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A3 phenotype with A1 gene-specified enzyme character in serum
I Nakamura1, H Takizawa, K Nishino
1Department of Legal Medicine, Faculty of Medicine, Toyama Medical and Pharmaceutical University, Japan.
Experimental and Clinical Immunogenetics
|January 1, 1989
Summary
Researchers identified an active A enzyme in A3 blood group serum, similar to A1 enzyme properties. Weak A enzyme activity in red blood cells suggests suppressed production in hemopoietic tissues for this rare A3 phenotype.
Area of Science:
- Biochemistry
- Immunology
- Genetics
Background:
- The A3 phenotype is a rare blood group characterized by specific red blood cell agglutination patterns.
- Understanding the underlying enzymatic and genetic basis of rare blood groups is crucial for transfusion medicine and population genetics.
Purpose of the Study:
- To investigate the biochemical properties of the A enzyme in individuals with the A3 phenotype.
- To determine the cause of weak A expression in the A3 phenotype, specifically in hemopoietic tissues.
Main Methods:
- Enzyme activity assays were performed on serum and red blood cell membranes.
- Biochemical parameters including pH optimum, Km, Vmax, and heat stability were analyzed.
- Agglutination tests were used to assess red cell membrane properties.
Main Results:
- An active A enzyme was detected in the serum of A3 phenotype individuals.
- The enzyme's kinetic and stability properties were comparable to the A1 gene-specified enzyme.
- Weak A enzyme activity was observed in anti-A agglutinable red cell membranes, but not in unagglutinable ones.
- The A3 phenotype exhibited a high frequency in the Toyama district (approx. 0.00086).
Conclusions:
- The weak A expression in the A3 phenotype is likely due to suppressed A enzyme production specifically within hemopoietic tissues.
- This finding provides insight into the molecular mechanisms underlying rare blood group expression and distribution.