Familial forms of TD including hemithyroid. A history of TD in at least one relative was found in nine patients belonging to the eight multiplex families shown in this figure. In seven of these eight families, a single relative was known to have TD, whereas in the remaining family (F5), three first-degree relatives were affected. Thyroid abnormalities in these families consisted of THG only (n = 1), THG with ectopy (n = 4), THG with athyreosis (n = 1), or THG with thyroglossal duct cysts (n = 2). The affected first-degree relatives were siblings in eight of these nine patients; in the remaining case, an aunt and her niece were affected. Ureterovesical malformations were found in only one family (number 1), in both members with TD. ▪ thyroid hemiagenesi, athyréosis, • ectopic thyroid gland, □ thyroglossal duct cysts.