Neonatal Screening for Congenital Hypothyroidism: What Can We Learn from Discordant Twins

Emanuela Medda, Maria Cristina Vigone, Alessandra Cassio, Francesca Calaciura, Pietro Costa, Giovanna Weber, Tiziana De Filippis, Giulia Gelmini, Marianna Di Frenna, Silvana Caiulo, Rita Ortolano, Daniela Rotondi, Monica Bartolucci, Rossella Gelsomino, Simona De Angelis, Marco Gabbianelli, Luca Persani, Antonella Olivieri

Research output: Contribution to journalArticlepeer-review


Newborn screening program for congenital hypothyroidism (CH) adopting rescreening in at-risk neonates. Objectives: To estimate the concordance rate for CH in twin pairs discordant at the first screening; to verify whether long-term follow-up of healthy cotwins belonging to CH discordant pairs may be useful to diagnose thyroid hypofunction during development; to evaluate the importance of genetic and environmental influences on liability to permanent and transient CH. Design and Patients: Forty-seven screening discordant twin pairs were investigated. Proband was defined as the twin in the pair with a positive test at the first screening and a confirmed diagnosis of CH. Results: Seven screening discordant twin pairs became concordant for CH within the first month of life (pairwise concordance of 14.9%) because seven screening negative cotwins showed high TSH values when retested. During long-term follow-up (range, 3 to 21 years), hypothyroidism was diagnosed in two monozygotic screening negative cotwins at the age of 9 months and 12 years, respectively. Furthermore, the twin analysis showed that 95% of liability to transient CH was explained by genetic factors and 5% by environmental (unshared) factors, whereas 64% of phenotypic variance of permanent CH was explained by common environmental factors (shared during the fetal life) and 36% by unshared environmental factors. Conclusions: This study showed that the introduction of rescreening permits the diagnosis of CH in a greater number of twins. It also showed the importance of long-term follow-up in both twins in the pair, and the role of nongenetic factors in the etiology of permanent CH.

Original languageEnglish
Pages (from-to)5765-5779
Number of pages15
JournalJournal of Clinical Endocrinology and Metabolism
Issue number12
Publication statusPublished - Aug 13 2019

ASJC Scopus subject areas

  • Endocrinology, Diabetes and Metabolism
  • Biochemistry
  • Endocrinology
  • Clinical Biochemistry
  • Biochemistry, medical


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