Contents
What is polydactyly
Polydactyly is a condition in which a person has more than 5 fingers per hand or 5 toes per foot. Polydactyly is the most common birth defect of the hand and foot. Polydactyly can occur as an isolated finding such that the person has no other physical anomalies or intellectual impairment. However, polydactyly can occur in association with other birth defects and cognitive abnormalities as part of a genetic syndrome.
Polydactyly can be broadly classified as 1:
- Pre-axial polydactyly: extra digit(s) towards the thumb/hallux (radially) – extra first digit
- Post-axial polydactyly: extra digit(s) towards little finger/toe (ulnar) – extra fifth digit
- Central polydactyly: central polydactyly involves duplication of the second, third, or fourth digit.
Estimated incidence is different for pre and post-axial polydactyly 2:
- Post-axial polydactyly: ~1 in 3000
- Pre-axial polydactyly: ~1 in 7000
- Central polydactyly is the rarest encountered.
The association of hand and foot polydactyly is uncommon. If hand and foot polydactyly does occur, it may be a case of “crossed polydactyly”—when preaxial involement of the hand and postaxial involvement of the foot occurs or vice versa.
In addition, there may be a greater prevalence in individuals of African descent (particularly for post-axial polydactyly) 3.
Polydactyly or having extra fingers or toes (6 or more) can occur on its own. There may not be any other symptoms or disease present. Polydactyly may be passed down in families. This trait involves only one gene that can cause several variations.
African Americans, more than other ethnic groups, can inherit a 6th finger. In most cases, this is not caused by a genetic disease.
Polydactyly can also occur with some genetic diseases. If polydactyly is an isolated anomaly it is incidental and not of concern but if polydactyly is associated with another anomaly it then carries a vastly variable prognosis dependent on the rest of the syndrome.
Extra digits may be poorly developed and attached by a small stalk. This most often occurs on the little finger side of the hand. Poorly formed digits are usually removed. Simply tying a tight string around the stalk can cause it to fall off in time if there are no bones in the digit.
In some cases, the extra digits may be well-formed and can even function.
In some cases, the extra digits may be well-formed and functional. Surgery may be considered especially for poorly formed digits or very large extra digits. Surgical management depends greatly on the complexity of the deformity 4. Larger digits may need surgery to be removed.
Figure 1. Polydactyly
Footnote: A 39-year-old man presented for evaluation of his acne. He had no notable medical history and was taking no medications. Physical examination revealed an incidental finding of six functional digits on his hands and feet. He had no family history of similar findings. Bilateral polydactyly of the hands and feet is rare. The extra digit can be postaxial (occurring along the ulnar aspect of the hand or fibular aspect of the foot), preaxial (occurring along the radial aspect of the hand or tibial aspect of the foot), or central (occurring in the middle of the hand or foot). Polydactyly can occur by itself, typically as a manifestation of autosomal dominant mutations, or in conjunction with a syndrome of congenital anomalies. This patient did not have any additional congenital anomalies associated with the bilateral postaxial polydactyly. No treatment is required for the condition, but surgical removal for cosmesis and comfort is feasible.
[Source 5 ]Preaxial polydactyly
Pre-axial polydactyly refers to polydactyly where the additional digit is towards the first digit of the hand (radial side) or foot (medially).
Pre-axial polydactyly is less common than post-axial polydactyly, with an estimated incidence of 1 in 7000.
Pre-axial polydactyly associations
Pre-axial polydactyly can be associated with:
- Down syndrome
- VATER association
- Holt-Oram syndrome
- Greig cephalopolysyndactyly syndrome
- Carpenter syndrome
- Laurin-Sandrow syndrome
- Fanconi anemia
Post-axial polydactyly
Post-axial polydactyly refers to polydactyly where the additional digit is on the ulnar margin of the hand, or lateral to the 5th toe.
Post-axial polydactyly is more common than pre-axial polydactyly, with an estimated incidence of 1 in 3000.
Postaxial hand polydactyly is a common isolated disorder in black children and autosomal dominant transmission is suspected 4. In contrast, postaxial polydactyly seen in white children is usually syndromic and associated with an autosomal recessive transmission. Postaxial polydactyly is approximately 10 times more frequent in blacks than in whites and is more frequent in male children 4.
Other factors associated with postaxial hand polydactyly include twinning, low maternal education, parental consanguinity, occurrence in first-degree relatives, and maternal bleeding in the first trimester 4.
Post-axial polydactyly has been defined by Temtamy and McKusick as 1:
- Type A: additional digit at the metacarpophalangeal joint (or more proximally at the carpometacarpal joint)
- Type B: small nubbin of non-functioning tissue or additional soft tissue on a pedicle
Or, you can use a separate three-part classification system:
- Type 1: nubbin or floating digit
- Type 2: duplications at the metacarpophalangeal joint
- Type 3: duplication of the entire ray
Post-axial polydactyly associations
Post-axial polydactyly can be associated with:
- Patau syndrome (trisomy 13)
- Bardet-Biedl syndrome
- Meckel Gruber syndrome
- McKusick-Kaufman syndrome
- Following oral-facial-digital syndromes (OFDS)
- Oral-facial-digital syndrome (OFDS) type 2 – Mohr syndrome
- Oral-facial-digital syndrome (OFDS) type 6
- Certain skeletal dysplasias
- Chondroectodermal dysplasia – Ellis-van Creveld syndrome
- Asphyxiating thoracic dysplasia – Jeune syndrome
- Smith Lemli Opitz syndrome
- Certain short rib polydactyly syndromes: e.g types 1 and 3
Polydactyly causes
Polydactyly is the most common congenital digital anomaly of the hand and foot. Polydactyly may appear in isolation or in association with other birth defects. Isolated polydactyly is often autosomal dominant, while syndromic polydactyly is often autosomal recessive 6.
Current theories on polydactyly focus on mutations in specific genetic locations that cause limb development to go awry 7.
Many specific mutations have been linked to polydactyly; however, a molecular etiology has not been found in a third of human disorders associated with polydactyly 8.
Mammals have been shown to have genetic clusters identified as homeobox or Hox genes corresponding to five domains across the limb bud. According to Muragaki et al 9, mutations in the HOXD13 gene are associated with synpolydactyly.
The steps in limb development and outgrowth are controlled by at least two described signal centers, as follows 8:
- Zone of polarizing activity (ZPA) – Sonic Hedgehog is a molecule found to mediate ZPA activity
- Apical ectodermal ridge (AER) – Expresses fibroblast growth factors
As limb growth in utero progresses along a preset timeline, elongation of the limb, development of soft tissue, and differentiation of digits progresses.
Polydactyly causes may include:
- Asphyxiating thoracic dystrophy
- Carpenter syndrome
- Ellis-van Creveld syndrome (chondroectodermal dysplasia)
- Familial polydactyly
- Laurence-Moon-Biedl syndrome
- Rubinstein-Taybi syndrome
- Smith-Lemli-Opitz syndrome
- Trisomy 13 (Patau syndrome)
Polydactyly genetics
A large proportion of polydactyly is isolated although they can be associated with an immense amount of anomalies which include:
- Aneupliodic syndromic
- Trisomy 13 (Patau syndrome): tends to give post-axial polydactyly
- Non-aneuploidic syndromic
- Bardet-Biedl syndrome: often post-axial
- Carpenter syndrome
- Fetal valproate syndrome
- Hydrolethalus syndrome
- Joubert syndrome
- Juberg-Hayward syndrome
- Lhermitte duclos disease
- Meckel Gruber syndrome: tends to be post-axial
- McKusick-Kaufman syndrome: post-axial 10
- Megalencephaly, polymicrogyria, polydactyly, and hydrocephalus (MPPH) syndrome 11
- Oral-facial-digital syndromes
- Oral-facial-digital syndrome (OFDS) type 2 – Mohr syndrome: post-axial
- Oral-facial-digital syndrome (OFDS) type 6: post-axial 12
- Pallister-Hall syndrome
- Short rib polydactyly syndrome(s) 13
- Skeletal dysplasias
- Smith-Lemli-Opitz syndrome
- VACTERL association
- Non-aneuploidic, non-syndromic
- Macrodystrophia lipomatosa
- Syndactyly: most common associated limb anomaly, it is then termed polysyndactyly
Table 1. Clinical Entities That Manifest Polydactyly (abbreviations: D = Autosomal dominant inheritance, R = Autosomal recessive inheritance, X = Sex-linked Inheritance, M = Multiple modes of inheritance, U = Unknown inheritance. Highlighted clinical entities are non-syndromic.)
| Inheritance | Clinical Entity | Gene |
| D | Aase Smith Syndrome Type I | |
| R | Achondrogenesis, Type II | COL2A1 |
| R | Acro-Cranio-Facial Dysostosis | |
| R | Acrocallosal Syndrome | GLI3 |
| R | Acrocephalopolysyndactylous Dysplasia | |
| R | Acrocephalosyndactyly Type I | |
| U | Acrofacial Dysostosis | |
| R | Acrofacial Dysostosis-Type Rodriguez | |
| R | Acrofrontofacionasal Dysostosis Type 1 | |
| R | Acrofrontofacionasal Dysostosis Type 2 | |
| D | Acromelic Frontonasal Dysostosis | |
| D | Acropectoral Syndrome | |
| D | Acropectorovertebral Dysplasia, F-form of | |
| U | Acrorenal | |
| R | Acrorenal-Mandibular Syndrome | |
| U | Adamsbaum (1991) Syndrome | |
| U | Aminopterin Syndrome sine Aminopterin | |
| U | Anandan (2008) Sternal Defects – Aplasia Cutis Congenita-Polydactyly | |
| D | Apert Syndrome | FGFR2 |
| U | Arens (1991) Acrofacial Dysostosis | |
| R | Arimia Syndrome | |
| R | Asphyxiating Thoracic Dystrophy | IFT80, DYNC2H1 |
| D | Atelosteogenesis Type III | FLNB |
| U | Baisch-Polydactyly; Absent Nails | |
| R | Baller-Gerold Syndrome | RECQL4 |
| U | Baraitser-Brachyphalangy-Polydactyly-Absent Tibiae | |
| U | Barakat (1996) Polydactyly-Osteopenia-Hypoplastic Kidney | |
| R | Bardet-Biedl Syndrome | BBS1, BBS2, ARL6, BBS4, BBS5, MKKS, BBS7, TTC8, BBS9, BBS10, BBS11, BBS12 |
| D | Basal Cell Nevus Syndrome | PTCH1 |
| U | Bates (2002) Acrofacial Dysostosis-Digital Anomalies-Renal Agenesis | |
| D | Beckwith-Wiedemann Syndrome | CDKN1C |
| R | Biemond Syndrome II | |
| U | Bitoun (1994)-Glaucoma-Thumb Anomalies-Joint Dislocations | |
| R | Blair (2000) Autosomal Recessive Craniosynostosis Syndrome | |
| R | Bloom Syndrome | RECQL3 |
| R | Bonneau Syndrome | |
| D | Brachydactyly (Preaxial) Hallux Varus-Thumb Abduction | |
| D | Brachydactyly Type B | ROR2 |
| D | Brachydactyly Type C | GDF5 |
| D | Brachyphalangy, Polydactyly, and Tibial Aplasia/Hypoplasia | |
| U | Braddock (2003) Laryngeal Webs; CHD; Vertebral Defects | |
| D | Branchiooculofacial Syndrome | TFAP2A |
| R | Braun (1962) Nephrosis; Deafness; Brachytelephalangy | |
| X | BRESHECK | |
| U | Brunoni (1984) Radial Aplasia; Short Stature; Unusual Face | |
| D | C Syndrome | CD96 |
| D | C-LIKE Syndrome | CD96 |
| R | Camptobrachydactyly | |
| R | Carpenter Syndrome | RAB23 |
| U | Carpenter-Hunter-Micromelia; Polysyndactyly; Encephalocele; Fragile Bones | |
| U | Cerebro-fronto-facial Syndrome Type III | |
| R | Cerebrofaciothoracic Dysplasia | |
| D | Cerebrooculonasal Syndrome | |
| D | CHAR Syndrome | TFAP2B |
| D | CHARGE Syndrome | CHD7, SEMA3E |
| U | Chitayat (1993) Hyperphalangism; Hallux Valgus; Bronchomalacia | |
| R | Chitty (1993) Bowed Tibiae; Radial Anomalies; Osteopenia; Fractures | |
| U | Chondrodysplasia-Situs Inversus-Cystic Pancreatic Dysplasia | |
| R | Chondrodysplasia, Grebe Type | GDF5 |
| X | Chonrdodysplasia Punctata 2, X-Linked Dominant | EBP |
| R | Cleft Lip/Palate with Characteristic Facies, Intestinal Malrotation, and Lethal Congenital Heart Disease | |
| U | COH Syndrome-Craniosynostosis; Bifid Thumb; Micropenis | |
| D | Colobomas-Brachydactyly (Type Sorsby) | |
| U | Craniofacial Malformations, Asymmetric, with Polysyndactyly and Abnormal Skin and Gut Development | |
| X | Craniofrontonasal Syndrome | EFNB1 |
| D | Culler (1984) Hypopituitarism; Postaxial Polydactyly | |
| U | Cutis Aplasia-Blue Sclerae-Hypertelorism-Polydactyly-Hypoplastic Nipples | |
| U | Cutis Marmorata Telangiectasia Congenita | |
| R | Dandy-Walker Malformation with Postaxial Polydactyly | |
| D | De Smet Complex Synpolydactyly | FBLN1 |
| D | Deafness, Congenital and Onychodystrophy, Autosomal Dominant | |
| U | Deafness, Onychodystrophy, Triphalangeal Thumbs | |
| R | Desbuquois (1966)-Chondrodystrophy; Advanced Bone Age | CANT1 |
| R | Diamond-Blackfan | RPS19, RPL5, RPL11 |
| U | Disorganization, Mouse, Homolog of | |
| U | Donnai (1988) Meckel-like Syndrome | |
| R | DOOR | |
| U | Double Nail For Fifth Toe | |
| D | Duane-Radial Ray Syndrome | SALL4 |
| U | Duplication of Lower Limb-Plus | |
| U | Ectodermal Dysplasia Syndrome with Distinctive Facial Appearance and Preaxial Polydactyly of Feet | |
| M | Ectrodactyly-Autosomal Dominant | WNT10A |
| R | Ectrodactyly-Polydactyly | |
| R | Eiken (1984) Retarded Ossification; Abnormal Modeling of Bones | PTHR1 |
| R | Ellis-Van Creveld Syndrome | EVC, EVC2 |
| R | Encephalocele-Radial, Cardiac, Gastrointestinal, Anal/renal Anomalies | |
| R | Endocrine-Cerebrosteodysplasia | ICK |
| R | Engelhard (1979) Pre- and Postaxial Polysyndactyly; Ptosis | |
| R | Faciocardiomelic Syndrome | |
| R | Fanconi Pancytopenia Syndrome | FANCA, FANCB, BANCC, FANCD1, FANCD2, FANCE, FANCF, XRCC9, FANCI, FANCJ, PHF9, FANCM, FANCN, FANCO |
| R | Fibular Aplasia or Hypoplasia, Femoral Bowing and Poly-, Syn-, and Oligodactyly | WNT7A |
| U | Femoral-Facial Syndrome | |
| U | Ferda Percin-Yilmaz-Syn-Poly-Oligo-Brachydactyly | |
| U | Fibular Aplasia-Anonychia-Finger Polydactyly-Toe Oligodactyly | |
| U | Fibular Hemimelia-Polysyndactyly | |
| D | Floating-Harbor-Short Stature-Delayed Bone Age-Broad Nose | |
| U | Focal Dermal Hypoplasia, Morning Glory Anomaly, and Polymicrogyria | |
| X | Focal Dermal Hypoplasia | PORCN |
| U | Franceschini (1994) Mask-Like Face; Ear Anomalies; Digital Malformations | |
| D | Frias Syndrome | |
| M | Frontonasal Dysplasia | ALX3 |
| U | Fryns-Aftimos | |
| U | Fryns-Lagae-Rizzo-Polydactyly-Growth Retardation-Spasticity-Urogenital | |
| U | Gandhi (2008) | |
| U | Garrett-Tripp-MR; Polydactyly; Hair Absence; Dermatitis; Perthe’s Disease | |
| U | Giant Diencephalic Hamartoma-Facial Cleft-Ear and Eye Anomalies | |
| U | Goiter, Multinodular, Cystic Renal Disease, and Digital Anomalies | |
| R | Goossens (2006) Congenital Heart Disease-Polydactyly-Ectopic Neuropituitary | |
| D | Greig Cephalopolysyndactyly Syndrome | GLI3 |
| U | Growth and Mental Retardation, Mandibulofacial Dysostosis, Microcephaly, and Cleft Palate | |
| U | Gül (2000)-Craniofacial Anomalies | |
| R | Guschmann (2001) Mesomelic Campomelia-Polydactyly-Dandy-Walker | |
| R | Hallux Varus and Preaxial Polysyndactyly | |
| U | Hameed (1999) Acrocraniofacial Syndrome | |
| U | Happle-Tinschert Syndrome | |
| U | Hartsfield (1984) Holoprosencephaly; Ectrodactyly; Cleft Face | |
| R | Heart-hand-Type 4-with Mesoaxial Hexadactyly | |
| U | Hemifacial Microsomia-Radial Defects | |
| U | Hemihypertrophy-Hemimegalencephaly-Polydactyly | |
| R | Hernandez (1985) Cortical Blindness; Polydactyly; Mental Retardation | |
| R | Hirschsprung Disease with Heart Defects, Laryngeal Anomalies, and Preaxial Polydactyly | |
| R | Hirschsprung Disease with Polydactyly, Renal Agenesis, and Deafness | |
| R | Hirschsprung Disease with Ulnar Polydactyly, Polysyndactyly of Big Toes, and Ventricular Septal Defect | |
| U | Ho (1975) Cleft Palate; Congenital Heart Disease; Absent Tibia; Polydactyly | |
| U | Holmes-Schimke-Microcephaly; CHD; Skeletal Abnormalities | |
| D | Holprosencephaly 9 | GLI2 |
| D | Holt-Oram Syndrome | TBX5 |
| R | Holzgreve Syndrome | |
| R | Huang (1999) Hirschsprung, Congenital Heart Defect, Laryngeal Anomalies | |
| R | Hydrolethalus Syndrome 1 | HYLS1 |
| R | Hydrops-Ectopic Calcification-Moth-Eaten Skeletal Dysplasia | LBR |
| D | Hypomelia with Müllerian Duct Anomalies | |
| M | Hypoplastic Left Heart-Postaxial Polydactyly | |
| U | Johnson (1974) Glossopalatine Ankylosis; Cataracts; Abnormal Digits | |
| U | Johnson Neuroectodermal Syndrome | |
| M | Joubert Syndrome; JBTS | CXORF5, INPP5E, TMEM216, RPGRIP1L |
| U | Kantaputra (2003) Symphalangism; Multiple Frenula; Polydactyly; Dental Anomalies | |
| D | Klippel-Trenaunay-Weber Syndrome | |
| R | Kondoh (2001) Microcephaly-growth Retardation-Atopic Dermatitis-Mental Retardation | |
| R | Kozlowski-Krajewska-Polydactyly-Brachydactyly-Uncombable Hair-Mental Retardation | |
| D | Lacrimoauriculodentodigital Syndrome | FGFR2, FGFR3, FGF10 |
| R | Lambotte (1990) Microcephaly, Large Ears, Polydactyly, Hypoplastic Thumb | |
| U | Lampert (1984)-Craniostenosis; Polydactyly | |
| U | Landy-Donnai-Split Hand; Hydrops; Renal Anomalies | |
| U | Laryngomalacia-Plus | |
| R | Lathosterolosis | SC5DL |
| D | Laurin-Sandrow Syndrome | |
| X | Lenz Microphthalmia | |
| U | Linear Nevus Sebaceous Syndrome | |
| R | Liver Fibrocystic Disease and Polydactyly | |
| U | Macrocephaly-Capillary Malformation | |
| U | Mandibulofacial Dysostosis-Type Guion-Almeida | |
| U | Mardini (1985) Lung Agenesis; Congenital Heart Disease; Thumb Anomalies | |
| D | Martin-Gorski-Ocular Malformations-polydactyly-membranous Bone Abnormal | |
| D | Martinez-Frias (1995) Distal Aphalangia; Syndactyly; Microcephaly | |
| U | Martsolf (1977) Skeletal Dysplasia; Polydactyly; Pierre Robin | |
| U | McGaughran (1998) Micrognathia-Syndactyly | |
| R | McKusick (1968) Cataract; Unilateral Limb Defects | |
| R | McKusick-Kaufman Syndrome | MKKS |
| R | Meckel Syndrome | CC2D2A, CEP290, MKS1, TMEM67, RPGRIP1L |
| R | Megalencephaly Polymicrogyria-Polydactyly Hydrocephalus Syndrome | |
| R | Megalocornea-Mental Retardation Syndrome | |
| U | Meningocoele-Renal Dysplasia-Postaxial Polydactyly | |
| R | Mental Retardation, Congenital Heart Disease, Blepharophimosis, Blepharoptosis and Hypoplastic Teeth | |
| R | Mental Retardation, Truncal Obesity Retinal Dystrophy, and Micropenis | INPP5E |
| R | Microcephaly with Mental Retardation and Digital Anomalies | |
| U | Microcephaly, Corpus Callosum Dysgenesis, and Cleft Lip/Palate | |
| R | Microphthalmia with Limb Anomalies | |
| D | Microphthalmia, Syndromic 6 | BMP4 |
| R | Mildenberger (1998) Diffuse Mesangial Sclerosis-Dandy-Walker-polydactyly | |
| U | Mirror-Image Polydactyly | MIPOL1 |
| M | Moebius | |
| R | MOHR Syndrome | |
| U | Morava (2004) Focal Skin Defect-Microphthalmia-Limb Defects | |
| R | Morton (1998) Lethal Skeletal Dysplasia-Ectopic Digits | |
| R | Müllerian Derivatives Persistence of, with Lymphangiectasia and Postaxial Polydactyly | |
| R | Multiple Maternal Hypomethylation Syndrome | |
| X | Multiple Pterygium Syndrome, X-Linked | |
| U | MURCS | |
| D | Nager Acrofacial Dysostosis | |
| U | Neural Tube Defect-Preaxial Polydactyly-Vertebral Anomalies | |
| R | Neuro-Facio-Digito-Renal Syndrome | |
| U | NevusComedonicus Syndrome | |
| R | Nijmegen Immunodeficiency Syndrome | NBN |
| U | Occult Toe | |
| D | Oculo-dento-digital Syndrome | GJA1 |
| R | Odontotrichomelic Syndrome | |
| U | OEIS | |
| R | Oliver Syndrome | |
| D | Onychonychia-Acral Defects-Cooks | SOX9 |
| U | Opitz (1989) Mandibulofacial Dysostosis; Hexadactyly; Lymphoedema | |
| U | Oral-Facial-Digital Syndrome-Cerebral Dysgenesis | |
| U | Oral-Facial-Digital Syndrome-Type Gabrielli | |
| U | Oral-Facial-Digital Syndrome-Type Stenram | |
| U | Oral-Facial-Digital Syndrome-Type XII | |
| X | Oral-Facial-Digital Syndrome Syndrome I; OFD1 | CXORF5 |
| R | Oral-Facial-Digital Syndrome Syndrome III; OFD3 | |
| R | Oral-Facial-Digital Syndrome Syndrome IV; OFD4 | |
| R | Oral-Facial-Digital Syndrome Syndrome IX; OFD9 | |
| D | Oral-Facial-Digital Syndrome Syndrome V; OFD5 | |
| R | Oral-Facial-Digital Syndrome Syndrome VI; OFD6 | |
| X | Oral-Facial-Digital Syndrome Syndrome VIII; OFD8 | |
| D | Oral-Facial-Digital Syndrome Syndrome X; OFD10 | |
| R | Orstavik (1992) Oral-Cardiac-Digital Syndrome | |
| U | Osteochondrodysplasia-Osteopenia-Preaxial Polydactyly | |
| X | Otopalatodigital Syndrome, Type II | FLNA |
| D | Pallister-Hall Syndrome; PHS | GLI3 |
| R | Panigrahi (2002) Ptosis Polydactyly Mental Retardation | |
| U | Parentin-Perissutti Single Incisor-Duane-Bifid Thumb | |
| U | Pavone (1991) Connective Tissue Disorder; Polydactyly | |
| U | Percin and Percin (2003) An Unusual Syndactyly | |
| R | Peters’ Anomaly-Microphthalmia-Arhinia | |
| U | Pfeiffer-Angerstein-Bowing-Bone Dysplasia | |
| R | Pfeiffer-Mayer-Coloboma; Polydactyly; Mental Retardation | |
| R | Phadke (1999) Complex Camptopolydactyly | |
| U | Piepkorn (1977) Short Ribs; Polydactyly | |
| U | Polydactyly-Colobomata-Hypopituitarism-Cleft Palate | |
| U | Polydactyly-Palmar Type | |
| U | Polydactyly-Panfollicular Nevus | |
| U | Polydactyly-Renal Vascular Malformation | |
| U | Polydactyly-Obstructive Uropathy | |
| M | Polydactyly, Postaxial | GLI3 |
| U | Polydactyly, Postaxial, with Dental and Vertebral Anomalies | |
| D | Polydactyly, Postaxial, with Progressive Myopia | |
| D | Polydactyly, Preaxial I | |
| D | Polydactyly, Preaxial II; PPD2 | SHH ZRS |
| D | Polydactyly, Preaxial III | |
| D | Polydactyly, Preaxial IV | GLI3 |
| U | Polymetatarsia-Without Polydactyly. | |
| U | Polysyndactyly-Delta Phalanges | |
| R | Polysyndactyly with Cardiac Malformation | |
| D | Polysyndactyly, Crossed | |
| R | Postaxial Acrofacial Dysostosis | DHODH |
| D | Postaxial Oligodactyly, Tetramelic | |
| U | Postaxial Polydactyly-Atrium Anomaly | |
| U | Postaxial Polydactyly-Single Atrium-Mental Retardation | |
| D | Preaxial Deficiency Postaxial Polydactyly, and Hypospadias | HOXA13 |
| R | Pseudotrisomy 13 Syndrome | |
| D | Radial Defects-Deafness (IVIC) | |
| X | Radioulnar Synostosis-Radial Ray Anomalies | |
| R | Reinitis Pgmentosa 41 | PROML1 |
| R | Renal Dysplasia; Limb Defects | |
| R | Renal-Hepatic-Pancreatic Dysplasia | NPHP3 |
| M | Rhombencephalosynapsis | |
| U | Rippberger (1976) BBB-like Syndrome with Brachydactyly | |
| D | Robinow Syndrome | ROR2 |
| D | Robinow-Sorauf Syndrome | TWIST |
| D | Rubinstein-Taybi Syndrome | CBP |
| U | Sakati-Nyhan-Acrocephalopolysyndactyly Type III | |
| U | Say (1987) Clover-leaf Skull; Skeletal Dysplasia | |
| U | Scalp Defects and Postaxial Polydactyly | |
| R | Schinzel-Giedion Midface-Retraction Syndrome | SETBP1 |
| D | Schmitt Hypoplastic Radius, Hypospadias, Maxillary Diastema | |
| R | Sener (1990) Synpolydactyly | |
| U | Shepherd (1989) Noonan-like Syndrome | |
| U | Short Rib-polydactyly Syndrome (Kannu-Aftimos) | |
| R | Short Rib-Polydactyly Syndrome, Type I | |
| R | Short Rib-Polydactyly Syndrome, Type II | |
| R | Short Rib-Polydactyly Syndrome, Type III | DYNC2H1 |
| R | Short Rib-Polydactyly Syndrome, Type IV | |
| X | Siderius X-Linked Mental Retardation Syndrome | PHF8 |
| X | Simpspn-Golabi-Behmel Syndrome, Type I | GPC3 |
| D | Sinha-Verma-Postaxial and Mesoaxial Polydactyly | |
| U | Situs Inversus-Polydactyly-Broad Thumbs | |
| R | Sjogren-Larsson-Like Syndrome with Bone Dysplasia | |
| R | Smith-Lemli-Opitz Syndrome | DHCR7 |
| D | Split-Hand/Foot Malformation | |
| R | Spondylocaroptarsal Synostosis Syndrome | FLNB |
| U | Spondylocostal Dysostosis-Preaxial Polydactyly | |
| R | Spondylocostal Dysostosis | DLL3 |
| U | Stoll-Gasser-Hepatic Ductal Plate Anomalies; Digital Anomalies; Congenital Heart Disease | |
| U | Sugiura-Lenz (1999) Polysyndactyly | |
| U | Sulko (2010) Tibial Hemimelia-Preaxial Polydactyly-Heart Defects | |
| D | Syndactyly-Polydactyly-Earlobe Syndrome | |
| D | Syndactyly, Type IV | SHH ZRS |
| D | Synpolydactyly 1; SPD1 | HOXD13 |
| D | Synpolydactyly 2; SPD2 | FBLN1 |
| D | Tabatznik Syndrome | |
| U | Tarhan (2004) Mental Retardation, Polysyndactyly, Deafness, Facial Dysmorphism | |
| U | Thai Symphalangism Syndrome | |
| D | Thanatophoric Dysplasia, Type I | FGFR3 |
| U | Thumb Hypoplasia-Preaxial Toe Polydactyly | |
| R | Tibia, Absence of Hypoplasia of, with Polydactyly, Retrocerebellar Arachnoid Cyst, and Other Anomalies | |
| U | Tibia, Absence of, with Polydactyly | |
| D | Tibia, Hypoplasia of, with Polydactyly | |
| D | Tibial Aplasia Ectrodactyly Syndrome | |
| M | Tibial Hemimelia | |
| D | Tibial Hemimelia-Polydactyly-Club Foot | PITX1 |
| U | Tollner (1981) Polydactyly; Visceral Anomalies | |
| D | Townes-Brocks Syndrome | SALL1 |
| U | Triangular Thumb Epiphysis-Angulation Deformity | |
| D | Triphalangeal Thumb, Nonopposable | |
| D | Triphalangeal Thumbs and Dislocation of Patella | |
| D | Triphalangeal Thumbs with Brachyectrodactyly Ulna and Fibula, Absence of, with Severe Limb | |
| R | Deficiency | WNT7A |
| R | Ulnar Hypoplasia with Mental Retardation | |
| M | Ulnar Ray Dysgenesis with Postaxial Polydactyly and Renal Cystic Dysplasia | |
| D | Ulnar-Mammary Syndrome | TBX3 |
| R | Urbach (1986) Skeletal Dysplasia; Rhizomelia of Humeri | |
| R | Urioste (1996) Limb Deficiency-Vertebral Hypersegmentation-Absent Thymus | |
| U | VACTERL Association-Tibial Aplasia | |
| U | VATER Association | |
| R | VATER-Like Defects with Pulmonary Hypertension, Laryngeal Webs, and Growth Deficiency | |
| U | Weaver Syndrome | NSD1 |
| D | Weyers Acrofacial Dysostosis | EVC |
| U | Wieczorek (2002) Thumb Aplasia-Radial Aplasia-Microcephaly | ZBTB16 |
| U | Wiedemann (1985c) Macrocephaly; Polydactyly of Toes; Tibial Defect | |
| U | Wolter (1971) Papilla Nigra; Cleft Palate; Extra Thumb | |
| D | WT Syndrome-Pancytopenia-Hand Defects | |
| D | Zannolli (2008) Polydactyly-Ectodermal Dysplasia |
Table 2. Genes that, when mutated, can cause more than one clinically distinct phenotype in humans
| Gene | Clinical Entity |
|---|---|
| CD96 | C syndrome C-like syndrome |
| CXORF5 | Joubert syndrome* Oral-facial-digital syndrome type I |
| DYNC2H1 | Asphyxiating thoracic dystrophy type 3 Short-Rib polydactyly syndrome |
| EVC | Ellis-Van Creveld syndrome Weyers acrofacial dysostosis |
| FBLN1 | De Smet complex synpolydactyly Synpolydactyly* |
| FGFR2 | Apert syndrome Lacrimoauriculodentodigital syndrome |
| FLNB | Atelosteogenesis type III Spondylocarpotarsal dysostosis |
| GDF5 | Brachydactyly type C Chondrodysplasia, Grebe type |
| GLI3 | Greig cephalopolysyndactyly syndrome Pallister-Hall syndrome Acrocallosal syndrome Polydactyly, postaxial Polydactyly, preaxial* |
| INPP5B | Joubert syndrome* Mental retardation, truncal obesity, retinal dystrophy, and micropenis |
| MKKS | Bardet-Biedl syndrome McKusick-Kaufman syndrome |
| ROR2 | Brachydactyly type B Robinow syndrome |
| RPGRIP1L | Joubert syndrome* Meckel Syndrome |
| SHH** | Polydactyly, preaxial* Synpolydactyly* |
| WNT7A | Fibular a/hypoplasia, femoral bowing and poly-, syn-, and oligodactyly Ulna and fibula, absence of, with severe limb deficiency |
Footnotes:
* These phenotypes can be caused by mutations in more than one of the genes listed in the left column.
**These mutations are in the SHH ZRS (ZPA regulatory sequence) and not in the SHH gene proper
Polydactyly symptoms
Most of the time, polydactyly is discovered at birth when the baby is still in the hospital. Polydactyly may be present as an isolated finding, or they may occur as part of a syndrome, in which case other abnormalities are usually present.
Polydactyly diagnosis
Your health care provider will diagnose polydactyly based on your family history, medical history, and a physical exam.
Medical history questions may include:
- Have any other family members been born with extra fingers or toes?
- Is there a known family history of any of the disorders linked to polydactyly?
- Are there any other symptoms or problems?
Tests used to diagnose polydactyly:
- Chromosome studies
- Enzyme tests
- X-rays
- Metabolic studies
You may want to make a note of polydactyly in your personal medical record.
Extra digits may be discovered the first 3 months of pregnancy with ultrasound or a more advanced test called embryofetoscopy.
Prenatal ultrasound
Fetal finger buds can be seen using transvaginal ultrasound as early as 9 weeks and reliably by 13 weeks of pregnancy. Once polydactyly is established, a thorough ultrasound evaluation, especially of the heart, nervous system, limbs, and kidneys, to identify an associated syndrome (e.g., Meckel-Gruber syndrome, trisomy 13) should be performed. Follow-up ultrasound between 17 and 34 weeks with biometric profile is recommended to establish the diagnosis of isolated polydactyly 15.
Radiographs
Radiographs of the affected limb are recommended to show whether the rudimentary digit contains skeletal elements. The degree of deviation of the digit and the size of the articulating metacarpal or metatarsal also may be helpful in surgical planning.
Polydactyly treatment
A child with distal extremity anomalies experiences emotional stress 16. By age 3 years, the child has become aware of the anomaly. By age 7 years, the child has begun to experience the close scrutiny of his peers at school. For these reasons, along with others, surgical correction should be initiated early in life.
Polydactyly surgery
Surgical management depends greatly on the complexity and location of the deformity. Traditionally, postaxial polydactyly was managed by pediatricians with suture ligation and only syndactyly was treated in the operating room. However, the increased risk of painful neuromas when using suture ligation has led to the use of sharp excision for postaxial polydactyly. The accessory digital nerve in postaxial polydactyly needs to be identified and transected as far proximally as is safe in order to decrease the risk of neuroma. Soft tissue then covers the end of the divided nerve. In cases of preaxial and central polydactyly, treatment is variable and the surgeon looks to find a balance between aesthetics and functionality. Waiting until age 9-12 months is advisable to decrease anesthesia risk 17.
Conversely, if an infant has postaxial type B polydactyly (rudimentary extra digit attached to the ulnar side by a soft tissue stalk), excision in the neonatal nursery is a safe and simple procedure with consistently positive outcomes. Excision is done with a single swipe of a scalpel after the use of topical anesthesia 18.
Polydactyly surgery complications
Complications in the perioperative timeframe include those secondary to bleeding and anesthesia.
Later, decreased function due to ligamentous laxity or contracture can occur. Painful neuromas can also occur at the treatment site, especially when using suture ligation as therapy 19.
- Temtamy SA, McKusick VA. The genetics of hand malformations. Birth Defects Orig Artic Ser. 1978. 14(3):i-xviii, 1-619.[↩][↩]
- Entezami M, Albig M, Knoll U et-al. Ultrasound Diagnosis of Fetal Anomalies. Thieme. (2003) ISBN:1588902129.[↩]
- Terry R. Yochum, Lindsay J. Rowe (Editor) Essentials of Skeletal Radiology, 2 Vol. Set.[↩]
- Supernumerary Digit. https://emedicine.medscape.com/article/1113584-overview[↩][↩][↩][↩]
- Polydactyly. N Engl J Med 2011; 365:2122 DOI: 10.1056/NEJMicm1100857 https://www.nejm.org/doi/full/10.1056/NEJMicm1100857[↩]
- Hosalkar HS, Shah H, Gujar P, Kulkarni AD. Crossed polydactyly. J Postgrad Med. 1999 Jul-Sep. 45(3):90-2.[↩]
- Wattanarat O, Kantaputra PN. Preaxial polydactyly associated with a MSX1 mutation and report of two novel mutations. Am J Med Genet A. 2015 Oct 13.[↩]
- Bouldin CM, Harfe BD. Aberrant FGF signaling, independent of ectopic hedgehog signaling, initiates preaxial polydactyly in Dorking chickens. Dev Biol. 2009 Oct 1. 334 (1):133-41.[↩][↩]
- Muragaki Y, Mundlos S, Upton J, Olsen BR. Altered growth and branching patterns in synpolydactyly caused by mutations in HOXD13. Science. 1996 Apr 26. 272(5261):548-51.[↩]
- Son SH, Kim YJ, Kim ES et-al. A case of McKusick-Kaufman syndrome. Korean J Pediatr. 2011;54 (5): 219-23. doi:10.3345/kjp.2011.54.5.219[↩]
- Tore HG, Mckinney AM, Nagar VA et-al. Syndrome of megalencephaly, polydactyly, and polymicrogyria lacking frank hydrocephalus, with associated MR imaging findings. AJNR Am J Neuroradiol. 2009;30 (8): 1620-2. doi:10.3174/ajnr.A1566[↩]
- Poretti A, Brehmer U, Scheer I et-al. Prenatal and neonatal MR imaging findings in oral-facial-digital syndrome type VI. AJNR Am J Neuroradiol. 2008;29 (6): 1090-1. doi:10.3174/ajnr.A1038[↩]
- Anomalies of the fetal skeleton: sonographic findings. R A Bowerman. American Journal of Roentgenology 1995 164:4, 973-979 https://www.ajronline.org/doi/pdf/10.2214/ajr.164.4.7726060[↩][↩][↩]
- Polydactyly: How many disorders and how many genes: 2010 update. Dev Dyn. 2011 May; 240(5): 931–942. DOI: 10.1002/dvdy.22609 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3088011/[↩][↩]
- Bromley B, Shipp TD, Benacerraf B. Isolated polydactyly: prenatal diagnosis and perinatal outcome. Prenat Diagn. 2000 Nov. 20(11):905-8.[↩]
- Eskandari MM, Oztuna V, Demirkan F. Late psychosocial effects of congenital hand anomaly. Hand Surg. 2004 Dec. 9(2):257-9.[↩]
- Dijkman R, Selles R, van Rosmalen J, Hülsemann W, Mann M, Habenicht R, et al. A clinically weighted approach to outcome assessment in radial polydactyly. J Hand Surg Eur Vol. 2015 Aug 28.[↩]
- Katz K, Linder N. Postaxial type B polydactyly treated by excision in the neonatal nursery. J Pediatr Orthop. 2011 Jun. 31 (4):448-9.[↩]
- Hartzell TL, Taylor H. Traumatic amputation of a supernumerary digit: a 16-year-old boy’s perspective of suture ligation. Pediatr Dermatol. 2009 Jan-Feb. 26 (1):100-2.[↩]
