Which of the following is true about isotypic variation?

Ans (c) Changes in heavy and light chain in constant region responsible for class and subtype Ref. Ananthanarayan 8/e, p /01; DR Arora 3/e p 119 Isotopic specificities The antigenic specificities which distinguish between the different classes and subclasses of immunoglobulin present in all individual of a species,. e.g. Antigen specificity of IgA and IgG. They are located on (Constant) domains of Ig chains in all individual. Other immunoglobulin Specificity Idiotypic specificity - Specificity of greatest biological impoance is idiotypic specificity, peaining to the nature of antigen binding site. These are located on V region. Allotypic-specificity - Antigenic specificity which distinguishes immunoglobulins of the same class, between different groups of individual in the same species.