Rare diseases · Sign or symptom
Atypical behavior
Behavioral abnormality
HP:0000708
What it means
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.
Atypical behaviors should include or directly affect observable actions. While behavioral disorders often encompass abnormal thoughts, feelings, perceptions, or other cognitions, these alone would not be considered atypical behavioral features.
Rare diseases that can present with this293
Very common80–99%
57- 2q23.1microduplication syndrome
- 48,XYYY syndrome
- 49,XXXYY syndrome
- 49,XYYYY syndrome
- 9p13microdeletion syndrome
- ABeta amyloidosis, Arctic type
- ABeta amyloidosis, Dutch type
- ABeta amyloidosis, Iowa type
- Angelman syndrome
- Argininemia
- Autosomal dominant hypocalcemia
- Behavioral variant of frontotemporal dementia
- Carnitine palmitoyl transferase 1A deficiency
- Childhood-onset motor and cognitive regression syndrome with extrapyramidal movement disorder
- Cockayne syndrome
- Delayed encephalopathy due to carbon monoxide poisoning
- Developmental delay-language impairment-dopa responsive dystonia-parkinsonism syndrome due to 2q24 microdeletion
- Diencephalic syndrome
- Epiphyseal dysplasia-hearing loss-dysmorphism syndrome
- Facial dysmorphism-developmental delay-behavioral abnormalities syndrome due to 10p11.21p12.31 microdeletion
- Facial dysmorphism-developmental delay-behavioral abnormalities syndrome due to WAC point mutation
- Familial Alzheimer-like prion disease
- Fetal alcohol syndrome
- Global developmental delay-osteopenia-ectodermal defect syndrome
- Growth delay due to insulin-like growth factor type 1 deficiency
- Homocystinuria due to methylene tetrahydrofolate reductase deficiency
- HSD10 disease, atypical type
- Hyperprolinemia type 2
- Hypohidrotic ectodermal dysplasia-hypothyroidism-ciliary dyskinesia syndrome
- Intellectual disability syndrome due to a DYRK1A point mutation
- Krabbe disease
- Lesch-Nyhan syndrome
- Lissencephaly type 1 due to doublecortin gene mutation
- Locked-in syndrome
- Lujan-Fryns syndrome
- Male hypergonadotropic hypogonadism-intellectual disability-skeletal anomalies syndrome
- Methylmalonic acidemia with homocystinuria, type cblD
- Mitochondrial DNA depletion syndrome, encephalomyopathic form with methylmalonic aciduria
- Mitochondrial membrane protein-associated neurodegeneration
- Monoamine oxidase A deficiency
- Morgagni-Stewart-Morel syndrome
- Mucolipidosis type IV
- Nasu-Hakola disease
- Niemann-Pick disease type C
- NMDA receptor encephalitis
- Pelizaeus-Merzbacher disease
- PFAPA syndrome
- Proximal 16p11.2 microdeletion syndrome
- Rabies
- Sneddon syndrome
- Subacute sclerosing leukoencephalitis
- Tuberous sclerosis complex
- WAC-related facial dysmorphism-developmental delay-behavioral abnormalities syndrome
- X-linked adrenoleukodystrophy
- X-linked alpha-thalassemia-intellectual disability syndrome
- X-linked intellectual disability-hypogonadism-ichthyosis-obesity-short stature syndrome
- Xq12-q13.3 duplication syndrome
Common30–79%
23- 11p15.4microduplication syndrome
- 15q11.2microdeletion syndrome
- 15q24microdeletion syndrome
- 17q11microdeletion syndrome
- 17q24.2microdeletion syndrome
- 1p21.3microdeletion syndrome
- 1p36deletion syndrome
- 1q41q42microdeletion syndrome
- 20q11.2microdeletion syndrome
- 21q22.11q22.12microdeletion syndrome
- 2q37microdeletion syndrome
- 47,XYY syndrome
- 5q35microduplication syndrome
- 8p23.1microdeletion syndrome
- 9q33.3q34.11microdeletion syndrome
- ABetaL34V amyloidosis
- Acute disseminated encephalomyelitis
- Adult polyglucosan body disease
- Alobar holoprosencephaly
- Alpha-mannosidosis
- Alternating hemiplegia of childhood
- Amoebiasis due to free-living amoebae
- Amyotrophic lateral sclerosis
The range is how often this sign appears among people diagnosed with each disease — it is not a probability of having any of them. Many of these signs also occur in common, non-rare conditions. A sign on this page is a conversation to have with a clinician, not a conclusion.
Part of the broader category
Also called: Behavioral changes · Behavioral disorders · Behavioral disturbances · Behavioral problems · Behavioral symptoms · Behavioral/psychiatric abnormalities · Behavioural abnormality · Behavioural changes
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Start free with EleplanThis page uses the Human Phenotype Ontology (2026-06-23) — Human Phenotype Ontology Consortium, hpo.jax.org. Disease associations from Orphanet (INSERM), CC BY 4.0. Content is educational and is not medical advice.