domingo, 14 de abril de 2013

Poland syndrome - Genetics Home Reference

Poland syndrome - Genetics Home Reference

Genetics Home Reference: your guide to understanding genetic conditions

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Poland syndrome

Reviewed March 2013

What is Poland syndrome?

Poland syndrome is a disorder in which affected individuals are born with missing or abnormal muscles on one side of the chest wall. Most individuals with Poland syndrome also have abnormalities of the hand, which often involve shortened fingers, partial fusion of the fingers, or both. The hand abnormalities usually affect the same (ipsilateral) side of the body as those of the chest. Poland syndrome affects the right side of the body more often than the left side.
People with Poland syndrome are missing part of one of the major chest muscles, called the pectoralis major. In most affected individuals, the missing part is the large section of the muscle that normally attaches to the upper arm on one side and the breastbone (sternum) on the other. Other abnormalities may occur on the affected side of the torso. In some cases, additional muscles in the chest wall, side, and shoulder are missing or underdeveloped. There may also be rib cage abnormalities, such as shortened ribs, and the ribs may be noticeable due to less fat under the skin (subcutaneous fat). Breast and nipple abnormalities may also occur, and underarm (axillary) hair is sometimes sparse or abnormally placed. In most cases, the abnormalities in the chest area do not cause health problems or affect movement.
Many people with Poland syndrome have hand abnormalities, commonly including an underdeveloped hand with abnormally short fingers (brachydactyly); small, underdeveloped (vestigial) fingers; and some fingers that are fused together (syndactyly). This combination of hand abnormalities is called symbrachydactyly. Some affected individuals have only one or two of these features, or have a mild hand abnormality that is hardly noticeable. The bones of the forearm (radius and ulna) are also shortened in some people with Poland syndrome, but this shortening may also be difficult to detect unless measured. Depending on their severity, hand and finger abnormalities may cause problems with use of the hand.
Mild cases of Poland syndrome without hand involvement may not be evident until puberty, when the differences (asymmetry) between the two sides of the chest become more apparent. By contrast, severely affected individuals have abnormalities of the chest, hand, or both that are apparent at birth. In rare cases, severely affected individuals have abnormalities of internal organs such as a lung or a kidney, or the heart is abnormally located in the right side of the chest (dextrocardia).
Rarely, chest and hand abnormalities resembling those of Poland syndrome occur on both sides of the body, but researchers disagree as to whether this condition is a variant of Poland syndrome or a different disorder.

How common is Poland syndrome?

Poland syndrome has been estimated to occur in 1 to 3 per 100,000 newborns. For unknown reasons, this disorder occurs more than twice as often in males than in females. Poland syndrome may be underdiagnosed because mild cases without hand involvement may never come to medical attention.

What genes are related to Poland syndrome?

The cause of Poland syndrome is unknown. Researchers have suggested that it may result from a disruption of blood flow during development before birth. This disruption is thought to occur at about the sixth week of embryonic development and affect blood vessels that will become the subclavian and vertebral arteries. These arteries normally supply blood to embryonic tissues that give rise to the chest wall and hand. Variations in the site and extent of the disruption may explain the range of signs and symptoms that occur in Poland syndrome. Abnormality of an embryonic structure called the apical ectodermal ridge, which helps direct early limb development, may also be involved in this disorder.
Rare cases of Poland syndrome are thought to be caused by a genetic change that can be passed down in families, but no related genes have been identified.

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