Studies in which all diagnostic data about family members are obtained from one or two informants are referred to as family history studies. Prior to 1987, all studies of the familiality of OC illness and/or OC features relied on family history data. It has been shown that, in general, family history data yields underestimates of the true rates of illness within families.42-43 Hence, it is significant that these early family history studies reported findings suggesting that OC illness and/or OC features were familial (Table II). An important shortcoming of all of these early studies was that no control samples were obtained to estimate the rate of OC illness or OC features in the general population. Thus, all of these data need to be interpreted with that caveat in mind.
