Polydactyly is the most common congenital disorder that may occur in association with other birth defect or in isolation. It is classified as preaxial, postaxial or central.

In preaxial polydactyly, the duplication occurs in the first digit, while postaxial polydactyly involves duplication of the fifth digit.

In central polydactyly there is the duplication of the second, third and fourth finger. For upper extremity, the terms such as radial, central and ulnar are used, while terms such as tibial, central, and fibular are proposed for polydactyly in the lower extremity.

Rare occurrence of polydactyly is called “crossed polydactyly”, which involves the preaxial involvement of one extremity is coupled with the postaxial of the opposite end of the body [7].

• Short Stature

  Stature-Delayed Bone Age-Broad Nose * UFocal Dermal Hypoplasia, Morning Glory Anomaly, and Polymicrogyria305600XFocal Dermal Hypoplasia PORCN * UFranceschini (1994) Mask-Like Face; Ear Anomalies; Digital Malformations609640DFrias Syndrome136760MFrontonasal [ncbi.nlm.nih.gov]

  Verma, Stephanie Wallace, Charles Williams, Elaine Zackai, Jonathan Zonana, Conxi Lazaro, Kathleen Claes, Bruce Korf, Yolanda Martin, Eric Legius and Ludwine Messiaen, High Incidence of Noonan Syndrome Features Including Short Stature and Pulmonic Stenosis [doi.org]

  Microcephaly, short stature, syndactyly, intellectual disability (often labeled mental retardation), and a dysmorphic face are characteristic. [disorders.eyes.arizona.edu]

• Short Finger

  Other minor developmental anomalies, like short fingers and toes, are often passed from generation to generation. [nationalgeographic.com]

  They are looking for participants who only have problems with their limbs, such as fused or webbed fingers/toes, more than 5 fingers/toes, less than 5 fingers/toes, split hand and foot also called ectrodactyly, short fingers/toes, bent pinky fingers, [rarediseases.info.nih.gov]

• Brachydactyly

  Another challenge in studying hand anomalies is that the literature will often refer to certain malformation types (e.g., brachydactyly type E) without defining what this type is. [peds.ufl.edu]

  GDF5 302960XChonrdodysplasia Punctata 2, X-Linked Dominant EBP 601165RCleft Lip/Palate with Characteristic Facies, Intestinal Malrotation, and Lethal Congenital Heart Disease * UCOH Syndrome-Craniosynostosis; Bifid Thumb; Micropenis120400DColobomas-Brachydactyly [ncbi.nlm.nih.gov]

  Polydactyly sometimes also occurs in various genetic syndromes, including the Ellis–van Crevald syndrome and… Read More genetic disorder In malformation: Somatic characters …as fingers or toes (polydactyly, hypodactyly [ectrodactyly], brachydactyly), [britannica.com]

  Brachydactyly. Orphanet J Rare Dis. 2008;13:3–15. Google Scholar 19. Fairbank SM, Rozen WM, Coombs CJ. The pathogenesis of Kirner’s deformity: a clinical, radiological and histological study. J Hand Surg Eur Vol. 2015;40(6):633–7. [link.springer.com]

  Dysmorphism of extremities, including postaxial polydactyly, syndactyly or brachydactyly, is one of the earliest and most common manifestations of BBS. Renal involvement is observed in most affected individuals. [academic.oup.com]

• Thumb Hypoplasia

  Thumb Hypoplasia Classification These tables and images were adapted from a 2004 paper addressing radial ray digit defects and thumb hypoplasias. See the table below the images for explanation of this classification system. [peds.ufl.edu]

  Synostosis, Kirner’s deformity, brachydactyly, triphalangeal thumb, clinodactyly, camptodactyly, macrodactyly, thumb hypoplasia, congenital constriction band syndrome, and congenial trigger thumb occur as the most often hand anomalies in pediatric population [link.springer.com]

• Dermatitis

  There are several types of polydactyly, of varying frequency: Polydactyly alopecia seborrheic dermatitis Polydactyly cleft lip palate psychomotor retardation Polydactyly myopia syndrome Polydactyly postaxial dental and vertebral Polydactyly postaxial [fetalultrasound.com]

  Ear Anomalies; Digital Malformations609640DFrias Syndrome136760MFrontonasal Dysplasia ALX3 606155UFryns-Aftimos * UFryns-Lagae-Rizzo-Polydactyly-Growth Retardation-Spasticity-Urogenital * UGandhi (2008) * UGarrett-Tripp-MR; Polydactyly; Hair Absence; Dermatitis [ncbi.nlm.nih.gov]

• Alopecia

  There are several types of polydactyly, of varying frequency: Polydactyly alopecia seborrheic dermatitis Polydactyly cleft lip palate psychomotor retardation Polydactyly myopia syndrome Polydactyly postaxial dental and vertebral Polydactyly postaxial [fetalultrasound.com]

• Psychomotor Retardation

  There are several types of polydactyly, of varying frequency: Polydactyly alopecia seborrheic dermatitis Polydactyly cleft lip palate psychomotor retardation Polydactyly myopia syndrome Polydactyly postaxial dental and vertebral Polydactyly postaxial [fetalultrasound.com]

• Burning Sensation

  Erythromelalgia can also cause a painful, burning sensation or swelling of the affected areas. [rarediseases.org]

Laboratory studies

Since foot and hand polydactyly is associated with the congenital defects, genetic workup and medical examination are recommended. Polydactyly has also rarely been associated with congenital anomalies such as Down syndrome, Trisomy 13 and Meckel syndrome [8].

Imaging 

• Prenatal ultrasound: Transvaginal ultrasound at 9 weeks and 13 weeks is a reliable diagnostic tool as the fetal finger buds develop at this stage. If polydactyly is suspected, thorough ultrasound must be done to identify any associated syndrome, such as Trisomy 13 and Meckel Gruber syndrome. 
• Radiographs: In order to know if the skeletal elements contain a rudimentary digit, radiographs can be done [9].
• Histologic finding: Hyperkeratosis and acanthosis in the dermis are seen in patients with rudimentary polydactyly. 

Surgical management of polydactyly depends on the complexity of the condition (or deformity). The common treatment modality is the surgical removal. It is advised to wait for 9 to 12 months to avoid the risk associated with anesthesia [10].

Prognosis is excellent for children with polydactyly (isolated or syndactyly). The patient post surgery can use the fingers and the toes. In individuals or children with additional birth defects, the prognosis is poor [5].

Complications

Complications related to polydactyly is associated with the surgical intervention for managing polydactyly. 

Polydactyly can occur either as an isolated trait or with other syndromes. A positive family history in almost 30% of cases has been observed [4].

Knowledge of the prevalence of polydactyly is limited. Genetic and ethnic factors can influence of the nature of polydactyly in the general population.

Preaxial polydactyly is common in Asian populations (South China, Hong Kong and Japan) with 90% of all the reported cases observed in this population. Autosomal-dominant transmission is suspected in children with African Black and African American. In blacks, the occurrence of postaxial polydactyly is almost more frequent than in whites [2] [3].

Some other factors that increase the chances of polydactyly in children are:

• Male gender
• Low maternal education
• Recurrence of first-degree relatives

Mutation of the specific gene location causing limb development is responsible for polydactyly. In mammals, there is a cluster of the genes identified as homeobox or hox genes which corresponds to the 5 domains across the limb bud. It is found that the mutation of the HOXD13 gene is often associated with synpolydactyly.

No known preventive measures for polydactyly and syndatyly is known [11].

One of the congenital digital anomalies of the hand and foot is polydactyly. Often it appears in association with other birth defects. Polydactyly can be due to autosomal-dominant or autosomal-recessive gene mutation [1].

Definition

Polydactyly is a common type of congenital digital anomaly which manifests as an extra digit in the foot or hand.

Cause

Polydactyly can occur with the other syndromes or as an isolated case. It can occur due to autosomal-dominant or autosomal-recessive mutation. Family history, African race and male gender contribute to polydactyly.

Symptom

In polydactyly, there is an appearance of the extra digit in any limb. 

Diagnosis

Ultrasound at 9 and 13 weeks can help diagnose the condition at an early stage. Treatment (surgery) is prescribed after 12 months of birth. 

Treatment

Surgical removal of the extra digit is the recommended treating polydactyly.

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11. Rudolph, Colin D., and Abraham M. Rudolph, editors. Rudolph's Pediatrics. 21st ed. New York: McGraw-Hill, 2003.