A previously unidentified abnormal human chromosome which is believed to have caused Down's syndrome has been found in a girl and her mother in the Guangxi Zhuang Autonomous Region, south China.

Li Xinle, associate professor with Youjiang Ethnic Medical Institute, said the chromosome was found in a one-year-old Down's syndrome girl and her mother during a genetic test conducted August last year.

According to Li, both mother and daughter demonstrate a transposal of No. 2 and No. 10 chromosomes. The baby girl also carries an additional No. 21 chromosome, which is believed to be the cause of the girl's handicap.

The China National Medical Genetics Laboratory confirmed that no identical chromosome has ever been reported after consulting the international abnormal human chromosome database and relevant documents, Li said.

The finding will contribute to world medical and genetic research and help prevent future cases of the disease, said Dai Heping of the state key medical genetics laboratory.

(Xinhua News Agency March 30, 2002)