Absent radius is a very rare medical condition in which the radius bone

Radius (bone)

The radius is one of the two large bones of the forearm, the other being the ulna. It extends from the lateral side of the elbow to the thumb side of the wrist and runs parallel to the ulna, which exceeds it in length and size. It is a long bone, prism-shaped and slightly curved longitudinally...

 is not developed. This results in a typical position of the arm in which the wrist is plantarflexed and radially deviated.

Classification

The aetiology of radial club hand or radial dysplasia can be divided into "sporadic" and "syndromal" cases.

Sporadic cases are not inherited and are presumed to be due to de novo genetic mutations.

Syndromal cases; certain syndromes have a higher than expected association with radial dysplasia. Typically, organ systems are affected that develop at the same time as the upper limb:

• VACTERL association
  VACTERL association
  VATER syndrome or VACTERL association is a non-random association of birth defects. The reason it is called an association, rather than a syndrome is that while all of the birth defects are linked, it is still unknown which genes or sets of genes cause these birth defects to occur.Each child with...
  
   or VATER syndrome
• Holt-Oram syndrome
  Holt-Oram syndrome
  Holt–Oram syndrome is a disorder that affects bones in the arms and hands and may also cause heart problems.-Presentation:All people with this disorder have at least one limb abnormality that affects bones in the wrist . Often, these wrist bone abnormalities can be detected only by X-ray...
  
  
• Edwards syndrome
  Edwards syndrome
  Trisomy 18 is a genetic disorder caused by the presence of all or part of an extra 18th chromosome. It is named after John H. Edwards, who first described the syndrome in 1960...
  
  
• haematopoietic syndromes:
  • Fanconi anemia
    Fanconi anemia
    Fanconi anemia is a genetic disease with an incidence of 1 per 350,000 births, with a higher frequency in Ashkenazi Jews and Afrikaners in South Africa.FA is the result of a genetic defect in a cluster of proteins responsible for DNA repair...
    
    
  • Thrombocytopaenia with Absent Radius (TAR syndrome
    TAR syndrome
    TAR Syndrome is a rare genetic disorder that is characterized by the absence of the radius bone in the forearm, and a dramatically reduced platelet count...
    
    )
• craniofacial syndromes:
  • Nager's Syndrome
  • Goldenhar's syndrome
  • Mobius syndrome
    Mobius syndrome
    Möbius syndrome is an extremely rare congenital neurological disorder which is characterized by facial paralysis and the inability to move the eyes from side to side. Most people with Möbius syndrome are born with complete facial paralysis and cannot close their eyes or form facial expressions...
    
    
  • cleft lip and palate
  • Treacher-Collins syndrome
• skeletal syndromes and isolated skeletal associations:
  • Klippel-Feil syndrome
    Klippel-Feil syndrome
    Klippel–Feil syndrome is a rare disease, initially reported in 1912 by Maurice Klippel and André Feil from France, characterized by the congenital fusion of any 2 of the 7 cervical vertebrae....
    
    
  • Sprengel deformity
  • syndactyly
    Syndactyly
    Syndactyly is a condition wherein two or more digits are fused together. It occurs normally in some mammals, such as the siamang and kangaroo, but is an unusual condition in humans.-Classification:...
    
    
  • scoliosis
    Scoliosis
    Scoliosis is a medical condition in which a person's spine is curved from side to side. Although it is a complex three-dimensional deformity, on an X-ray, viewed from the rear, the spine of an individual with scoliosis may look more like an "S" or a "C" than a straight line...
    
    
• teratogens:
  • radiations
  • valproic acid
    Valproic acid
    Valproic acid is a chemical compound that has found clinical use as an anticonvulsant and mood-stabilizing drug, primarily in the treatment of epilepsy, bipolar disorder, and, less commonly, major depression. It is also used to treat migraine headaches and schizophrenia...
    
    
  • thalidomide
    Thalidomide
    Thalidomide was introduced as a sedative drug in the late 1950s that was typically used to cure morning sickness. In 1961, it was withdrawn due to teratogenicity and neuropathy. There is now a growing clinical interest in thalidomide, and it is introduced as an immunomodulatory agent used...