This condition is normally discovered at birth. If other symptoms are present, a specific syndrome may be indicated. Diagnosis of a specific syndrome is based on family history, medical history, and a physical exam. Webbed toes are also known as "twin toes," "duck toes," "turkey toes" and "tiger toes."

Severity can vary. Most cases involve the second and third toes but any number of toes can be involved. In some cases the toes are joined part way while in some the webbing can extend right up to the nails. In some cases the entire toes, including the nails and bones, can be fused.

Webbed toes is the common name for syndactyly affecting the feet. It is characterised by the fusion of two or more digits of the feet. This is normal in many birds, such as ducks; amphibians, such as frogs; and mammals, such as kangaroos. In humans it is considered unusual, occurring in approximately one in 2,000 to 2,500 live births.

There are various levels of webbing, from partial to complete. For example, the rare Hose's civet, a viverrid endemic to northern Borneo, has partially webbed feet. Most commonly the second and third toes are webbed or joined by skin and flexible tissue. This can reach either part way up or nearly all the way up the toe.

The accessory nail of the fifth toe is a physical trait of the small toe, where a minuscule "sixth toenail" is present in the outer corner of the nail situated on the smallest toe. It is commonly perceived to be especially prevalent amongst Han Chinese;.

Onychogryphosis (also known as onychogryposis or ram's horn nails) is a hypertrophy that may produce nails resembling claws or a ram's horn.

Additional findings that may be present in HFGS according to the latest research are:

- Limited metacarpophalangeal flexion of the thumb or limited ability to oppose the thumb and fifth finger

- Hypoplastic thenar eminences

- Medial deviation of the great toe (hallux varus), a useful diagnostic sign when present

- Small great toenail

- Fifth-finger clinodactyly, secondary to a shortened middle phalanx

- Short feet

- Altered dermatoglyphics of the hands; when present, primarily involving distal placement of the axial triradius, lack of thenar or hypothenar patterning, low arches on the thumbs, thin ulnar loops (deficiency of radial loops and whorls), and a greatly reduced ridge count on the fingers

Radiographic findings

- Hypoplasia of the distal phalanx and first metacarpal of the thumbs and great toes

- Pointed distal phalanges of the thumb

- Lack of normal tufting of the distal phalanges of the great toes

- Fusions of the cuneiform to other tarsal bones or trapezium-scaphoid fusion of the carpals

- Short calcaneus

- Occasional bony fusions of the middle and distal phalanges of the second, third, fourth, or fifth toes

- Delayed carpal or tarsal maturation

- Metacarpophalangeal profile reflecting shortening of the first metacarpal, the first and second phalanges, and the second phalanx of the second and fifth digits

Urogenital Defects

Females may have the following:

- Vesicoureteral reflux secondary to ureteric incompetence

- Ectopic ureteral orifices

- Trigonal hypoplasia

- Hypospadiac urethra

- Subsymphyseal epispadias

- Patulous urethra

- Urinary incontinence (related to structural anomalies and weakness of the bladder sphincter muscle)

- Small hymenal opening

- Various degrees of incomplete Müllerian fusion with or without two cervices or a longitudinal vaginal septum

Males may have the following:

- Retrograde ejaculation (related to structural anomalies and weakness of the bladder sphincter muscle)

Coffin–Siris Syndrome is a rare genetic disorder that causes developmental delays and absent fifth finger and toe nails.

There had been 31 reported cases by 1991. The numbers of occurrence since then has grown and is reported to be around 80.

The differential includes Nicolaides–Baraitser syndrome.

Onychogryphosis may be caused by trauma or peripheral vascular disease, but most often secondary to self-neglect and failure to cut the nails for extended periods of time. This condition is most commonly seen in the elderly.

Hand-foot-genital syndrome (HFGS) is characterized by limb malformations and urogenital defects. Mild bilateral shortening of the thumbs and great toes, caused primarily by shortening of the distal phalanx and/or the first metacarpal or metatarsal, is the most common limb malformation and results in impaired dexterity or apposition of the thumbs. Urogenital abnormalities include abnormalities of the ureters and urethra and various degrees of incomplete Müllerian fusion in females and hypospadias of variable severity with or without chordee in males. Vesicoureteral reflux, recurrent urinary tract infections, and chronic pyelonephritis are common; fertility is normal.

Clinodactyly (from the Ancient Greek κλίνειν ' meaning "to bend" and δάκτυλος ' meaning "digit") is a medical term describing the curvature of a digit (a finger or toe) in the plane of the palm, most commonly the fifth finger (the "little finger") towards the adjacent fourth finger (the "ring finger").

It is a fairly common isolated anomaly which often goes unnoticed, but also occurs in combination with other abnormalities in certain genetic syndromes.

The diagnosis is based on the following clinical findings:

- microcephaly

- clinodactyly and shortness of index and little fingers

- syndactyly of 2nd & 3rd and 4th & 5th toe

- short palpebral fissures

- esophageal and/or duodenal atresia

The trait can be observed on either one or both feet, where there is a separation of the toenail situated on the smallest toe. The separated part of the nail forms a smaller "sixth toenail" on the corner of the larger, or "main" section of the toenail, on the outermost side of the foot, which protrudes outwards from the corner of the larger nail. The additional "nail" can be cut with a nail clipper, just like any other nail.

The groove begins on the lower and internal side of the base of the fifth toe, usually according to the plantar-digital fold. The groove becomes gradually deeper and more circular. The rate of spread is variable, and the disease may progress to a full circle in a few months, or still be incomplete after years. In about 75 per cent both feet are affected, though not usually to the same degree. There is no case reported where it begins in any other toe than the fifth, while there is occasionally a groove on the fourth or third toe. The distal part of the toe swells and appears like a small “potato”. The swelling is due to lymphatic edema distal to the constriction. After a time crusts can appear in the groove which can be infected with staphylococcus.

While the groove becomes deeper, compression of tendons, vessels and nerves occurs. Bone is absorbed by pressure, without any evidence of infection. After a certain time all structures distal the stricture are reduced to an avascular cord. The toe’s connection to the foot becomes increasingly slender, and if it is not amputated, it spontaneously drops off without any bleeding. Normally it takes about five years for an autoamputation to occur.

Cole describes four stages of ainhum:

Pain is present in about 78% of cases. Slight pain is present in the earliest stage of ainhum, caused by pressure on the underlying nerves. Fracture of the phalanx or chronic sepsis is accompanied with severe pain.

Malalignment of the nail plate is a congenital malalignment of the nail of the great toe, and is often misdiagnosed although it is a common condition.

The cause of in-toeing can be differentiated based on the location of the disalignment. The variants are:

- Curved foot (metatarsus adductus)

- Twisted shin (tibial torsion)

- Twisted thighbone (femoral anteversion)

Diplopodia is a congenital anomaly in tetrapods that involves duplication of elements of the foot on the hind limb. It comes from the Greek roots diplo = "double" and pod = "foot". Diplopodia is often found in conjunction with other structural abnormalities and can be lethal. It is more extreme than polydactyly, the presence of extra digits.

The tibia or lower leg slightly or severely twists inward when walking or standing.

Cardiofaciocutaneous Syndrome (CFC syndrome) is an extremely rare and serious genetic disorder.

It is characterized by the following:

- Distinctive facial appearance

- Unusually sparse, brittle, curly scalp hair

- A range of skin abnormalities from dermatitis to thick, scaly skin over the entire body (generalized ichthyosis)

- Heart malformations (congenital or appearing later) especially an obstruction of the normal flow of blood from the lower right ventricle of the heart to the lungs (valvar pulmonary stenosis)

- Delayed growth

- Foot abnormalities (extra toe or fusion of two or more toes)

Some individuals have preaxial polydactyly in the feet (unilateral in one, bilateral in 13), consisting of a small extra biphalangeal toe, in most cases with an associated rudimentary extra metatarsal, lying in a soft tissue web between the hallux and second toe. In some cases, this was accompanied by hypoplasia of the head of the first metatarsal and absence of both phalanges of the hallux.

Acropectoral syndrome is an autosomal dominant skeletal dysplasia syndrome affecting the hands, feet, sternum, and lumbosacral spine. A recently proposed candidate gene for preaxial polydactyly is LMBR1, encoding a novel transmembrane receptor, which may be an upstream regulator of SHH. The LMBR1 gene is on human chromosome 7q36.

There is no consensus on what degree of angulation justifies a diagnosis, an incline between 15° and 30° is typical. A similar-sounding term, camptodactyly, is a fixed flexion deformity of a digit.

Ainhum (from Portuguese, pronounced "īn-yoom´", "i´num" or "ān´hum"; also known as dactylolysis spontanea) is a painful constriction of the base of the fifth toe frequently followed by bilateral spontaneous autoamputation a few years later.

In clubfoot one or both feet are rotated inwards and downwards. The affected foot, calf, and leg may be smaller than the other. In about half of those affected, both feet are involved. Most cases are not associated with other problems. Without treatment, people walk on the sides of their feet which causes issues with walking.

Plum syndrome is a very rare genetic disorder. It is characterized by retinal non-attachment, colobomata, odd facies, eyes set wide, flat face, dislocated hip, abnormal big toe, contractures of the extremities, cleft lip and mono-segmented leucocytes. There may be associated learning difficulties.

Named by Dr. C.M. Plum.

Individuals with the disorder usually have distinctive malformations of the craniofacial area including an unusually large head (macrocephaly), prominent forehead, and abnormal narrowing of both sides of the forehead (bitemporal constriction); The nose can be upturned and short with a low nasal bridge; and large ears that are abnormally rotated toward the back of the head. In many cases, affected individuals also have downward slanting eyelid folds, widely spaced eyes, drooping of the upper eyelids, inward deviation of the eyes, and other eye abnormalities including absent eyebrows and eyelashes.

The Pai Syndrome is a rare subtype of frontonasal dysplasia. It is a triad of developmental defects of the face, comprising midline cleft of the upper lip, nasal and facial skin polyps and central nervous system lipomas. When all the cases are compared, a difference in severity of the midline cleft of the upper lip can be seen. The mild form presents with just a gap between the upper teeth. The severe group presents with a complete cleft of the upper lip and alveolar ridge.

Nervous system lipomas are rare congenital benign tumors of the central nervous system, mostly located in the medial line and especially in the corpus callosum. Generally, patients with these lipomas present with strokes. However, patients with the Pai syndrome don’t. That is why it is suggested that isolated nervous system lipomas have a different embryological origin than the lipomas present in the Pai syndrome. The treatment of CNS lipomas mainly consists of observation and follow up.

Skin lipomas occur relatively often in the normal population. However, facial and nasal lipomas are rare, especially in childhood. However, the Pai syndrome often present with facial and nasal polyps. These skin lipomas are benign, and are therefore more a cosmetic problem than a functional problem.

The skin lipomas can develop on different parts of the face. The most common place is the nose. Other common places are the forehead, the conjunctivae and the frenulum linguae. The amount of skin lipomas is not related to the severity of the midline clefting.

Patients with the Pai syndrome have a normal neuropsychological development.

Until today there is no known cause for the Pai syndrome.

The large variety in phenotypes make the Pai syndrome difficult to diagnose. Thus the incidence of Pai syndrome seems to be underestimated.