Alterations in TSC1 gene were noted in three patients: a patient with anaplastic thyroid cancer who harbored a nonsense mutation in TSC1 (p.Trp103*) and a renal cell carcinoma patient with a TSC1 splicing variant (c.1029+1G>A). Here, TSC1 is linked to thyroid gland undifferentiated (anaplastic) carcinoma.