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Molecular characterization of Gm(n+) and G2m(n-) allotypes
A Brusco1, G G de Lange, C Boccazzi
1Dipartimento di Genetica, Biologia e Chimica Medica, and Centro CNR CIOS, Via Santena 19, 10 126 Torino, Italy.
Immunogenetics
|January 1, 1995
Summary
Molecular typing of Immunoglobulin (Ig) G2 gene variants G2m(n+) and G2m(n-) identified three specific DNA substitutions. These findings correlate with serological typing, establishing a molecular basis for Ig allotyping.
Area of Science:
- Immunogenetics
- Molecular Biology
- Serology
Background:
- Immunoglobulin (Ig) allotype typing traditionally relies on serological methods like hemagglutination inhibition.
- Advancements in molecular techniques enable more precise typing of Ig markers.
Purpose of the Study:
- To establish the molecular basis distinguishing G2m(n+) and G2m(n-) immunoglobulin allotypes.
- To correlate molecular typing results with established serological methods.
Main Methods:
- Amplification and cloning of G2 gene hinge, CH2, and CH3 domains from individuals with known G2m(n+) and G2m(n-) phenotypes.
- Sequence comparison to identify genetic differences between alleles.
- Molecular typing using polymerase chain reaction (PCR) with Nla III digestion and acrylamide electrophoresis for position 282; dot-blot hybridization with allele-specific oligonucleotides for positions 308 and 437.
Main Results:
- Three sequence variations were identified: two silent exonic substitutions (codons 308, 437) and one amino acid substitution at position 282 (Valine in G2m(n-) vs. Methionine in G2m(n+)).
- Molecular typing results precisely matched serological typing outcomes.
- The three identified substitutions are in strict linkage disequilibrium, consistently defining the G2m(n+) and G2m(n-) alleles.
Conclusions:
- Molecular analysis provides a definitive basis for G2m(n+) and G2m(n-) allotype discrimination.
- The developed molecular methods offer an accurate alternative to traditional serological typing for these Ig markers.
- Strict linkage disequilibrium of the identified substitutions simplifies molecular allotyping.