Rare diseases · Sign or symptom
Mandibular prognathia
Big lower jaw
HP:0000303
What it means
Abnormal prominence of the chin related to increased length of the mandible.
Rare diseases that can present with this136
Very common80–99%
31- 49,XXXYY syndrome
- Achalasia-microcephaly syndrome
- Acromegaly
- Aminopterin/methotrexate embryofetopathy
- AREDYLD syndrome
- Aspartylglucosaminuria
- Autosomal dominant prognathism
- Blepharophimosis-ptosis-esotropia-syndactyly-short stature syndrome
- Branchioskeletogenital syndrome
- Familial osteodysplasia, Anderson type
- Hydrocephalus-costovertebral dysplasia-Sprengel anomaly syndrome
- Hyperostosis corticalis generalisata
- Intellectual disability, Buenos-Aires type
- Intellectual disability-dysmorphism-hypogonadism-diabetes mellitus syndrome
- Intellectual disability-polydactyly-uncombable hair syndrome
- Lenz-Majewski hyperostotic dysplasia
- Microbrachycephaly-ptosis-cleft lip syndrome
- MMEP syndrome
- Myhre syndrome
- Nance-Horan syndrome
- Pituitary gigantism
- Progeroid syndrome, Petty type
- Radial hypoplasia-triphalangeal thumbs-hypospadias-maxillary diastema syndrome
- Rhizomelic dysplasia, Patterson-Lowry type
- Simpson-Golabi-Behmel syndrome
- Skeletal dysplasia-epilepsy-short stature syndrome
- Somatomammotropinoma
- Spondyloepimetaphyseal dysplasia, aggrecan type
- Waardenburg syndrome type 1
- X-linked intellectual disability-hypogammaglobulinemia-progressive neurological deterioration syndrome
- Xp22.13p22.2duplication syndrome
Common30–79%
48- 5q22microdeletion syndrome
- 9q31.1q31.3microdeletion syndrome
- Acrodysostosis
- Anophthalmia-megalocornea-cardiopathy-skeletal anomalies syndrome
- Apert syndrome
- Autosomal dominant hyper-IgE syndrome due to STAT3 deficiency
- Basel-Vanagaite-Smirin-Yosef syndrome
- Beckwith-Wiedemann syndrome
- Camptodactyly syndrome, Guadalajara type 1
- Cleidocranial dysplasia
- Cockayne syndrome type 1
- Cockayne syndrome type 2
- Congenital infiltrating lipomatosis of the face
- Dermoodontodysplasia
- Epidermolysis bullosa simplex with anodontia/hypodontia
- Facial dysmorphism-shawl scrotum-joint laxity syndrome
- FOXG1 syndrome due to 14q12 microdeletion
- FOXP1 Syndrome
- Fragile X syndrome
- Frank-Ter Haar syndrome
- GAPO syndrome
- GM1 gangliosidosis
- Intellectual disability-obesity-prognathism-eye and skin anomalies syndrome
- Isolated ectopia lentis
- Jackson-Weiss syndrome
- Kleefstra syndrome
- McDonough syndrome
- Megalencephaly-severe kyphoscoliosis-overgrowth syndrome
- Microcephaly-facial dysmorphism-ocular anomalies-multiple congenital anomalies syndrome
- Microcephaly-glomerulonephritis-marfanoid habitus syndrome
- Monosomy 18q syndrome
- Mowat-Wilson syndrome
- Mowat-Wilson syndrome due to a ZEB2 point mutation
- Mowat-Wilson syndrome due to monosomy 2q22
- Neurofaciodigitorenal syndrome
- Oculodentodigital dysplasia
- Oliver syndrome
- PDE4D haploinsufficiency syndrome
- Phenobarbital embryopathy
- PMM2-CDG
- Postaxial polydactyly-dental and vertebral anomalies syndrome
- Progressive essential tremor-speech impairment-facial dysmorphism-intellectual disability-abnormal behavior syndrome
- Proteus-like syndrome
- Pyle disease
- Renpenning syndrome
- Severe intellectual disability-epilepsy-anal anomalies-distal phalangeal hypoplasia
- Severe microbrachycephaly-intellectual disability-athetoid cerebral palsy syndrome
- Severe oculo-renal-cerebellar syndrome
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: Big mandible · Enlarged mandible · Enlargement of mandible · Hyperplasia of lower jaw · Hypertrophy of lower jaw · Hypertrophy of mandible · Increased projection of lower jaw · Increased projection of mandible
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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.