The clinical, biochemical, and radiological imaging characteristics were similar in both patients and included growth failure, absence of clinical goiter, markedly elevated TSH concentrations >100 mIU/L, undetectable free thyroxine levels, “normal” thyroglobulin levels, high follicle-stimulating hormone (FSH) and prolactin levels, prepubertal levels of luteinizing hormone (LH), delayed bone age, and hyperplasia of the pituitary gland. Here, PLOD1 is linked to goiter.