Lewis blood group was used historically to find secretor or non-secretor status in subjects who are not 'Lewis negative', and correlates with the saliva secretor inhibition test. Lewis blood group antigens are not true cell surface antigens, but adhere to the surface of the red blood cells by adsorption, and can become detached from the cell with increasing age of the sample. Where we get a Lewis negative result from a sample that is several days old we ask for a repeat sample before reporting Lewis negative, to make sure that the results are accurate.
Our haematology laboratory is operated by a qualified laboratory technician experienced in using reagents for blood group serology. We always use a control sample to check the reagents are functioning correctly.
In terms of the correlation between genome test results and secretor status from Lewis testing we have found an exact match with the results of the SNP for FUT2.