In a study that was conducted in 21 Alagille and 100 congenital hypothyroidism patients by de Filippis et al (20), some variants in the JAG1 gene were found in cases with congenital thyroid defects and unexplained mild hypothyroidism was present in a 28.6% of the Alagille syndrome patients (20). Here, JAG1 is linked to hypothyroidism.