Objective: To determine if anatomical variations in the paranasal sinuses of twins are the result of genetic or environmental influences.
Study design: A prospective, observational study.
Setting: An academic hospital in Brussels, Belgium.
Participants: Twenty-five volunteer twins (17 identical twins and eight non-identical twins). Of the identical twins, six were both female and 11 both male. The mean age was 40.6 years (18–49). Of the non-identical twins, one pair was female and seven were male. The mean age was 39.6 years (25–48).
Main outcome measures: The CT-scan similarity in anatomical structures (frontal cells, agger nasi cells, concha bullosa, infraorbital cells and changes in the shape of the lamina orbitalis), and the intranasal and paranasal sinus morphology was compared between the twins.
Results: Among the studied variables, there was no statistically significant difference between the two twin groups (Fisher's exact test, P > 0.05). Regarding combine-studied parameters, there were no identical CT scans in the twins. However, a tendency of non-genetic influence existed in the development of frontal cell type III and IV, and infraorbital cells, as well as a liability of genetic influence in the presence of concha bullosa.
Conclusion: In this study, the differences in anatomical structure of the paranasal sinuses between identical and non-identical twin pairs were not statistically significant. This indicates that environmental factors are more significant than genetic ones in the development of anatomical variations in paranasal sinus anatomy.