Lecture 10: MNS and Other Blood Groups PDF

Lecture 10: MNS and Other Blood Groups SCIE2040 MNS Blood System Antithetical M and N and antithetical S and s U- is included in the MNS system, exclusively found amongst African population S- and s- = U- Genetic inheritance similar to Rh system 2 pairs of closely linked allele...

Lecture 10: MNS and Other Blood Groups SCIE2040 MNS Blood System Antithetical M and N and antithetical S and s U- is included in the MNS system, exclusively found amongst African population S- and s- = U- Genetic inheritance similar to Rh system 2 pairs of closely linked alleles which occupy 2 closely linked loci GYPA gene controls M and N GYPB gene controls S and s Found on glycophorins transverse to the red cell membrane Glycophorin A carries M or N Glycophorin B carries S or s and U M and N have almost equal frequency s frequency is greater than S MNS Antibodies M and N Ab are mostly opposite of the S, s, U Anti-M and anti-N can usually be seen as clinically insignificant unless reactive at 37°C Not the case with anti-S and anti-s Anti-M is usually insignificant but has been rarely associated with severe HDN Effect varies by enzyme but enzymes generally decrease all MNS Ag except U Most examples of anti-M, anti-N, and anti-s do not bind complement Some examples of anti-S do bind complement Dosage is seen with anti-M and anti-N and not so noticeable with anti-S and anti-s  Clinical Significance of Abs Anti-M and anti-N relatively common antibodies but transfusion reactions are rare Anti-M seldomly clinically significant and anti-N not so clinically significant Anti-S and anti-s relatively uncommon but transfusion reactions have been reported Anti-s is more clinically significant when compared to anti-S HDN due to anti-M and anti-N are rare but HDN due to anti-S and anti-s are more common Some examples of anti-M react more strongly with M positive cells when plasma is acifified to pH of 6.5 Dialysis associated anti-N formed in patients who were dialyzed on equipment sterilized with formaldehyde Residual formaldehyde sometimes alters red cells Patient forms an autoantibody which serologically resembles anti-N Anti-N almost exclusive to the African ethnicity