Antibodies play a crucial role in eliminating infections by recognising foreign antigens with high specificity and affinity. If a target is not directly neutralised, antibodies can mediate potent effector function responses by coordinating the recruitment of immune cells through their constant regions. These powerful immune functions are being widely explored in the form of IgG-based monoclonal antibody therapies for the treatment of infections, cancer, and autoimmune diseases. However, the antibody constant region exhibits significant genetic polymorphism, and new variants are rapidly being discovered by advances in genomic sequencing techniques. The documented effects of this diversity include differences in structural dynamics, thermal stability, and Fc-mediated effector functions among a number of antibody subclasses, including IgG1, IgG2, and IgG3. Some variants are reported to be a contributing factor to variability in the outcome of disease and responsiveness to vaccines in humans. The IgG3 subclass, in particular, displays striking differences in the antibody hinge region – responsible for connecting target binding with constant-region-mediated immune function. Here, exon duplications mean the hinge region can vary by as many as 45 amino acids in length. This work seeks to better understand some of the functional consequences of this unusual IgG3 variation. To assess the effects of allelic hinge variation on protein dynamics and effector functions, we have expressed a panel of seven anti-CD20 antibodies with unique constant region allele sequences from subclasses IgG1, IgG2, and IgG3. Sequence verified plasmids were used to express full-length antibodies in HEK293 cells at high purity. We first used small angle X-ray scattering (SAXS) to assess the variability in size and structural flexibility between the allelic variants and compared our data with previous research on the same variant panel with antiHER2 variable domain sequences. Following this structural analysis, we next undertook ADCC (antibody-dependent cellular cytotoxicity) and ADCP (antibody dependent cellular phagocytosis) assays to determine if differences in structural dynamics between the polymorphic variants could be linked to differences in effector function. These assays specifically used genome-engineered reporter cell lines to evaluate the ability of allelic variants to engage constant region binding FcyRIIIa and FcyRIIa Fc receptors, typically found on peripheral blood mononuclear cells. Activation was measured by quantifying the levels of luciferase expressed as a reporter. The findings provided in this study demonstrate that allelic variants with longer hinges have larger and more flexible structures and tend to present weaker ADCC and ADCP responses. The data presented here is the basis for future work on the influence of IgG constant region diversity on antibody structural dynamics and effector functions, which could contribute to improvements in the design of therapeutic antibodies.