Duane-radial ray syndrome
Encyclopedia
Duane-radial ray syndrome is a rare disorder that affects the eye
s and causes abnormalities of bones in the arms and hands.
People with the combination of Duane anomaly and radial ray malformations may have a variety of other signs and symptoms. These features include unusually shaped ears, hearing loss, heart and kidney defects, a distinctive facial appearance, an inward- and downward-turning foot (a clubfoot), and fused vertebrae.
gene cause Duane-radial ray syndrome. The SALL4 gene is part of a group of genes called the SALL family. These genes provide instructions for making proteins that are involved in the formation of tissues and organs before birth. SALL proteins act as transcription factor
s, which means they bind to specific regions of DNA
and help control the activity of particular genes. Mutations in the SALL4 gene prevent one copy of the gene in each cell from making any protein. It remains unclear how a reduction in the amount of SALL4 protein leads to Duane anomaly, radial ray malformations, and the other features of Duane-radial ray syndrome and similar conditions. Duane-radial ray syndrome often is inherited in an autosomal dominant pattern, which means one copy of the altered gene in each cell is sufficient to cause the disorder.
Human eye
The human eye is an organ which reacts to light for several purposes. As a conscious sense organ, the eye allows vision. Rod and cone cells in the retina allow conscious light perception and vision including color differentiation and the perception of depth...
s and causes abnormalities of bones in the arms and hands.
Presentation
The name of the condition refers to the two elements which most commonly present:- This condition is characterized by a particular problem with eye movement called Duane anomaly (also known as Duane syndrome). Duane anomaly results from the improper development of certain nerveNerveA peripheral nerve, or simply nerve, is an enclosed, cable-like bundle of peripheral axons . A nerve provides a common pathway for the electrochemical nerve impulses that are transmitted along each of the axons. Nerves are found only in the peripheral nervous system...
s that control eye movement. This condition limits outward eye movement (toward the ear), and in some cases may limit inward eye movement (toward the nose). As the eye moves inward, the eye opening becomes narrower and the eyeball may pull back (retract) into its socket.
- Bone abnormalities in the hands include malformed or absent thumbThumbThe thumb is the first digit of the hand. When a person is standing in the medical anatomical position , the thumb is the lateral-most digit...
s, an extra thumb, or a thumb that looks like a finger. Partial or complete absence of bones in the forearm is also common. Together, these hand and arm abnormalities are called radial ray malformations.
People with the combination of Duane anomaly and radial ray malformations may have a variety of other signs and symptoms. These features include unusually shaped ears, hearing loss, heart and kidney defects, a distinctive facial appearance, an inward- and downward-turning foot (a clubfoot), and fused vertebrae.
Related conditions
The varied signs and symptoms of Duane-radial ray syndrome often overlap with features of other disorders.- For example, acro-renal-ocular syndrome is characterized by Duane anomaly and other eye abnormalities, radial ray malformations, and kidney defects. Both conditions can be caused by mutations in the same gene. Based on these similarities, researchers are investigating whether Duane-radial ray syndrome and acro-renal-ocular syndrome are separate disorders or part of a single syndrome with many possible signs and symptoms.
- The features of Duane-radial ray syndrome also overlap with those of a condition called Holt-Oram syndromeHolt-Oram syndromeHolt–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...
; however, these two disorders are caused by mutations in different genes.
Genetics
Mutations in the SALL4SALL4
Sal-like protein 4 is a protein that in humans is encoded by the SALL4 gene.It can be associated with Duane-radial ray syndrome.-External links:*-Further reading:...
gene cause Duane-radial ray syndrome. The SALL4 gene is part of a group of genes called the SALL family. These genes provide instructions for making proteins that are involved in the formation of tissues and organs before birth. SALL proteins act as transcription factor
Transcription factor
In molecular biology and genetics, a transcription factor is a protein that binds to specific DNA sequences, thereby controlling the flow of genetic information from DNA to mRNA...
s, which means they bind to specific regions of DNA
DNA
Deoxyribonucleic acid is a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms . The DNA segments that carry this genetic information are called genes, but other DNA sequences have structural purposes, or are involved in...
and help control the activity of particular genes. Mutations in the SALL4 gene prevent one copy of the gene in each cell from making any protein. It remains unclear how a reduction in the amount of SALL4 protein leads to Duane anomaly, radial ray malformations, and the other features of Duane-radial ray syndrome and similar conditions. Duane-radial ray syndrome often is inherited in an autosomal dominant pattern, which means one copy of the altered gene in each cell is sufficient to cause the disorder.