The Lewis blood group system among Chinese in Taiwan.

The nonsecretor gene se is absent (or very rare) among Chinese in Taiwan and the previously reported Le(a+b-) phenotype in this population is in fact Le(a+b+) as proven by the presence of small amounts of Leb antigen on red blood cells. Salivary ABH substances in this phenotype are usually (although not always) markedly reduced. The Chinese Le(a+b+) phenotype is postulated to be the result of a weak secretor gene Se omega. Although the Le(a+b+) phenotype is very rare in Caucasians, it has a frequency of 25% in Chinese. All Le(a-b-) Chinese are ABH secretors and have varying amounts of Lea and/or Leb substances in saliva.