The role of mutagenic factors in the onset of diffuse toxic goiter (DT
G) was studied in 49 families of probands with DTG. The evidence obtai
ned on the order in which the child was born in the proband's family,
age of the parents at the time of DTG child delivery, implications of
occupational factors in DTG onset does not rule out mutagenic effects
in the origin of DTG and thus feasibility of the key gene influence on
the disease predisposition.