253)
- Myoclonus (HP:0001336): Very brief, involuntary random muscular contractions occurring at rest, in response to sensory stimuli, or accompanying voluntary movements. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:217253)
- Rigidity (HP:0002063): Continuous involuntary sustained muscle contraction. When an affected muscle is passively stretched, the degree of resistance remains constant regardless of the rate at which the muscle is stretched. This feature helps to distinguish rigidity from muscle spasticity. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:217253)
- Chorea (HP:0002072): Chorea (Greek for 'dance') refers to widespread arrhythmic involuntary movements of a forcible, jerky and restless fashion. It is a random-appearing sequence of one or more discrete involuntary movements or movement fragments. Movements appear random because of variability in timing, duration or location. Each movement may have a distinct start and end. However, movements may be strung together and thus may appear to flow randomly from one muscle group to another. Chorea can involve the trunk, neck, face, tongue, and extremities. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:217253)
- Status epilepticus (HP:0002133): Status epilepticus is a type of prolonged seizure resulting either from the failure of the mechanisms responsible for seizure termination or from the initiation of mechanisms which lead to abnormally prolonged seizures (after time point t1). It is a condition that can have long-term consequences (after time point t2), including neuronal death, neuronal injury, and alteration of neuronal networks, depending on the type and duration of seizures. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:217253)
- 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: TAS. Frequency: Occasional (HP:0040283). (ORPHA:217253)
- Generalized-onset seizure (HP:0002197): A generalized-onset seizure is a type of seizure originating at some point within, and rapidly engaging, bilaterally distributed networks. The networks may include cortical and subcortical structures but not necessarily the entire cortex. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:217253)
- Mutism (HP:0002300): Complete lack of speech or verbal communication in a person despite attempts to engage in conversation. Mutism as a phenomena assumes the individual has previous capacity for speech and in the pediatric population it assumes that the person is past the age of typical language development. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:217253)
- Orofacial dyskinesia (HP:0002310). Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:217253)
- Loss of speech (HP:0002371). Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:217253)
- Language impairment (HP:0002463): Language impairment is a deficit in comprehension or production of language that includes reduced vocabulary, limited sentence structure, or impairments in written or spoken communication. Language abilities are substantially and quantifiably below age expectations. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:217253)
- Excessive salivation (HP:0003781): Excessive production of saliva. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:217253)
- Focal-onset seizure (HP:0007359): A focal-onset seizure is a type of seizure originating within networks limited to one hemisphere. They may be discretely localized or more widely distributed, and may originate in subcortical structures. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:217253)
- No social interaction (HP:0008763): Lack of intentional participation in interactions with another person. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:217253)
- 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: TAS. Frequency: Occasional (HP:0040283). (ORPHA:217253)
- Orthostatic tachycardia (HP:0012173): An increase in heart rate with standing of 30 beats per minute or more. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:217253)
- Abnormal sudomotor regulation (HP:0012333): An abnormal regulation of the sweat glands by the sympathetic nervous system associated with abnormal perspiration. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:217253)
- Delirium (HP:0031258): A state of sudden and severe confusion. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:217253)
- Amplification of sexual behavior (HP:5200321): An abnormal increase of libido (sexual desire), typically accompanied by a higher frequency of sexual activity compared to from a person's previous norm. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:217253)
- Neuroblastoma (HP:0003006): Neuroblastoma is a solid tumor that originate in neural crest cells of the sympathetic nervous system. Most neuroblastomas originate in the abdomen, and most abdominal neuroblastomas originate in the adrenal gland. Neuroblastomas can also originate in the thorax, usually in the posterior mediastinum. Evidence: TAS. Frequency: Very rare (HP:0040284). (ORPHA:217253)
- Hodgkin lymphoma (HP:0012189): A type of lymphoma characterized microscopically by multinucleated Reed-Sternberg cells. Evidence: TAS. Frequency: Very rare (HP:0040284). (ORPHA:217253)
- Neoplasm of the breast (HP:0100013): A tumor (abnormal growth of tissue) of the breast. Evidence: TAS. Frequency: Very rare (HP:0040284). (ORPHA:217253)
- Neoplasm of the thymus (HP:0100521): A tumor (abnormal growth of tissue) of the thymus. Evidence: TAS. Frequency: Very rare (HP:0040284). (ORPHA:217253)
- Neoplasm of the lung (HP:0100526): Tumor of the lung. Evidence: TAS. Frequency: Very rare (HP:0040284). (ORPHA:217253)
- Testicular teratoma (HP:0100616): The presence of a teratoma of the testis. Evidence: TAS. Frequency: Very rare (HP:0040284). (ORPHA:217253)
These phenotypes are associated with the disease NMDA receptor encephalitis (ORPHA:217253).