Brachydactyly is a hereditary disease characterized by malformation of finger(s)/toe(s). A group of German scientists reported that duplication on Chromosome 20 is associated with the condition. We have studied this disorder in a Chinese family. We found that a 4.6kb duplication, smaller than the German group reported, on Chromosome 20, appeared in all the brachydactyly patients, but is absent in the unaffected family members and in 100 unrelated normal subjects. This fragment is located downstream of BMP2, the gene that regulates bone formation. Our further study showed that the duplication could affect the expression of the gene. (by Professor Yiming Wang, http://jmg.bmj.com/content/early/2011/02/26/jmg.2010.084814.abstract?papetoc= )