We studied the role of the immunoglobulin heavy-chain allotypes in the evolution of celiac disease. Particularly the Gm(fb) phenotype was investigated since this phenotype is able to determine the breadth of immune response against alpha-gliadin antigen. The results show that weight percentiles and intestinal absorption as assessed by xylose test are influenced by Gm(fb) phenotype suggesting that Gm(fb) genes contribute to the determination of clinical aspects and evolution of celiac disease.