New Insight into the genotype-phenotype correlation of PTH1R variants and primary failure of tooth eruption on an Italian Cohort.

Primary failure of tooth eruption (PFE) is an autosomal dominant disease with penetrance defect. While the clinical phenotype is relatively well-defined since the 70 s of the last centuries, much more need to be clarified about the genetic causes of this condition. In our previous paper we established clinical criteria to better identify PFE patients carrying PTH1R gene variants. We examined a new cohort of 32 patients, including one or more relatives for 7 patients (43 cases in total), referred to have PFE and recruited from our Hospital and from external outpatients. Sequencing analysis of the PTH1R coding sequence in this cohort of patients revealed 9 different variants, 4 exonic and 5 intronic. Through in silico prediction tools and databases, 3 of them (2 exonic and 1 in a splicing site) had been considered potentially involved in the PFE phenotype. Sequencing of cDNA was unsuccessfully attempted due to the low levels of PTH1R expression in the analysed tissues. The yield of the genetic test increases when the clinical selection of the patients with dental eruption failure is well-characterized. Dental eruption failure with pure clinical findings of PFE associated with familial history revealed variants in PTH1R gene, offering a diagnostic test for the family. Characterization of novel variants in the most relevant responsible gene of the PFE could bring to a more accurate diagnosis and therapeutic approach in the future and to a deeper comprehension of the disease.