Synpolydactyly is a rare limb deformity characterized by a unique combination of syndactyly and polydactyly. Synpolydactyly has an autosomal dominant mode of inheritance often with reduced penetrance. Variants in HOXD13, FBLN1, GLI3, and TTC30B have been reported to underlie the etiology of synpolydactyly. Here, we describe a three-generational Pakistani family segregating a form of synpolydactyly which has not previously been reported that includes, severe hand involvement characterized by bilateral syndactyly of the third, fourth, and fifth fingers, accompanied by preaxial polydactyly in all affected family members. Synpolydactyly of the feet was absent and only one family member presented with unilateral syndactyly of the third, fourth, and fifth toes. Exome sequencing of DNA samples obtained from members of the family led to the identification of a missense variant in HOXD12 [NM_021193.4:c.512A>G, p.(Asn171Ser)] that segregates with the synpolydactyly. HOXD12 is expressed in the posterior half of developing limb and is involved in bone development by regulating digit formation and patterning. It has also been implicated in limb deformities in mice and humans. Although HOXD12 has been reported to be involved in the etiology of clubfoot, this is the first report of its involvement in etiology of synpolydactyly.

Preaxial polydactyly (PPD) is characterized by a supernumerary finger or duplication of digital parts on the radial aspect of the thumb. There is a wide phenotypic variety among presentations of PPD. Numerous classification systems have been created to categorize these phenotypes. Here, we present a rare case of PPD that does not fit into any of the known classification systems. The patient was born with a large nonosseous PPD. The patient was treated successfully with sharp excision, and pathology confirmed the diagnosis of a soft-tissue-only supernumerary digit containing unique features of vascular proliferation and subepidermal bullae. While this case is the only one of its kind, similar cases have been reported in the recent literature. Therefore, we should consider implementing this PPD phenotype into a classification system to guide patient counseling, clinical decision-making, and management.

Polydactyly is one of the most common hereditary limb malformations, characterized by presence of additional digits in hands and/or feet. It is present either in isolated form or in combination with other features. Preaxial polydactyly with extra digit on the outside of the thumb or big toe, and postaxial polydactyly with extra digit on the outside of the little finger or little toe are the two main forms of polydactyly. In the present study, two unrelated consanguineous families segregating PAP in an autosomal recessive manner were investigated. Whole exome sequencing, followed by segregation analysis using Sanger sequencing, revealed a homozygous missense variant [c.1792 G>A; p.(Gly598Arg); NM_005631.5] in the SMO in both families. Proteins SMO, PTCH, and GLI act as major components of the Sonic hedgehog pathway, which transmits signals to embryonic cells for cellular differentiation. Homology modeling revealed that the variant in SMO may disrupt proper protein folding and interaction with other molecules. Our study has revealed the second direct involvement of a sequence variant in the SMO causing isolated polydactyly. This study will highlight the importance of the inclusion of the SMO gene in screening individuals presenting polydactyly in hands and feet.

Polydactyly, which is the presence of an extra appendage on the hand or the foot, is a common congenital anomaly encountered in children. It may be an isolated finding or found in conjunction with other congenital anomalies and syndromes. Polydactyly can occur in the hands or the feet. In the hand, it may occur as radial polydactyly (pre-axial polydactyly) or ulnar polydactyly (post-axial polydactyly (PAP)). Depending upon the side of occurrence, it may be medial, that is, toward the little finger (called ulnar polydactyly) or lateral, that is, toward the thumb (called radial polydactyly). On the feet, the extra digit can either be present on the side of the great toe (called tibial polydactyly) or on the side of the little toe (called fibular polydactyly). In both the upper and the lower limbs, affection of the central three digits is called central polydactyly. Central tetrapolydactyly, which is the presence of an extra appendage on all four limbs, is much more rarely encountered. This case report describes a 15-month-old female child who presented with findings of six digits on all four limbs and deviation of the left angle of mouth since birth. Her echocardiography showed a large atrial septal defect measuring 7 mm, with a left-to-right shunt. This is the first such case reported from all over the world from a tertiary care hospital with the aforementioned findings. Polydactyly, a very common congenital anomaly, should not be ignored in pediatric settings. It is important to diagnose associated features such as congenital heart diseases (CHDs), genitourinary abnormalities, and orofacial abnormalities to facilitate timely surgical correction and help improve the quality of life of those affected. A supernumerary digit, or polydactyly, is a congenital anomaly affecting the upper or lower extremities and is typically identified immediately after birth. Polydactyly is the most common congenital anomaly of the hand and foot, where affected individuals typically exhibit excessive fingers or toes, exceeding the usual count of 5. Parey, in the sixteenth century, documented individuals with more than the standard count of 5 fingers as having "superfluous fingers." Apart from Parey's historical description, artwork discovered in the southwestern "Four Corners" region of the United States portrays individuals with 6 digits on their hands and feet. This artwork is believed to have its origins in an early population that existed between AD 600 and 1280. The classification of polydactyly is contingent upon the location of the supernumerary digit. Preaxial polydactyly involves the radial or great toe side, postaxial polydactyly relates to the ulnar or fifth toe side, and central or mesoaxial polydactyly encompasses the second through fourth digits. Polydactyly is primarily an autosomal dominant anomaly and may manifest as an isolated condition or be associated with a syndrome. A comprehensive physical examination of newborns with polydactyly is imperative to evaluate the potential presence of associated syndromic disorders. This topic discusses the etiology and pathophysiology of polydactyly, as well as the significance of the interprofessional team in evaluating and treating affected patients. 

We aimed to subdivide modified type III radial polydactyly and evaluate the applied surgical procedures and outcomes according to the subtypes. This study included 32 thumbs of 32 patients treated for modified Wassel-Flatt type III radial polydactyly from March 2008 to December 2018. Each patient was subclassified into parallel, divergent, and convergent types according to the alignment of the duplicated digit. The parallel type was further divided according to the treatment method applied. The parallel A group comprised patients treated with reconstructing the radial collateral ligament of the interphalangeal (IP) joint after removing only the distal phalanx and preserving the proximal phalanx of the extra digit, and the parallel B group comprised patients treated with excision of the extra digit at the bifurcation site of the proximal phalanx. We evaluated the Japanese Society for Surgery of the Hand scores and radiographic angulation of the IP and metacarpophalangeal joints at a mean follow-up of 38 months. Fourteen cases were parallel type (6 and 8 in the parallel A and B groups, respectively), 14 were divergent type, and 4 were convergent type. Patients in the parallel A group had significantly better IP and metacarpophalangeal joint angulation and Japanese Society for Surgery of the Hand scores than those in the parallel B group. Patients in the parallel A group had significantly better Japanese Society for Surgery of the Hand scores than those in the divergent and convergent groups. Reconstructing the radial collateral ligament of the IP joint after removing only the distal phalanx and preserving the proximal phalanx of the extra digit was associated with better outcomes than the excision of the extra digit at the bifurcation site in the parallel type cases. The parallel type treated with proximal phalanx preservation and ligament reconstruction had better clinical outcomes than other types of modified Wassel-Flatt type III radial polydactyly. Prognostic IV.