IT HAS been well established that there is a strong hereditary tendency in retinoblastoma. Although the exact way in which the disease is transmitted has not been agreed on, evidence largely points to its being a dominant trait irregular in type. Some cases have been reported of collateral involvement in siblings whose parents were apparently normal, and many cases of direct transmission from parent to child.
There remains, however, the majority of cases in which the appearance of the neoplasm seems to be sporadic, no relative of the child having had the disease and the parents both having normal eyes. This sporadic type may be a somatic mutation arising from a developmental disturbance, but it must be borne in mind that should such a case be arrested the patient might well found a fraternity in which the growth would become a dominant trait.
Two questions of genetic interest in relation