Aim: To investigate the gene mutations causing defects in thyroid organogenesis and morphogenesis in cases with thyroid dysgenesis (TD).
Methods: The presence of variations/mutations in the genes TSHR, PAX8, NKX2, FOXE1, TPO, TG, SLC26A4, SLC5A5, DUOX2, DUOXA2, IYD, TSHB, TRHR and IGSF1 was investigated in 35 cases diagnosed with TD on the basis of thyroid function tests, ultrasound, and scintigraphy at the Kocaeli University Faculty of Medicine between 2003 and 2013.
Results: Agenesis was present in 11 of the 35 patients who underwent mutation analysis, ectopia in 22, and hemiagenesis in 2. Heterozygous mutation in SCL264A was determined in 3 patients and heterozygous mutations in DUOXA2, DUOX and TSHR in one patient each. Biallelic DUOX2 mutation was detected in one patient and monoallelic probable pathological variants were detected in 6 patients. Mutation was determined in 2% of the subjects. However, there have been no previous reports of all mutations determined being heterozygous and these are probably polymorphisms.
Conclusion: TD is generally sporadic and mutations in the genes responsible for thyroid development have been shown in only a very small group of the cases.