Árpád Lábadi1, Elisa Stellaria Grassi1, Balázs Gellén1, Gunnar Kleinau1, Heike Biebermann1, Beáta Ruzsa1, Giulia Gelmini1, Orsolya Rideg1, Attila Miseta1, Gábor L Kovács1, Attila Patócs1, Enikő Felszeghy1, Endre V Nagy1, Emese Mezősi1, Luca Persani1. 1. Department of Laboratory Medicine (A.L., O.R., A.M., G.L.K.), University of Pécs, 7624 Pécs, Hungary; Department of Clinical Sciences and Community Health (E.S.G., L.P.), University of Milan, 20122 Milan, Italy; Department of Pediatrics and Pediatric Health Care Center (B.G.), University of Szeged, 6720 Szeged, Hungary; Institute of Experimental Pediatric Endocrinology (G.K., H.B.), Charité-Universitätsmedizin Berlin, 10117 Berlin, Germany; First Department of Internal Medicine (B.R., E.M.), University of Pécs, 7624 Pécs, Hungary; Division of Endocrine and Metabolic Diseases and Laboratory of Endocrine and Metabolic Research (G.G., L.P.), Ospedale San Luca, Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS) Istituto Auxologico Italiano, 20149 Milan, Italy; Szentágothai Research Centre (G.L.K.), University of Pécs, 7624 Pécs, Hungary; HAS-SE "Lendület" Hereditary Endocrine Tumors Research Group (A.P.), 1085 Budapest, Hungary; and Departments of Pediatrics (E.F.) and Internal Medicine (E.V.N.), Faculty of Medicine, University of Debrecen, 4032 Debrecen Hungary.
Abstract
CONTEXT: Congenital hypothyroidism (CH) is one of the most common inborn endocrine disorders with genetic background. Despite the well-established newborn CH screening program in Hungary, no systematic examination of the underlying genetic alterations has been performed as yet. OBJECTIVE: We aimed to explore TSH receptor (TSHR) mutations in a cohort of Hungarian patients with CH. PATIENTS: Eighty-five unrelated patients with permanent primary CH, all diagnosed at newborn screening, were selected. MAIN OUTCOME MEASURES: Coding exons of the TSHR gene were sequenced and evaluated together with the thyroid-specific clinical parameters. Functional features of the novel mutations were experimentally examined, and their comparative molecular models were built. RESULTS: In four patients (one heterozygous and three compound heterozygous), seven TSHR mutations were identified. Among these, N432(1.50)D and P449(2.39)L are novel missense alterations. Importantly, the N432(1.50) residue is highly conserved among G protein-coupled receptors, and its function has not been examined yet in human glycoprotein hormone receptors. Our results indicate that the N432(1.50)D mutation disrupts important, architecture-stabilizing intramolecular interactions and ultimately leads to the complete intracellular retention of the receptor. On the other hand, P449(2.39) is located in the intracellular part of the receptor, which is important in G protein coupling. The P449(2.39)L mutation results in signaling impairment, with a more profound effect on the Gq/11 pathway. CONCLUSION: TSHR mutations are common among Hungarian patients with CH. The novel genetic alterations revealed an important structural role of the N432(1.50) and the P449(2.39) residues in receptor expression and signaling, respectively.
CONTEXT: Congenital hypothyroidism (CH) is one of the most common inborn endocrine disorders with genetic background. Despite the well-established newborn CH screening program in Hungary, no systematic examination of the underlying genetic alterations has been performed as yet. OBJECTIVE: We aimed to explore TSH receptor (TSHR) mutations in a cohort of Hungarian patients with CH. PATIENTS: Eighty-five unrelated patients with permanent primary CH, all diagnosed at newborn screening, were selected. MAIN OUTCOME MEASURES: Coding exons of the TSHR gene were sequenced and evaluated together with the thyroid-specific clinical parameters. Functional features of the novel mutations were experimentally examined, and their comparative molecular models were built. RESULTS: In four patients (one heterozygous and three compound heterozygous), seven TSHR mutations were identified. Among these, N432(1.50)D and P449(2.39)L are novel missense alterations. Importantly, the N432(1.50) residue is highly conserved among G protein-coupled receptors, and its function has not been examined yet in human glycoprotein hormone receptors. Our results indicate that the N432(1.50)D mutation disrupts important, architecture-stabilizing intramolecular interactions and ultimately leads to the complete intracellular retention of the receptor. On the other hand, P449(2.39) is located in the intracellular part of the receptor, which is important in G protein coupling. The P449(2.39)L mutation results in signaling impairment, with a more profound effect on the Gq/11 pathway. CONCLUSION:TSHR mutations are common among Hungarian patients with CH. The novel genetic alterations revealed an important structural role of the N432(1.50) and the P449(2.39) residues in receptor expression and signaling, respectively.
Authors: Gunnar Kleinau; Catherine L Worth; Annika Kreuchwig; Heike Biebermann; Patrick Marcinkowski; Patrick Scheerer; Gerd Krause Journal: Front Endocrinol (Lausanne) Date: 2017-04-24 Impact factor: 5.555