Often there is a distinction made between conditions of the dorsal skin and plantar skin. Common examples include callus thickened skin, fungal infections of the skin (athlete's foot) or nails (onychomycosis), viral infection of verrucae, and ingrowing toenails that may cause bacterial nail infections (paronychia).

Corns and calluses are chunky tough layers of skin that develop on the foot to protect underlying skin from pressure and friction. Corns and calluses are very common and do not look pleasant. Corns and calluses generally need treatment only if they cause problems. For most people, the best treatment of corns and calluses is to eliminate the source of friction or pressure.

Ingrown toe nail is a disorder where the nail starts to grow into the soft fleshy area of the toe. It causes intense redness, pain and swelling. Ingrown toe nails often affect the big toe. The best treatment for ingrown toe nails is to get the nail partially or completely removed.

A foot deformity is a disorder of the foot that can be congenital or acquired.

Such deformities can include hammer toe, club foot, flat feet, pes cavus, etc.

Diseases of the foot generally are not limited, that is they are related to or manifest elsewhere in the body. However, the foot is often the first place some of these diseases or a sign or symptom of others appear. This is because of the foot's distance from the central circulation, the heart and its constant exposure to pressures from the ground and the weight of the body.

The foot may look simple but is a complex structure with 26 bones, 33 joints, numerous muscles, nerves and different ligament types. Any part of the foot can be affected. Some foot disorders may present with just a mild ache, but other foot disorders can be very serious and limit ability to walk or bear weight. Most minor cases of foot pain respond to home care treatments except when severe pain is present as it is a disabling condition and usually needs some type of medical attention. If foot pain is not treated in time, it can lead to long term disability and continuing damage to the foot.

Gerodermia osteodysplastica is characterized by symptoms and features which affect the connective tissues, skin and skeletal system.

These are: wrinkly, loose skin over the face, abdomen, and extremites (hands, feet) on the dorsal sides usually worsened by chronic joint laxity and hyperextensibility; fragmented elastic fibers of the skin that are reduced in number, with disorientation of collagen fibers; osteopenia and osteoporosis, with associated fractures; malar hypoplasia (underdeveloped cheek bone), maxillary hypoplasia (underdeveloped upper jaw), mandibular prognathism (protrusion of the lower jaw and chin), bowed long bones, platyspondyly (flattened spine) related to vertebral collapse; kyphoscoliosis (scoliosis with kyphosis, or "hunch back"), metaphyseal peg (an unusual outgrowth of metaphyseal tissue which protrudes into the epiphyseal region of the bone, near the knee); and the overall physical effects and facial appearance of dwarfism with premature aging.

Other features and findings include: intrauterine growth retardation, congenital hip dislocations, winged scapulae (shoulder blades), pes planus (fallen arches), pseudoepiphyses of the second metacarpals (upper bone of the fingers), hypotelorism (close-set eyes), malformed ears,

developmental delay,

failure to thrive and abnormal electroencephalograph (EEG) readings.

Dental and orthodontal abnormalities in addition to maxillary hypoplasia and mandibular prognathism have also been observed in gerodermia osteodysplastica. Including malocclusion of the dental arches (the maxilla and mandible), radiological findings in some cases have indicated significant overgrowth of the mandibular premolar and molar roots;

hypercementosis (overproduction of cementum) of the molars and maxillary incisors; enlarged, funnel-shaped mandibular lingula (spiny structures on the ramus of the mandible); and a radiolucent effect on portions of many teeth, increasing their transparency to x-rays.

Gerodermia osteodysplastica (GO), also called geroderma osteodysplasticum and Walt Disney dwarfism, is a rare autosomal recessive connective tissue disorder included in the spectrum of cutis laxa syndromes.

Usage of the name "Walt Disney dwarfism" is attributed to the first known case of the disorder, documented in a 1950 journal report, in which the authors described five affected members from a Swiss family as having the physical appearance of dwarves from a Walt Disney film.

The terms "geroderma" or "gerodermia" can be used interchangeably with "osteodysplastica" or "osteodysplasticum", with the term "hereditaria" sometimes appearing at the end.

Many medical professionals can diagnose a flat foot by examining the patient standing or just looking at them. On going up onto tip toe the deformity will correct when this is a flexible flat foot in a child with lax joints. Such correction is not seen in adults with a rigid flat foot.

An easy and traditional home diagnosis is the "wet footprint" test, performed by wetting the feet in water and then standing on a smooth, level surface such as smooth concrete or thin cardboard or heavy paper. Usually, the more the sole of the foot that makes contact (leaves a footprint), the flatter the foot. In more extreme cases, known as a kinked flatfoot, the entire inner edge of the footprint may actually bulge outward, where in a normal to high arch this part of the sole of the foot does not make contact with the ground at all.

On plain radiography, flat feet can be diagnosed and graded by several measures, the most important being the talonavicular coverage angle, the calcaneal pitch, and the talar-1st metatarsal angle (Meary's angle). The talonavicular coverage angle is abnormally laterally rotated in flat feet. It is normally up to 7 degrees laterally rotated, so a greater rotation indicates flat feet.

Aneuploidy is often fatal, but in this case there is "X-inactivation" where the effect of the additional gene dosage due to the presence of extra X chromosomes is greatly reduced.

Much like Down syndrome, the mental effects of 49,XXXXY syndrome vary. Impaired speech and behavioral problems are typical. Those with 49,XXXXY syndrome tend to exhibit infantile secondary sex characteristics with sterility in adulthood and have some skeletal anomalies. Skeletal anomalies include:

- Genu valgum

- Pes cavus

- Fifth finger clinodactyly

The effects also include:

- Cleft palate

- Club feet

- Respiratory conditions

- Short or/and broad neck

- Low birth weight

- Hyperextensible joints

- Short stature

- Narrow shoulders

- Coarse features in older age

- Hypertelorism

- Epicanthal folds

- Prognathism

- Gynecomastia (rare)

- Muscular hypotonia

- Hypoplastic genitalia

- Cryptorchidism

- Congenital heart defects

- A very round face in infancy

Studies have shown children and adolescents with flat feet are a common occurrence. The human arch develops in infancy and early childhood as part of normal muscle, tendon, ligament and bone growth . Flat arches in children usually become high arches as the child progresses through adolescence and into adulthood. Since children are unlikely to suspect or identify flat feet on their own, it is important for adult caregivers to check on this themselves. Besides visual inspection, caregivers should notice when a child's gait is abnormal. Children who complain about calf muscle pains, arch pain, or any other pains around the foot area may be developing or have developed flat feet. Children with flat feet are at a higher risk of developing knee, hip, and back pain. A recent randomized controlled trial found no evidence for the efficacy of treatment of flat feet in children either from expensive prescribed orthotics i.e (shoe inserts) or less expensive over-the-counter orthotics. As a symptom itself, flat feet usually accompany genetic musculoskeletal conditions such as dyspraxia, ligamentous laxity or hypermobility.

Individuals affected by ischiopatellar dysplasia commonly have abnormalities of the patella and pelvic girdle, such as absent or delayed patellar and ischial ossification as well as infra-acetabular axe-cut notches. Patellae are typically absent or small in these individuals, when patellae are present they are small and laterally displaced or dislocated. In addition, abnormalities in other parts of their skeleton and dysmorphic features are common in those affected. Other features that have been identified in patients with ischiopatellar dysplasia include foot anomalies, specifically flat feet (pes planus), syndactylism of the toes, short fourth and fifth toes, and a large gap between the first and second toes, femur anomalies, cleft palate, and craniofacial dysmorphisms.

As with certain cases of flat feet, high arches may be painful due to metatarsal compression; however, high arches— particularly if they are flexible or properly cared-for—may be an asymptomatic condition.

People with pes cavus sometimes—though not always—have difficulty finding shoes that fit and may require support in their shoes. Children with high arches who have difficulty walking may wear specially-designed insoles, which are available in various sizes and can be made to order.

Individuals with pes cavus frequently report foot pain, which can lead to a significant limitation in function. The range of complaints reported in the literature include metatarsalgia, pain under the first metatarsal, plantar fasciitis, painful callosities, ankle arthritis, and Achilles tendonitis.

There are many other symptoms believed to be related to the cavus foot. These include shoe-fitting problems, lateral ankle instability, lower limb stress fractures, knee pain, iliotibial band friction syndrome, back pain and tripping.

Foot pain in people with pes cavus may result from abnormal plantar pressure loading because, structurally, the cavoid foot is regarded as being rigid and non-shock absorbent and having reduced ground contact area. There have previously been reports of an association between excessive plantar pressure and foot pathology in people with pes cavus.

On weightbearing projectional radiography, pes cavus can be diagnosed and graded by several features, the most important being medial peritalar subluxation, increased calcaneal pitch (variable) and abnormal "talar-1st metatarsal angle" (Meary's angle). Medial peritalar subluxation can be demonstrated by a medially rotated talonavicular coverage angle.

Ischiopatellar dysplasia is a rare autosomal dominant disorder characterized by a hypoplasia of the patellae as well as other bone anomalies, especially concerning the pelvis and feet.

Recurrent otitis media is frequently associated with proximal 18q- and, in some cases, may cause conductive hearing loss. This may be resolved with the placement of PE tubes.

Individuals with distal 18q- may have problems with reflux. Hernias have also been reported.

People with distal 18q- frequently have conductive and/or sensorineural hearing loss. The degree of hearing loss may vary from a mild to a severe loss.

Children with 18p- have an increased incidence of ear infections, often requiring the placement of PE tubes.

Hypotonia is a common finding. Seizures are present in about half of individuals.

Chronic constipation is a frequent complaint in the 18p- population. Other abdominal abnormalities that have been reported include inguinal hernias; malrotation of the gut; and abnormalities of the spleen.

The syndrome gets its name from the characteristic cry of affected infants, which is similar to that of a meowing kitten, due to problems with the larynx and nervous system. About 1/3 of children lose the cry by age of 2 years. Other symptoms of cri du chat syndrome may include:

- feeding problems because of difficulty in swallowing and sucking;

- low birth weight and poor growth;

- severe cognitive, speech, and motor delays;

- behavioral problems such as hyperactivity, aggression, outbursts, and repetitive movements;

- unusual facial features which may change over time;

- excessive drooling;

- small head and jaw;

- wide eyes;

- skin tags in front of eyes.

Other common findings include hypotonia, microcephaly, growth retardation, a round face with full cheeks, hypertelorism, epicanthal folds, down-slanting palpebral fissures, strabismus, flat nasal bridge, down-turned mouth, micrognathia, low-set ears, short fingers, single palmar creases, and cardiac defects (e.g., ventricular septal defect [VSD], atrial septal defect [ASD], patent ductus arteriosus [PDA], tetralogy of Fallot). Infertility is not associated with Cri du chat.

It has also been observed that people with the condition have difficulties communicating. While levels of proficiency can range from a few words to short sentences, it is often recommended by medical professionals for the child to undergo some sort of speech therapy/aid with the help of a professional.

Less frequently encountered findings include cleft lip and palate, preauricular tags and fistulas, thymic dysplasia, intestinal malrotation, megacolon, inguinal hernia, dislocated hips, cryptorchidism, hypospadias, rare renal malformations (e.g., horseshoe kidneys, renal ectopia or agenesis, hydronephrosis), clinodactyly of the fifth fingers, talipes equinovarus, pes planus, syndactyly of the second and third fingers and toes, oligosyndactyly, and hyperextensible joints. The syndrome may also include various dermatoglyphics, including transverse flexion creases, distal axial triradius, increased whorls and arches on digits, and a single palmar crease.

Late childhood and adolescence findings include significant intellectual disability, microcephaly, coarsening of facial features, prominent supraorbital ridges, deep-set eyes, hypoplastic nasal bridge, severe malocclusion, and scoliosis.

Affected females reach puberty, develop secondary sex characteristics, and menstruate at the usual time. The genital tract is usually normal in females except for a report of a bicornuate uterus. In males, testes are often small, but spermatogenesis is thought to be normal.

49,XXXXY syndrome is an extremely rare aneuploidic sex chromosomal abnormality. It occurs in approximately 1 out of 85,000 to 100,000 males.

Symptoms of CMT usually begin in early childhood or early adulthood, but can begin later. Some people do not experience symptoms until their early thirties or forties. Usually, the initial symptom is foot drop early in the course of the disease. This can also cause hammer toe, where the toes are always curled. Wasting of muscle tissue of the lower parts of the legs may give rise to a "stork leg" or "inverted champagne bottle" appearance. Weakness in the hands and forearms occurs in many people as the disease progresses.

Loss of touch sensation in the feet, ankles and legs, as well as in the hands, wrists and arms occur with various types of the disease. Early and late onset forms occur with 'on and off' painful spasmodic muscular contractions that can be disabling when the disease activates. High-arched feet (pes cavus) or flat-arched feet (pes planus) are classically associated with the disorder. Sensory and proprioceptive nerves in the hands and feet are often damaged, while unmyelinated pain nerves are left intact. Overuse of an affected hand or limb can activate symptoms including numbness, spasm, and painful cramping.

Symptoms and progression of the disease can vary. Involuntary grinding of teeth as well as squinting are prevalent and often go unnoticed by the person affected. Breathing can be affected in some; so can hearing, vision, as well as the neck and shoulder muscles. Scoliosis is common, causing hunching and loss of height. Hip sockets can be malformed. Gastrointestinal problems can be part of CMT, as can difficulty chewing, swallowing, and speaking (due to atrophy of vocal cords). A tremor can develop as muscles waste. Pregnancy has been known to exacerbate CMT, as well as severe emotional stress. Patients with CMT must avoid periods of prolonged immobility such as when recovering from a secondary injury as prolonged periods of limited mobility can drastically accelerate symptoms of CMT.

Pain due to postural changes, skeletal deformations, muscle fatigue and cramping is fairly common in people with CMT. It can be mitigated or treated by physical therapies, surgeries, and corrective or assistive devices. Analgesic medications may also be needed if other therapies do not provide relief from pain. Neuropathic pain is often a symptom of CMT, though, like other symptoms of CMT, its presence and severity varies from case to case. For some people, pain can be significant to severe and interfere with daily life activities. However, pain is not experienced by all people with CMT. When neuropathic pain is present as a symptom of CMT, it is comparable to that seen in other peripheral neuropathies, as well as postherpetic neuralgia and complex regional pain syndrome, among other diseases.

Cri du chat syndrome, also known as chromosome 5p deletion syndrome, 5p− syndrome (pronounced "Five P Minus") or Lejeune’s syndrome, is a rare genetic disorder due to chromosome deletion on chromosome 5. Its name is a French term ("cat-cry" or "call of the cat") referring to the characteristic cat-like cry of affected children. It was first described by Jérôme Lejeune in 1963. The condition affects an estimated 1 in 50,000 live births across all ethnicities and is more common in females by a 4:3 ratio.

The most notable features of Wilson-Turner Syndrome are intellectual disability, obesity, hypogonadism, gynecomastia, and distinct facial features. All of the symptoms are chronic. Affected females are known to have less severe signs and symptoms than males. Female carriers of the disorder may have none or mild symptoms.

- Intellectual Disability is the limitation in an individual's mental functioning and skills. Patients of Wilson-Turner Syndrome have mental disability generally ranging from mild to severe, more frequently on the former. This symptom often coincides with delay in speech development and the occurrence of mood swings. Most males were noted to have a quiet and a cheerful disposition. However, individuals who displayed aggression and became easily upset were also seen. Children will display a delay in speech development often combined with excessive drooling and low voice tone. Some of the studied male patients had speech impairment ranging from little or no speech to minor stuttering.

- Obesity is the accumulation of excess fat on the body. Individuals with Wilson-Turner Syndrome are characterized to have truncal obesity, meaning the fat has accumulated in one's middle. Truncal obesity is often related to heart disease, kidney disease, and lowered blood immune system. Truncal obesity in this disorder becomes more apparent around the age of puberty.

- Tapered fingers is when one end of the finger is diminished in thickness, causing the ends of the fingers to appear pointed. This deformity is not debilitating in any particular manner. In addition to tapered fingers, both hands and feet tend to be small. Some males were observed to have pes planus, also known as flat feet.

- Hypogonadism is a condition in which the gonads have a decrease in function. This condition may result from the lack of sex hormone synthesis, such as androgen and estrogen. Hormones produced by the gonads may also decrease. Hypogonadism also influences the onset of other conditions of the Wilson-Turner Syndrome, such as gynecomastia and decreased testes size in males. It can also cause short stature in men and women. In addition to little genital development, pubic and body hair are scant.

- Some of the facial features that are associated with Wilson-Turner Syndrome include small head circumference, high forehead, prominent ears, and nose with a flattened bridge. There have been cases of a moderately high palate. Low muscle tone and subcutaneous swelling in facial tissue has also been noted. Thick eyebrows are also common. However, there has been reported cases where individuals had none of the mentioned facial features, which shows phenotypic abnormalities have possible environmental influences.

- Gynecomastia is a non-cancerous increase in male breast tissue. It is believed that disturbances in the endocrine system leads to an increase in estrogen and androgen hormones lead to the development of gynecomastia. A key feature of gynecomastia is a rubbery or firm glandular subcutaneous chest tissue that is palpated under the areola of the nipple, instead of the soft fatty tissue. There can also be in increase in diameter of the areola asymmetry in the chest tissue. The breast enlargement can occur in one or both side. Similar to truncal obesity, gynecomastia becomes apparent around the age of puberty.

Dural ectasia, the weakening of the connective tissue of the dural sac encasing the spinal cord, can result in a loss of quality of life. It can be present for a long time without producing any noticeable symptoms. Symptoms that can occur are lower back pain, leg pain, abdominal pain, other neurological symptoms in the lower extremities, or headachessymptoms which usually diminish when lying flat. On X-ray however dural ectasia is not often visible in the early stages. A worsening of symptoms might warrant an MRI of the lower spine. Dural ectasia that has progressed to this stage would appear in an MRI as a dilated pouch wearing away at the lumbar vertebrae. Other spinal issues associated with Marfan syndrome include degenerative disc disease, spinal cysts and dysfunction of the autonomic nervous system.

Most of the readily visible signs are associated with the skeletal system. Many individuals with Marfan syndrome grow to above-average height, and some have disproportionately long, slender limbs with thin, weak wrists and long fingers and toes. Besides affecting height and limb proportions, people with Marfan syndrome may have abnormal lateral curvature of the spine (scoliosis), thoracic lordosis, abnormal indentation (pectus excavatum) or protrusion (pectus carinatum) of the sternum, abnormal joint flexibility, a high-arched palate with crowded teeth and an overbite, flat feet, hammer toes, stooped shoulders, and unexplained stretch marks on the skin. It can also cause pain in the joints, bones and muscles. Some people with Marfan have speech disorders resulting from symptomatic high palates and small jaws. Early osteoarthritis may occur. Other signs include limited range of motion in the hips due to the femoral head protruding into abnormally deep hip sockets.