Bisalbuminemia: A Pathologist's Insight of an Uncommon Phenomenon

Background The incidence of a bifid electrophoretic pattern in the albumin region on serum protein electrophoresis is an infrequent phenomenon. The availability of literature from India is scarce and is limited to case reports. Objective The aim of the study is to analyze the frequency of bisalbuminemia in an Indian referral facility. The study delved into their clinical associations. Material and Methods The retrospective case records of the patient from the departmental database were scrutinized. The study subjects were for an 8-year study period. Results There were about 39,900 serum electrophoresis performed in an 8-year study period. A total of 40 cases of bisalbuminemia were detected. The incidence in our cohort was 0.01%. Conclusion Bisalbuminemia, an overtly benign condition, is infrequent in Indian population although not rare. It is associated with several clinical disorders; however, the association seems to be plausibly coincidental.

Human serum albumin isoforms: genetic and molecular aspects and functional consequences

BACKGROUND

At present, 67 different genetic variants of human serum albumin and proalbumin have been molecularly characterized at the protein and/or gene level.

SCOPE OF REVIEW

This review summarizes present knowledge about genetic and molecular aspects, functional consequences and potential uses of the variants.

MAJOR CONCLUSIONS

The frequency of bisalbuminemia in the general population is probably about 1:1000, but it can be much higher in isolated populations. Mutations are often due to hypermutable CpG dinucleotides, and in addition to single-amino acid substitutions, glycosylated variants and C-terminally modified alloalbumins have been found. Some mutants show altered stability in vivo and/or in vitro. High-affinity binding of Ni(++) and Cu(++) is blocked, or almost so, by amino acid changes at the N-terminus. In contrast, substitution of Leu90 and Arg242 leads to strong binding of triiodothyronine and l-thyroxine, respectively, resulting in two clinically important syndromes. Variants often have modified plasma half-lives and organ uptakes when studied in mice.

GENERAL SIGNIFICANCE

Because alloalbumins do not seem to be associated with disease, they can be used as markers of migration and provide a model for study of neutral molecular evolution. They can also give valuable molecular information about albumins binding sites, antioxidant and enzymatic properties, as well as stability. Mutants with increased affinity for endogenous or exogenous ligands could be therapeutically relevant as antidotes, both for in vivo and extracorporeal treatment. Variants with modified biodistribution could be used for drug targeting. In most cases, the desired function can be further elaborated by producing site-directed, recombinant mutants. This article is part of a Special Issue entitled Serum Albumin.