Routine phenotyping of native and desialyzed alpha 2HS-glycoprotein from blood stains

The application of a polyacrylamide gel isoelectric focusing (PAGIEF) and immunoblotting procedure for the identification of native alpha 2HS-glycoprotein (AHSG) in routine casework blood stains has produced reportable results on 57.2% of samples. This reporting rate is lower than that for group specific component (GC) (83.8%) and phosphoglucomutase (PGM 1) (72.8%) phenotyping of the same samples. Blood stain samples were desialyzed with 1 U/ml neuraminidase, overnight at room temperature prior to PAGIEF in gels containing pharmalyte pH 5-6 and 2.5 M urea. Simple AHSG patterns were developed by immunoblotting. This procedure was five times as sensitive as the native AHSG method and desialyzation was reproducible over a range of incubation times and neuraminidase concentrations. The application of the desialyzed AHSG analysis to routine casework samples has resulted in a significant increase in the number of reportable results (762 reported out of 1027 samples). This reporting rate (74.2%) compares favourably with that for GC (79.1%) and PGH 1 (69.6%) phenotyping of the same samples. The three AHSG alleles (AHSG*1, 2 and 3) are clearly resolved after sample desialyzation and separation in gels containing pharmalyte pH 5-6 and 2.5 M urea. The sensitivity of desialyzed AHSG phenotyping approaches that of GC and this technique is worthy of inclusion in blood stain screening protocols of forensic laboratories in regions where the population has a limited range of rare AHSG alleles.