This is the first time such a disease has been discovered, and it has been named "He-Zhao-Deficiency" after its Chinese discoverers and scientists.

　　The name is now being used among world medical communities. Online Mendelian Inheritance In Man, a prestigious international medical archive, has included the disease in its index.

　　He Lin, director of BIO-X Life Sciences Research Center with the Shanghai Jiaotong University, says the pathogenic gene lies inthe long arm of the 10th chromosome of a human.

　　He made the discovery together with scientists at the Shanghai Life Research Center affiliated to China's Academy of Sciences, the Shanghai Human Gene Research Center as well as the BIO-X Center.

　　The research group has published their findings in a most prestigious American dental magazine.

　　Zhao Wanli, a doctor in northwest China's Shaanxi Province, together with his cousin, Zhao Shuangmin, at the end of the 1990s,found six generations of one local family who were all toothless.

　　Zhao Shouyuan, a professor with Fudan University and an authority in genetics, says the discovery and the finding of its genetic cause are a breakthrough in China's genetic research for hereditary diseases.

　　Statistics show that worldwide 9.6 percent of people suffer from different kinds of dental diseases.