FOXE1 Polyalanine Tract Length Polymorphism in Patients with Thyroid Hemiagenesis and Subjects with Normal Thyroid

Background/Aims: Recent studies have pointed to the correlation between FOXE1 polyalanine tract (FOXE1-polyAla) length polymorphism and genetic susceptibility to thyroid dysgenesis causing congenital hypothyroidism. The objective of this study was a first assessment of the role of FOXE1-polyAla expansion in the genetic background of thyroid hemiagenesis (TH). Methods: The group studied consisted of 40 patients with TH, including 6 familial cases and a control group of 89 subjects with a normal thyroid. The polyAla tract and flanking sequence of FOXE1 was amplified using conventional PCR. Subsequently, capillary electrophoresis was performed to estimate the length of products. Results: A short variant of FOXE1-polyAla, containing 12 alanines, was present in 5 control subjects (5.6%), but was not found in TH. The incidence of longer variants (>= 16 codons) of FOXE1-polyAla was significantly higher in patients with the familial form of TH in comparison to those with sporadic TH (p = 0.003) and controls (p = 0.005). Conclusions: There is high polymorphic variability of FOXE1-polyAla in both groups. Shorter variants of FOXE1-polyAla are underrepresented in subjects with familial TH. Therefore, FOXE1-polyAla tract expansion may contribute to the molecular background of familial but not sporadic forms of TH. Further studies are still required to confirm such findings. Copyright (c) 2011 S. Karger AG, Basel