An Immunologic Investigation of Bisalbuminemia : A Genetically Transmitted Serum Protein Anomaly

Abstract

The problem. Bisalbuminemia was investigated in an Iowa family by testing for hematological and immunologic abnormalities to determine associations between bisalbuminemia and connective tissue (collagen) and/or autoimmune diseases. Physiochemical properties of the anomalous albumin fraction were compared to normal serum albumin. Procedure. Cellulose acetate electrophoresis was used to determine the genotypes from which was established the genetic pedigree of the bisalbumin trait. Sera of family members was screened using the following tests: Complete blood count; sedimentation rate; hematocrit; antistreptolysin 0 titer; rheumatoid factor; LE preparation; VDRL; C-reactive protein and fluorescent anti-nuclear antibody analysis. Physiochemical characterization of the anomalous albumin fraction included an agar-gel diffusion study and measurement of the relative binding ability of normal and abnornal albumins using I125-thyroxine. Findings. Bisalbuminemia was found in seven of fourteen members of an Iowa family and was presumed to have been present in one deceased member of the family. The anomaly, transmitted as an autosomal codominant, was observed in the heterozygous state. The anomalous albumin fraction, albumin B, replaces one-half of the normal serum albumin and was found to be an albumin by agar-gel diffusion. Tests commonly associated with connective tissue and autoimmune diseases failed to show a relationship between the disease groups and bisalbuminemia. Addition of I125-thyroxine to bisalbumin sera resulted in excess thyroxine binding to albumin B with greater affinity than to normal albumin. Conclusions. The anomalous albumin B is assumed to be the result of a mutation of a gene responsible for the synthesis of normal serum albumin. The bisalbuminemia analyzed in this family study does not appear to be associated with the connective tissue and/or autoimmune diseases or any marked clinical abnormalities.