Rare diseases · Sign or symptom
Pes planus
Flat feet
HP:0001763
What it means
A foot where the longitudinal arch of the foot is in contact with the ground or floor when the individual is standing; or, in a patient lying supine, a foot where the arch is in contact with the surface of a flat board pressed against the sole of the foot by the examiner with a pressure similar to that expected from weight bearing; or, the height of the arch is reduced.
Rare diseases that can present with this134
Very common80–99%
20- 48,XYYY syndrome
- Aneurysm-osteoarthritis syndrome
- Atypical Werner syndrome
- B4GALT7-related spondylodysplastic Ehlers-Danlos syndrome
- Classical-like Ehlers-Danlos syndrome type 2
- Dysplasia epiphysealis hemimelica
- Fragile X syndrome
- Kyphoscoliotic Ehlers-Danlos syndrome due to FKBP22 deficiency
- Lipodystrophy due to peptidic growth factors deficiency
- Loeys-Dietz syndrome
- Marfan syndrome
- Pierpont syndrome
- Pitt-Hopkins syndrome
- RIN2 syndrome
- Schwartz-Jampel syndrome
- Shprintzen-Goldberg syndrome
- Spondyloepimetaphyseal dysplasia, Irapa type
- Wilson-Turner syndrome
- Wrinkly skin syndrome
- W syndrome
Common30–79%
41- 47,XYY syndrome
- 48,XXXY syndrome
- 48,XXYY syndrome
- 49,XXXXY syndrome
- Allan-Herndon-Dudley syndrome
- Alström syndrome
- Autosomal recessive axonal Charcot-Marie-Tooth disease due to copper metabolism defect
- Autosomal recessive cerebellar ataxia-pyramidal signs-nystagmus-oculomotor apraxia syndrome
- Autosomal recessive cerebelloparenchymal disorder type 3
- Autosomal recessive cutis laxa type 2A
- Cardiac-valvular Ehlers-Danlos syndrome
- Central core disease
- Classical-like Ehlers-Danlos syndrome type 1
- Coffin-Lowry syndrome
- Congenital myasthenic syndrome with glycosylation defect
- Congenital vertical talus
- Craniofacial dysplasia-short stature-ectodermal anomalies-intellectual disability syndrome
- Craniolenticulosutural dysplasia
- Distal 22q11.2 microdeletion syndrome
- DPM3-CDG
- FG syndrome type 1
- Haim-Munk syndrome
- Hypermobile Ehlers-Danlos syndrome
- Infantile-onset autosomal recessive nonprogressive cerebellar ataxia
- Intellectual disability-muscle weakness-short stature-facial dysmorphism syndrome
- Jacobsen syndrome
- Macrocephaly-intellectual disability-left ventricular non compaction syndrome
- Microduplication Xp11.22p11.23 syndrome
- Monosomy 18q syndrome
- Mowat-Wilson syndrome
- Nail-patella syndrome
- PMM2-CDG
- Progressive spondyloepimetaphyseal dysplasia-short stature-short fourth metatarsals-intellectual disability syndrome
- Smith-Magenis syndrome
- Spondylodysplastic Ehlers-Danlos syndrome
- Spondylo-ocular syndrome
- Temtamy syndrome
- Townes-Brocks syndrome
- Williams syndrome
- X-linked intellectual disability-craniofacioskeletal syndrome
- XYLT1-CDG
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: Dropped arches · Fallen arches · Flat foot
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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.