Congenital radio-ulnar synostosis is a rare condition in which there is an abnormal connection (synostosis) of the radius and ulna (bones in the forearm) at birth. The condition is present in both arms (bilateral) in approximately 60% of cases. Signs and symptoms depend on the severity of the abnormality and whether it is bilateral; affected individuals often have limited rotational movement of the forearm. Pain is usually not present until the teenage years. It is due to abnormal fetal development of the forearm bones, but the underlying cause is not always known. It is sometimes a feature of certain chromosome abnormalities or genetic syndromes. Some cases appear to be inherited in an autosomal dominant manner. Treatment may be conservative or involve surgery depending on the severity of the abnormality and the range of movement.
Last updated: 9/24/2012
What causes congenital radio-ulnar synostosis?
Congenital radio-ulnar synostosis is caused by abnormal development of the forearm bones in the fetal period, although the underlying cause of the developmental abnormality is not always known. The condition may be isolated (occur without other abnormalities) or it may be associated with various other skeletal, cardiac (heart), neurologic, or gastrointestinal abnormalities. When other abnormalities are present, the condition may be due to an underlying genetic cause, including a variety of syndromes or chromosome abnormalities.
How is congenital radio-ulnar synostosis inherited?
Congenital radio-ulnar synostosis appears to be inherited in an autosomal dominant manner in some cases. This means that one mutated copy of the disease-causing gene in each cell is sufficient to cause the condition. The mutated gene may occur for the first time in an affected individual, or it may be inherited from an affected parent. Each child of an individual with an autosomal dominant condition has a 50% (1 in 2) risk to inherit the mutated copy of the gene.