Thyroid abnormalities such as (subclinical) hypothyroidism, antithyroglobulin, and thyroid peroxidase antibodies, (euthyroid) Hashimoto thyroiditis, and increased frequency of thyroid cancer as long-term sequela is not restricted to TBI-based conditioning regimen only and affect HSCT survivors with a total frequency in the range of 20% - 35% (75–79). This evidence concerns the gene TPO and thyroiditis.