The strengths and limitations of the study
The main strength of the present study is that, for the first time, the
subjects were genotyped by a molecular method. In previous studies,
either the genotypes were estimated based on the phenotype of parents,
or only the effects of Rh phenotypes, not Rh genotypes, were studied.
Another important advantage is that the Rh phenotypes/genotypes were
estimated in the course of a study and not self-reported by the
participants of the study.
The main limitation of the study is that subjects reported their health
problems themselves. It is clear that some people might misreport their
health problems. However, there is no reason to expect that Rh-positive
heterozygotes and homozygotes (mis)reported their problems differently
unless they really differ in their health status. It is important to
remember that participants were not aware of their RhD genotype at the
time of filling the questionnaire. Another limitation of the present
study is that participants have been self-selected and therefore
probably do not represent a typical Czech population. The observed
higher prevalence of Rh-negative subjects among the participants (24.2
% in women and 27.2 % in men) than in the general Czech population (16
%) (a phenomenon reported also in all previous Czech studies on
volunteers, reviewed in (Flegr, Toman, et
al., 2020)) suggests that Rh-negative subjects have a higher
willingness to participate in unpaid scientific studies.