Rare diseases · Sign or symptom
Narrow mouth
Small mouth
HP:0000160
What it means
Distance between the commissures of the mouth more than 2 SD below the mean. Alternatively, an apparently decreased width of the oral aperture (subjective).
The width of the mouth varies with facial movement and must be assessed when the subject has a relaxed (neutral) face. This term replaces microstomia, small oral aperture, and small mouth because the reduced opening of the mouth is secondary to reduced width.
Rare diseases that can present with this150
Very common80–99%
41- 17p13.3microduplication syndrome
- 2p15p16.1microdeletion syndrome
- Agnathia-holoprosencephaly-situs inversus syndrome
- Aortic arch anomaly-facial dysmorphism-intellectual disability syndrome
- AREDYLD syndrome
- Arthrogryposis multiplex congenita-whistling face syndrome
- Camptodactyly-joint contractures-facial skeletal defects syndrome
- Cataract-growth hormone deficiency-sensory neuropathy-sensorineural hearing loss-skeletal dysplasia syndrome
- Charlie M syndrome
- Congenital heart defect-round face-developmental delay syndrome
- Craniofacial-deafness-hand syndrome
- De Barsy syndrome
- Distal 16p11.2 microdeletion syndrome
- Distal deletion 17q syndrome
- Distal duplication 6p syndrome
- Ear-patella-short stature syndrome
- Fetal valproate spectrum disorder
- Flat face-microstomia-ear anomaly syndrome
- Freeman-Sheldon syndrome
- Hamel cerebro-palato-cardiac syndrome
- Harrod syndrome
- Hutchinson-Gilford progeria syndrome
- Hypoglossia-hypodactyly syndrome
- Isolated rhombencephalosynapsis
- Lethal faciocardiomelic dysplasia
- Lipodystrophy due to peptidic growth factors deficiency
- Mandibuloacral dysplasia with type B lipodystrophy
- Marden-Walker syndrome
- Microcephaly-microcornea syndrome, Seemanova type
- Monosomy 9q22.3 syndrome
- Musculocontractural Ehlers-Danlos syndrome
- Myhre syndrome
- Oral submucous fibrosis
- Otopalatodigital syndrome type 2
- Restrictive dermopathy
- Ring chromosome 7 syndrome
- Ruvalcaba syndrome
- Schwartz-Jampel syndrome
- Thakker-Donnai syndrome
- Wiedemann-Rautenstrauch syndrome
- XK aprosencephaly syndrome
Common30–79%
38- 14q11.2microdeletion syndrome
- 19p13.3microduplication syndrome
- 1p36deletion syndrome
- 20p12.3microdeletion syndrome
- 5q22microdeletion syndrome
- 8q12microduplication syndrome
- 9q33.3q34.11microdeletion syndrome
- Acromicric dysplasia
- Aphonia-deafness-retinal dystrophy-bifid halluces-intellectual disability syndrome
- Auriculocondylar syndrome
- Autism spectrum disorder due to AUTS2 deficiency
- Aymé-Gripp syndrome
- B4GALT7-related spondylodysplastic Ehlers-Danlos syndrome
- Baller-Gerold syndrome
- Bartsocas-Papas syndrome
- Camptodactyly syndrome, Guadalajara type 1
- CHARGE syndrome
- Desmosterolosis
- Dislocation of the hip-dysmorphism syndrome
- Distal duplication 5q syndrome
- Distal limb deficiencies-micrognathia syndrome
- Double outlet right ventricle
- Down syndrome
- Fibrochondrogenesis
- Hajdu-Cheney syndrome
- Hallermann-Streiff syndrome
- Hereditary acrokeratotic poikiloderma
- Hypomandibular faciocranial dysostosis
- Iniencephaly
- Intellectual disability-muscle weakness-short stature-facial dysmorphism syndrome
- Lethal hemolytic anemia-genital anomalies syndrome
- Marfanoid habitus-autosomal recessive intellectual disability syndrome
- Megalencephaly-polymicrogyria-postaxial polydactyly-hydrocephalus syndrome
- Monosomy 9p syndrome
- Multiple pterygium-malignant hyperthermia syndrome
- Oculoauriculofrontonasal syndrome
- Oculocerebral hypopigmentation syndrome, Cross type
- Systemic 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, and Orphanet separately records 1 disease where this sign is specifically absent. A sign on this page is a conversation to have with a clinician, not a conclusion.
Part of the broader category
Also called: Microstomia · Small oral aperture
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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.