Based on what I learned in medical school, my guess would be iodine deficiency. https://en.wikipedia.org/wiki/Congenital_iodine_deficiency_syndrome https://en.

Based on what I learned in medical school, my guess would be iodine deficiency. https://en.wikipedia.org/wiki/Congenital_iodine_deficiency_syndrome https://en.wikipedia.org/wiki/Congenital_iodine_deficiency_s... Iodine is vitally important for child development, especially brain development. In mountainous regions, there can be less iodine in the soil (and you are away from the ocean where fish and other seafood are a ready source of iodine). IIRC, it used to be a big issue in the Alpine regions of Europe. This is one of the reasons that iodine is put into salt as a supplement.