title: Functional zebrafish studies based on human genotyping point to netrin-1 as a link between aberrant cardiovascular development and thyroid dysgenesis.
abstract: Congenital hypothyroidism caused by thyroid dysgenesis (CHTD) is a common congenital disorder with a birth prevalence of 1 case in 4000 live births, and up to 8% of individuals with CHTD have co-occurring congenital heart disease. Initially we found nine patients with cardiac and thyroid congenital disorders in our cohort of 158 CHTD patients. To enrich for a rare phenotype likely to be genetically simpler, we selected three patients with a ventricular septal defect for molecular studies. Then, to assess whether rare de novo copy number variants and coding mutations in candidate genes are a source of genetic susceptibility, we used a genome-wide single-nucleotide polymorphism array and Sanger sequencing to analyze blood DNA samples from selected patients with co-occurring CHTD a congenital heart disease. We found rare variants in all three patients, and we selected Netrin-1 as the biologically most plausible contributory factor for functional studies. In zebrafish, ntn1a and ntn1b were not expressed in thyroid tissue, but ntn1a was expressed in pharyngeal arch mesenchyme, and ntn1a-deficient embryos displayed defective aortic arch artery formation and abnormal thyroid morphogenesis. The functional activity of the thyroid in ntn1a-deficient larvae was, however, preserved. Phenotypic analysis of affected zebrafish indicates that abnormal thyroid morphogenesis resulted from a lack of proper guidance exerted by the dysplastic vasculature of ntn1a-deficient embryos. Hence, careful phenotyping of patients combined with molecular and functional studies in zebrafish identify Netrin-1 as a potential shared genetic factor for cardiac and thyroid congenital defects.
authors.affiliation: Institute of Interdisciplinary Research in Molecular Human Biology (R.O., I.V., A.T., S.C.), Université Libre de Bruxelles, 1070 Brussels, Belgium; Research Center of Centre Hospitalier Universitaire Sainte-Justine (M.-P.H., I.V., R.A.-K., M.S., G.A., J.D.), Department of Pediatrics, Université de Montréal, Montréal, Québec, Canada H3T 1C5; and Department of Medical Genetics (V.D.), Centre Hospitalier Universitaire de Sherbrooke, Sherbrooke, Canada J1H 1P8.
authors.forename: Robert
authors.initials: R
authors.lastname: Opitz
authors.forename: Marc-Philip
authors.initials: MP
authors.lastname: Hitz
authors.forename: Isabelle
authors.initials: I
authors.lastname: Vandernoot
authors.forename: Achim
authors.initials: A
authors.lastname: Trubiroha
authors.forename: Rasha
authors.initials: R
authors.lastname: Abu-Khudir
authors.forename: Mark
authors.initials: M
authors.lastname: Samuels
authors.forename: Valérie
authors.initials: V
authors.lastname: Désilets
authors.forename: Sabine
authors.initials: S
authors.lastname: Costagliola
authors.forename: Gregor
authors.initials: G
authors.lastname: Andelfinger
authors.forename: Johnny
authors.initials: J
authors.lastname: Deladoëy
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D018376:Cardiovascular Abnormalities / Q000235:genetics*; D005260:Female; D018507:Gene Expression Regulation, Developmental / Q000502:physiology*; D055785:Gene Knockdown Techniques; D020022:Genetic Predisposition to Disease; D005838:Genotype; D006801:Humans; D008297:Male; D060172:Morpholinos; D009414:Nerve Growth Factors / Q000235:genetics / Q000378:metabolism*; D000075388:Netrin-1; D020641:Polymorphism, Single Nucleotide; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D050857:Synaptotagmins / Q000235:genetics / Q000378:metabolism; D050033:Thyroid Dysgenesis / Q000235:genetics*; D025521:Tumor Suppressor Proteins / Q000235:genetics / Q000378:metabolism*; D029961:Zebrafish Proteins
chemical_list: D060172:Morpholinos; C000617351:NTN1 protein, human; D009414:Nerve Growth Factors; D012333:RNA, Messenger; C511935:SYT17 protein, human; D025521:Tumor Suppressor Proteins; D029961:Zebrafish Proteins; C000617355:ntn1a protein, zebrafish; D050857:Synaptotagmins; D000075388:Netrin-1