Cancers of the thyroid gland can be divided into medullary thyroid cancers (MTC, derived from calcitonin-producing C cells) and nonmedullary thyroid cancers (NMTC, derived from follicular cells). Papillary cancers make up 85% of NMTCs, while the remaining are follicular or Hurthe cell cancers.   NMTC5 is a nonmedullary cancer that runs in families.  Symptoms of thyroid cancer include a painless lump in the neck, hoarseness of the voice, trouble swallowing, and a sore throat.  NMTC is found to affect women more often than men.  While it can occur at any age, the disease commonly presents itself in adults around the third or fourth decade of life. 

For a definite diagnosis of thyroid cancer, a fine needle aspiration biopsy of the thyroid cells is usually carried out; thereby allowing pathologists to determine the exact type of cancer involved.  Treatment involves a surgical thyroidectomy to remove the cancerous thyroid cells.  This is followed by radioactive iodine treatment, a targeted chemotherapy approach that kills any remaining thyroid cells.  Patients also require life-long thyroid hormone replacement.  The drug levothyroxine is administered for this purpose.  Prognosis of the disorder depends on the age and severity of the disease.  However, compared to other types of thyroid cancer, NMTC is considered to be less aggressive and has a 97% cure rate. 

NMTC5 follows an autosomal dominant pattern of inheritance.  It is believed to be caused by heterozygous mutations in the HABP2 gene.  This gene encodes a serine protease that is speculated to act as a tumor suppressor.  So far, only one variant; G534E (missense mutation), located within the serine-protease-trypsin domain of the HABP2 protein, has been linked to NMTC5.  The mutation is predicted to cause a space constraint near the catalytic region, disrupting the active site and surface accessibility of its substrates.