JMH blood group system: a review.

Area of Science:

• Immunology
• Genetics
• Hematology

Background:

• The JMH blood group system comprises six high-prevalence antigens.
• These antigens are associated with the Sema7A protein, encoded by the SEMA7A gene on chromosome 15.
• JMH1, also known as JMH, is characterized by transient antigen depression and potential anti-JMH antibody development.

Purpose of the Study:

• To provide a comprehensive overview of the JMH blood group system.
• To detail the serologic and molecular characteristics of JMH antigens.
• To discuss the proposed functions of the Sema7A protein in relation to the JMH system.

Main Methods:

• Review of existing literature on the JMH blood group system.
• Analysis of serologic data related to JMH antigen expression and antibody formation.
• Examination of molecular genetic data, including single nucleotide changes in the SEMA7A gene.

Main Results:

• The molecular basis for the JMH1- phenotype remains undetermined.
• Single nucleotide changes in the SEMA7A gene are responsible for other JMH antigens.
• Anti-JMH antibodies are common but typically insignificant in transfusions, whereas antibodies in rare JMH variants can reduce red cell survival.

Conclusions:

• The JMH blood group system presents unique serologic and molecular features.
• Understanding the SEMA7A gene's role is crucial for characterizing JMH antigens.
• Rare JMH variants pose potential transfusion risks due to antibody-mediated red cell destruction.