Serum proteomics for the diagnosis of nephrotic syndrome: is there a ray of hope?

The term proteomics came into use only about 15 years ago1. Proteomics is the systematic analysis of proteins and peptides in a biological sample. It has been the natural offshoot of the Human Genome Project. A proteome is a list of all expressed proteins in the sample of interest. While genomics links gene activity with disease, proteomics investigates gene expression i.e. the proteins which are the ultimate effector molecules; and hence more relevant to identification of biomarkers. It is the simultaneous study of multiple proteins rather than one protein at a time as in traditional biochemistry2. Proteomics is capable of characterizing several thousand proteins in a single analysis. It has been used for better understanding of renal physiology and pathophysiology of renal diseases1. In clinical nephrology proteomics is a tool to identify biomarkers. The development of a biomarker essentially has three steps: biomarker discovery, validation and ultimately implementation3. Biomarkers are useful for early non-invasive diagnosis of disease, monitoring disease progression and prediction of drug efficacy4. A major advantage of the proteomic approach is its unbiased nature3, and the major disadvantage is that biomarker studies are always underpowered since the number of samples required should exceed the number of observations3. The basic steps of proteomics include (i) albumin removal; (ii) proteins digestion; (iii) protein separation step; and (iv) analysis by mass spectrometry2,5–7.