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Genetic analysis of the PAX8 gene in children with congenital hypothyroidism and dysgenetic or eutopic thyroid glands: identification of a novel sequence variant
Author(s) -
Tonacchera Massimo,
Banco Maria Elena,
Montanelli Lucia,
Di Cosmo Caterina,
Agretti Patrizia,
De Marco Giuseppina,
Ferrarini Eleonora,
Ordookhani Arash,
Perri Anna,
Chiovato Luca,
Santini Ferruccio,
Vitti Paolo,
Pinchera Aldo
Publication year - 2007
Publication title -
clinical endocrinology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.055
H-Index - 147
eISSN - 1365-2265
pISSN - 0300-0664
DOI - 10.1111/j.1365-2265.2007.02831.x
Subject(s) - pax8 , medicine , endocrinology , congenital hypothyroidism , thyroid , biology , gene , genetics , transcription factor
Summary Objective To analyse the coding region of PAX8 in individuals with congenital (CH) or post neonatal hypothyroidism due to dysgenetic (TD) or eutopic thyroid glands. Design and patients Forty‐three children with CH and TD (13 agenesis, 23 ectopia, and seven hypoplasia), one subject with post neonatal onset of hypothyroidism and thyroid ectopia, 15 children with CH and eutopic thyroid glands and six euthyroid adults with thyroid hemiagenesis were enrolled as cases, along with 120 healthy individuals as controls. Measurements Exons 2–8 of the PAX8 were directly sequenced. HeLa and HEK293 cells were transfected with PAX8 wild‐type ( PAX8 ‐WT), mutant PAX8 , p300, thyroid transcription factor 1 ( TTF‐1 ) and thyroglobulin promoter pGL3 ( TG prom‐pGL3). Synergism of TTF‐1 with PAX8 ‐WT vs. mutant and activity of PAX8 ‐WT vs. mutant in accompaniment with p300 on TG prom‐pGL3 were also assessed. The luminescence produced by PAX8 ‐WT and mutant PAX8 was measured. Results Among patients and controls only a 15‐year‐old girl with thyroid ectopia showed a heterozygous transition of cytosine to thymine at position 674 in exon 6, which changed a conserved threonine at position 225 to methionine ( PAX8 ‐T225M). Her father and sister harboured PAX8 ‐T225M without abnormal thyroid phenotypes. PAX8 ‐T225M and PAX8 ‐WT similarly increased luciferase activity and had a similar synergistic effect with TTF‐1 . At 500 ng p300, however, PAX8 ‐T225M could not significantly increase TG promoter activity when compared to PAX8 ‐T225M alone, while PAX8 ‐WT +500 ng p300 induction was significantly higher than PAX8 ‐WT alone ( P < 0·001). Cotransfection of TTF‐1 together with PAX8 ‐T225M resulted in rescuing of the lack of synergism with p300. Conclusions PAX8 mutations in congenital hypothyroidism due to dysgenetic or orthotopic thyroid glands are rare. PAX8‐T225M is probably a rare variant.