Genetic Investigation of Regulatory Regions of MKRN3 and DLK1 Genes in Children with Central Precocious Puberty.

Introduction: Most of the loss-of-function mutations described in children with central precocious puberty (CPP) are located in the coding regions of MKRN3 or DLK1 genes. Notably, potential abnormalities in the regulatory regions of these CPP genes are rarely explored. The objective of this work was to identify pathogenic allelic variants in the regulatory regions of MKRN3 and DLK1 genes in patients with familial or idiopathic CPP.

Methods: A cohort of 217 individuals with CPP (205 girls and 12 boys; 143 sporadic cases and 74 familial cases) was investigated. Rare and potentially pathogenic variants in the coding regions of both genes were previously excluded. Analyses of the regulatory regions of MKRN3 and DLK1 were performed using polymerase chain reaction and direct automated sequencing (Sanger method). Circulating serum levels of MKRN3 and DLK1 proteins were measured using an ELISA assay.

Results: We identified a heterozygous allelic variant (c.-265G>A), previously associated with CPP, located in the promoter region of the MKRN3 gene in three girls from two unrelated families. In silico prediction analysis indicated that the c.-265G>A variant was in the ZNF384 binding region. ZNF384 gene encodes a C2H2-type zinc finger protein, which might act as a transcription factor. MKRN3 serum levels varied from 197.5 pg/mL to 1,907 pg/mL and were relatively lower in patients with CPP who carried the c.-265G>A variant. No pathogenic allelic variant was found in the regulatory region of the DLK1 gene.

Conclusion: Pathogenic variants in the regulatory region of MKRN3 gene are rare and can be associated with the CPP phenotype.