Mr. jansen lived in wisconsin and had an enlarged thyroid gland, or endemic due to a deficiency of in the diet, common among peoples in his geographic region of the state.

Goiter/Hypothyroidism ║Iodine

Explanation:

Goiter is the swelling of the thyroid gland due to a lack of Iodine in the diet, it is common in people that live in rural areas, mostly in mountain regions, that don't have access to iodine-rich foods in their diet. Nowadays is not that common, since table salt is enriched with iodine.