Rare diseases · Sign or symptom
Postaxial hand polydactyly
Extra little finger
HP:0001162
What it means
Supernumerary digits located at the ulnar side of the hand (that is, on the side with the fifth finger).
Rare diseases that can present with this50
Very common80–99%
21- Acrocallosal syndrome
- Acrofacial dysostosis, Weyers type
- Brain malformation-congenital heart disease-postaxial polydactyly syndrome
- Cortical blindness-intellectual disability-polydactyly syndrome
- Crossed polysyndactyly
- Dandy-Walker malformation-postaxial polydactyly syndrome
- Ectrodactyly-polydactyly syndrome
- Greig cephalopolysyndactyly syndrome
- Holoprosencephaly-postaxial polydactyly syndrome
- Hydrolethalus
- Intellectual disability-polydactyly-uncombable hair syndrome
- Meckel syndrome
- Megalencephaly-polymicrogyria-postaxial polydactyly-hydrocephalus syndrome
- Müllerian derivatives-lymphangiectasia-polydactyly syndrome
- Oliver syndrome
- Orofaciodigital syndrome type 4
- Orofaciodigital syndrome type 5
- Polydactyly-myopia syndrome
- Postaxial polydactyly-dental and vertebral anomalies syndrome
- Simpson-Golabi-Behmel syndrome
- Trisomy 13 syndrome
Common30–79%
18- Acalvaria
- Acromesomelic dysplasia, Grebe type
- BRESEK syndrome
- Carpenter syndrome
- Cerebrooculonasal syndrome
- Distal deletion 3p syndrome
- Hirschsprung disease-deafness-polydactyly syndrome
- Lathosterolosis
- McKusick-Kaufman syndrome
- Microcephaly-seizures-intellectual disability-heart disease syndrome
- Microphthalmia with limb anomalies
- Multinodular goiter-cystic kidney-polydactyly syndrome
- Non-distal duplication 13q syndrome
- Orofaciodigital syndrome type 14
- Pallister-Hall syndrome
- PLAA-associated neurodevelopmental disorder
- Short rib-polydactyly syndrome, Verma-Naumoff type
- Smith-Lemli-Opitz 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: Extra pinkie finger · Extra pinky finger · Polydactyly affecting the 5th finger · Postaxial polydactyly of fingers · Postaxial polydactyly of hand · Postaxial polydactyly of hands
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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.