This is a very rare situation, in which the extra digit is on the ring, middle or index finger. Of these fingers, the index finger is most often affected, whereas the ring finger is rarely affected.

This type of polydactyly can be associated with syndactyly, cleft hand and several syndromes.

Polysyndactyly presents various degrees of syndactyly affecting fingers three and four.

Most of the signs of MWS are present during the neonatal period. The most common signs at this state are multiple congenital joint contractures, dysmorphic features with mask-like face, blepharophimosis, ptosis, micrognathia, cleft or high arched palate, low-set ears, arachnodactyly, chest deformation as pectus, kyphoscoliosis and absent deep tendon reflexes are frequent minor malformations have also been described and consist of renal anomalies, cardiovascular abnormalities, hypospadias, omphalomesenteric duct, hypertriphic pyloric stenosis, duodenal bands, hyoplastic right lower lobe of the lung, displacement of the larynx to the right and vertebral abnormalities, cerebral malformations.

- 75% of children with MWS have blepharophimosis, small mouth, micrognathia, kyphosis/scoliosis, radio ulnar synostose and multiple contractures.

- They have severe developmental delay; congenital joint contractures and blepharophimosis should be present in every patient

- 2 out of 3 of the following signs should be manifested: post natal growth, mask-like faces, retardation, and decreased muscular mass.

- Some may require additional signs such as; micrognathia, high arched or cleft palate, low set ears, kyphoscoliosis.

- The symptoms of MWS are normally diagnosed during the newborn period

Classification is performed by using x-ray imaging to see the bone structures.

The natural history of MWS is not well known: many patients died in infancy and clinical follow-up has been reported in few surviving adults. However, diagnosis may be more difficult to establish in adults patients, such as: blepharophimosis, contractures, growth retardation, and developmental delay, whereas minor face anomalies are less noticeable as the patient grows older. Throughout the development of the patient from young child to older adult changes the behavior drastically, from kindness to restless and hyperactive to aggressive.

This condition exists in a variety of forms, ranging from partial absence of the tail bone regions of the spine to absence of the lower vertebrae, pelvis and parts of the thoracic and/or lumbar areas of the spine. In some cases where only a small part of the spine is absent, there may be no outward sign of the condition. In cases where more substantial areas of the spine are absent, there may be fused, webbed, or smaller lower extremities and paralysis. Bowel and bladder control is usually affected.

Symptoms begin in infancy and include:

- hypotonia

- areflexia

- amyotrophy

- variable degrees of dysgenesis of the corpus callosum

- mild to severe intellectual and developmental delay

- psychiatric problems including paranoid delusions, depression, hallucinations and autistic-like behavior

Classification of radial dysplasia is practised through different models. Some only include the different deformities or absences of the radius, where others also include anomalies of the thumb and carpal bones. The Bayne and Klug classification discriminates four different types of radial dysplasia. A fifth type was added by Goldfarb et al. describing a radial dysplasia with participation of the humerus. In this classification only anomalies of the radius and the humerus are taken in consideration. James and colleagues expanded this classification by including deficiencies of the carpal bones with a normal distal radius length as type 0 and isolated thumb anomalies as type N.

Type N: Isolated thumb anomaly

Type 0: Deficiency of the carpal bones

Type I: Short distal radius

Type II: Hypoplastic radius in miniature

Type III: Absent distal radius

Type IV: Complete absent radius

Type V: Complete absent radius and manifestations in the proximal humerus

The term absent radius can refer to the last 3 types.

Hemimelia comprises

- Fibular hemimelia, Congenital longitudinal deficiency of the fibula or Fibular longitudinal meromelia

- Tibial hemimelia, Congenital longitudenal deficiency of the tibia, Congenital aplasia and dysplasia of the tibia with intact fibula, Congenital longitudinal deficiency of the tibia or Tibial longitudinal meromelia

- Radial Hemimelia, Congenital longitudinal deficiency of the radius, Radial clubhand, Radial longitudinal meromelia or Radial ray agenesis

- Ulnar hemimelia, Congenital longitudinal deficiency of the ulna, Ulnar clubhand or Ulnar longitudinal meromelia

Caudal regression syndrome or sacral agenesis (or hypoplasia of the sacrum) is a congenital disorder in which there is abnormal fetal development of the lower spine—the caudal partition of the spine.

It occurs at a rate of approximately one per 25,000 live births.

It is characterized by developmental defects including cryptophthalmos (where the eyelids fail to separate in each eye), and malformations in the genitals (such as micropenis, cryptorchidism or clitoromegaly). Congenital malformations of the nose, ears, larynx and renal system, as well as mental retardation, manifest occasionally. Syndactyly (fused fingers or toes) has also been noted.

Radial dysplasia, also known as radial club hand or radial longitudinal deficiency, is a congenital difference occurring in a longitudinal direction resulting in radial deviation of the wrist and shortening of the forearm. It can occur in different ways, from a minor anomaly to complete absence of the radius, radial side of the carpal bones and thumb. Hypoplasia of the distal humerus may be present as well and can lead to stiffnes of the elbow. Radial deviation of the wrist is caused by lack of support to the carpus, radial deviation may be reinforced if forearm muscles are functioning poorly or have abnormal insertions. Although radial longitudinal deficiency is often bilateral, the extent of involvement is most often asymmetric.

The incidence is between 1:30,000 and 1:100,000 and it is more often a sporadic mutation rather than an inherited condition. In case of an inherited condition, several syndromes are known for an association with radial dysplasia, such as the cardiovascular Holt-Oram syndrome, the gastrointestinal VATER syndrome and the hematologic Fanconi anemia and TAR syndrome. Other possible causes are an injury to the apical ectodermal ridge during upper limb development, intrauterine compression, or maternal drug use (thalidomide).

Cubitus valgus is a medical deformity in which the forearm is angled away from the body to a greater degree than normal when fully extended. A small degree of cubitus valgus (known as the carrying angle) is acceptable and occurs in the general population.

When present at birth, it can be an indication of Turner syndrome or Noonan syndrome. It can also be acquired through fracture or other trauma. The physiological cubitus valgus varies from 3° to 29°. Women usually have a more pronounced Cubitus valgus than men. The deformity can also occur as a complication of fracture of the lateral condyle of the humerus, which may lead to tardy/delayed ulnar nerve palsy.

The opposite condition is cubitus varus ().

It is a congenital subluxation or dislocation of the ulna's distal end, due to malformation of the bones. Sometimes, minor abnormalities of other bone structures, often caused by disease or injury, such as a fracture of the distal end of the radius with upward displacement of the distal fragment. The deformity varies in degree from a slight protrusion of the lower end of the ulna, to complete dislocation of the inferior radio-ulnar joint with marked radial deviation of the hand. Severe deformities are associated with congenital absence or hypoplasia of the radius.

The male:female rate of this disorder is 1:4. The incidence is unknown, and there is no described racial predominance. Even though Madelung's Deformity is considered a congenital disorder, symptoms sometimes aren't seen until adulthood. In most cases, symptoms find their onset during midchildhood. At this age, the relatively slower growth of the ulnar and palmar part of the radius, leads to an increasingly progressive deformity. Pain and deformity are the main symptoms patients present with. Typical clinical presentation consists of a short forearm, anterior-ulnar bow of the radius and a forward subluxation of the hand on the forearm. As mentioned before, the severity of the disorder varies greatly, which also leads to a spectrum of presentation.

Ape hand deformity, also known as simian hand, is a deformity in humans who cannot move the thumb away from the rest of the hand. It is an inability to abduct the thumb. Abduction of the thumb refers to the specific capacity to orient the thumb perpendicularly to the ventral (palmar) surface of the hand. Opposition refers specifically the ability to "swing" the first metacarpal such that the tip of the thumb may touch the distal end of the 5th phalanx and if we put the hand on the table as the palm upward the thumb can not point to the sky. The Ape Hand Deformity is caused by damage to the distal median nerve (also called a Median Claw lesion), and subsequent loss of opponens pollicis muscle function. The name "ape hand deformity" is misleading, as apes have opposable thumbs.

It can occur with an injury of the median nerve either at the elbow or the wrist, impairing the thenar muscles and opponens pollicis muscle.

Ape hand deformity is one aspect of median nerve palsy, which is usually caused by deep injuries to the arm, forearm and wrist area.

Ape hand caused by median and ulnar nerve lesions

Children with amyoplasia often suffer from internally rotated shoulders, extended elbows, ulnar flexed wrists. The type of displacement of the hips and knees is more variable, and they often have club feet. Most children have symmetrical limb involvement.

About 10% of children with amyoplasia have evidence of vascular compromise including Intestinal atresia, abdominal wall defects, and gastroschisis.

Tracheal agenesis is a rare birth defect with a prevalence of less than 1 in 50,000, in which the trachea fails to develop. The defect is normally fatal, although occasional cases have been reported of long-term survival following surgical intervention.

There are three main types of tracheal agenesis, designated Types I, II and III.

In 2013, a case was reported of a South Korean child with tracheal agenesis who had been successfully treated after having been kept alive in an intensive care unit for the first two and a half years of her life. She then had an artificially created trachea implanted that had been created by tissue engineering using her own stem cells. The patient however later died from complications.

HEC syndrome is a syndrome characterized by hydrocephalus, endocardial fibroelastosis and cataracts.

Amyoplasia is a condition characterized by a generalized lack in the newborn of muscular development and growth, with contracture and deformity at most joints. It is the most common form of arthrogryposis.

It is characterized by the four limbs being involved, and by the replacement of skeletal muscle by dense fibrous and adipose tissue. Studies involving amyoplasia have revealed similar findings of the muscle tissue due to various causes including that seen in sacral agenesis and amyotrophic lateral sclerosis. So amyoplasia may also include an intermediate common pathway, rather than the primary cause of the contractors.

Ulnar–mammary syndrome or Schinzel syndrome is a cutaneous condition characterized by nipple and breast hypoplasia or aplasia.

It has been associated with TBX3.

Andermann syndrome also known as agenesis of corpus callosum with neuronopathy (ACCPN), Charlevoix disease among others is a very rare neurodegenerative genetic disorder that damages the nerves used to control muscles and related to sensation, and is often associated with agenesis of the corpus collosum.

It was first described by Eva Andermann et al. in 1972.

Eye agenesis is a medical condition in which people are born with no eyes.

In medicine, agenesis () refers to the failure of an organ to develop during embryonic growth and development due to the absence of primordial tissue. Many forms of agenesis are referred to by individual names, depending on the organ affected:

- Agenesis of the corpus callosum - failure of the Corpus callosum to develop

- Renal agenesis - failure of one or both of the kidneys to develop

- Phocomelia - failure of the arms or legs to develop

- Penile agenesis - failure of penis to develop

- Müllerian agenesis - failure of the uterus and part of the vagina to develop

- Agenesis of the gallbladder - failure of the Gallbladder to develop. A person may not realize they have this condition unless they undergo surgery or medical imaging, since the gallbladder is neither externally visible nor essential.

MURCS association (a variant of Mayer-Rokitansky-Küster-Hauser syndrome) is a very rare developmental disorder that primarily affects the reproductive and urinary systems involving MUllerian agenesis, Renal agenesis, Cervicothoracic Somite abnormalities. It affects only females.

Madelung's deformity is usually characterized by malformed wrists and wrist bones and is often associated with Léri-Weill dyschondrosteosis. It can be bilateral (in both wrists) or just in the one wrist.

It has only been recognized within the past hundred years.

Fraser syndrome (also known as Meyer-Schwickerath's syndrome, Fraser-François syndrome, or Ullrich-Feichtiger syndrome) is an autosomal recessive congenital disorder. Fraser syndrome is named for the geneticist George R. Fraser, who first described the syndrome in 1962.