Thyroid 1

Question 1

What is Pendrin Syndrome?

Answer 1

• Genetics: AR mutation in SLC26A4, which makes PDS which pushes I- through the apical membrane. This step is essential for iodine organification.
• Phenotype: Goiter + sensorineural deafness + congenital hypothyroidism.

Question 2

What is the most common cause of thyroid DYShormonogenesis?

Answer 2

• Genetics: AR defects in TPO from 2p25, so cannot perform organification.
• Phenotype: Neonates with goiter.

Question 3

What is the significance of an SLC5A5 mutation?

Answer 3

• SLC5A5 encodes the Na/I- symporter and is necessary for iodine trapping in thyroid follicular cells.
• SLC5A5 mutations will cause congenital hypothyroidism.

Question 4

Summarize PAX8 mutations.

Answer 4

• Genetics: AD mutation in PAX8 on 2q14.
• Phenotype: Half a thyroid and missing 1 kidney.