Description: The monoclonal antibody 6A7M recognizes human glycophorin A (also known as CD235a). The antibody reacts with the M allele. Glycophorin A is a 151 amino acid sialoglycoprotein found on the erythrocyte (RBC) and erthyroid progenitor cell membrane at about 500,000 copies per cell. The gene for glycophorin resides on chromosome 4 and has 2 allelic forms: M and N, which differ in two amino acids. The M group possesses Ser1 and Gly5 while the N group has Leu1 and Glu5. Recent data suggest that exposure to toxins can cause mutation or loss of an allele resulting in phenotypic changes. Studies are also beginning to correlate genotype/phenotype with predisposition to cancer and heart disease.