[Alpha heavy chain disease. Molecular analysis of a new case]

The NH2-terminal structure of serum abnormal protein, as well as the sequence of the corresponding mRNA, were determined in a new case of alpha heavy chain disease. The patient presented with typical clinical features of the disease. Intestinal and mesenteric lymphoplasmic infiltration was monoclonal as assessed by the study of the configuration of heavy and light chain genes. The serum abnormal alpha chains included two molecular species: one starting at the beginning of the hinge region and the other being two amino acids shorter, missing the two first amino acids of the hinge region. The sequence of the mRNA displayed a leader exon, a 93 bp sequence of unknown origin and the second and third constant exons of human alpha 1 chain. These data are discussed in the light of previously reported molecular studies in heavy chain diseases.