title: TSHR is the main causative locus in autosomal recessively inherited thyroid dysgenesis.
abstract: Congenital hypothyroidism (CH) is the most common neonatal endocrine disorder and results in mental retardation if untreated. Eighty-five percent of CH cases are due to disruptions in thyroid organogenesis and are mostly sporadic, but about 2% of thyroid dysgenesis is familial, indicating the involvement of genetic factors in the aetiology of the disease. In this study, we aimed to investigate the Mendelian (single-gene) causes of non-syndromic and non-goitrous congenital hypothyroidism (CHNG) in consanguineous or multi-case families. Here we report the results of the second part (n=105) of our large cohort (n=244), representing the largest such cohort in the literature, and interpret the overall results of the whole cohort. Additionally, 50 sporadic cases with thyroid dysgenesis and 400 unaffected control subjects were included in the study. In familial cases, first, we performed potential linkage analysis of four known genes causing CHNG (TSHR, PAX8, TSHB, and NKX2-5) using microsatellite markers and then examined the presence of mutations in these genes by direct sequencing. In addition, in silico analyses of the predicted structural effects of TSHR mutations were performed and related to the mutation specific disease phenotype. We detected eight new TSHR mutations and a PAX8 mutation but no mutations in TSHB and NKX2-5. None of the biallelic TSHR mutations detected in familial cases were present in the cohort of 50 sporadic cases. Genotype/phenotype relationships were established between TSHR mutations and resulting clinical presentations. Here we conclude that TSHR mutations are the main detectable cause of autosomal recessively inherited thyroid dysgenesis. We also outline a new genetic testing strategy for the investigation of suspected autosomal recessive non-goitrous CH.
authors.affiliation: Centre for Rare Diseases and Personalised Medicine, School of Clinical and Experimental Medicine, University of Birmingham, Birmingham, UK. h.cangul@bham.ac.uk
authors.forename: Hakan
authors.initials: H
authors.lastname: Cangul
authors.forename: Zehra
authors.initials: Z
authors.lastname: Aycan
authors.forename: Halil
authors.initials: H
authors.lastname: Saglam
authors.forename: Julia R
authors.initials: JR
authors.lastname: Forman
authors.forename: Semra
authors.initials: S
authors.lastname: Cetinkaya
authors.forename: Omer
authors.initials: O
authors.lastname: Tarim
authors.forename: Ece
authors.initials: E
authors.lastname: Bober
authors.forename: Yasar
authors.initials: Y
authors.lastname: Cesur
authors.forename: Selim
authors.initials: S
authors.lastname: Kurtoglu
authors.forename: Feyza
authors.initials: F
authors.lastname: Darendeliler
authors.forename: Veysel
authors.initials: V
authors.lastname: Bas
authors.forename: Erdal
authors.initials: E
authors.lastname: Eren
authors.forename: Korcan
authors.initials: K
authors.lastname: Demir
authors.forename: Aslihan
authors.initials: A
authors.lastname: Kiraz
authors.forename: Banu K
authors.initials: BK
authors.lastname: Aydin
authors.forename: Ambika
authors.initials: A
authors.lastname: Karthikeyan
authors.forename: Michaela
authors.initials: M
authors.lastname: Kendall
authors.forename: Kristien
authors.initials: K
authors.lastname: Boelaert
authors.forename: Nick J
authors.initials: NJ
authors.lastname: Shaw
authors.forename: Jeremy
authors.initials: J
authors.lastname: Kirk
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Högler
authors.forename: Timothy G
authors.initials: TG
authors.lastname: Barrett
authors.forename: Eamonn R
authors.initials: ER
authors.lastname: Maher
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D002675:Child, Preschool; D003409:Congenital Hypothyroidism / Q000235:genetics*; D019281:Dimerization; D005260:Female; D005808:Genes, Recessive / Q000235:genetics; D056726:Genetic Association Studies; D006801:Humans; D008297:Male; D018895:Microsatellite Repeats / Q000235:genetics; D017354:Point Mutation / Q000235:genetics; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D011989:Receptors, Thyrotropin / Q000737:chemistry / Q000235:genetics*; D050033:Thyroid Dysgenesis / Q000235:genetics*; D055815:Young Adult
chemical_list: D011989:Receptors, Thyrotropin