– PAX8 gene is a member of the paired box (PAX) family of transcription factors. Members of this gene family typically encode proteins that contain a paired box domain, an octapeptide, and a paired-type homeodomain. PAX8 is involved in thyroid follicular cell development and expression of thyroid-specific genes. Also functions in very early stages of kidney organogenesis. Mutations in PAX8 gene have been associated with thyroid dysgenesis, thyroid follicular carcinomas and atypical follicular thyroid adenomas. Alternate transcriptional splice variants, encoding different isoforms, have been characterized.