Extended Type I glycosphingolipid is a cell surface molecule that may be associated with, for example, certain malignant states. Aberrant glycosylation has been observed to be a common feature of many cancer types. Some of the carbohydrate antigens used for the diagnosis of human cancers carry polylactosamine structures. Polylactosamines are usually classified into two categories according to the unit structure. A polylactosamine having the Ga1β1→3G1cNAc structure is called a Type I chain, and that having the Ga1β1→4G1cNAc structure is referred to as a Type II chain. The most common tumor-associated antigens found in some human cancers have the lacto series Type II chain structure, which usually is sialylated and/or fucosylated. Type I chain antigens are abundant in normal cells and tissues, and occasionally are associated with cancer.