MNS blood group system: a review

Area of Science:

• Immunology and Transfusion Medicine
• Genetics and Molecular Biology

Background:

• The MNS blood group system is the second most complex after Rh, with antigens located on glycophorin A (GPA) and glycophorin B (GPB).
• While most MNS alloantibodies are not clinically significant, some can cause hemolytic disease of the fetus and newborn (HDFN).
• MNS antigens are fully developed at birth, making them relevant for neonatal care.

Purpose of the Study:

• To review key aspects of the MNS blood group system.
• To summarize the molecular basis of selected MNS antigens.
• To provide an updated overview for researchers and clinicians in transfusion medicine.

Main Methods:

• Literature review of existing studies and reviews on the MNS blood group system.
• Synthesis of information regarding antigen structure, genetic basis, and clinical significance.
• Focus on molecular mechanisms, including gene mutations and recombination events.

Main Results:

• MNS antigens are expressed on GPA, GPB, or their hybrid forms, resulting from genetic variations.
• Specific MNS antibodies, particularly those against low-prevalence or high-prevalence antigens, are associated with HDFN.
• The molecular underpinnings of MNS antigen diversity are explained through genetic processes like nucleotide substitution and unequal crossing over.

Conclusions:

• The MNS blood group system's complexity stems from its genetic origins and antigen expression.
• Understanding the molecular basis of MNS antigens is essential for accurate blood typing and managing transfusion-related complications.
• This review consolidates current knowledge, highlighting the clinical relevance of MNS system variations.