Functional Validation and Phenotypic Spectrum of Splice‐Site Variants in <scp> <i>CHD7</i> </scp> , <scp> <i>FGFR1</i> </scp> , and <scp> <i>ANOS1</i> </scp> in Congenital Hypogonadotropic Hypogonadism

To determine the prevalence of CHD7, FGFR1 and ANOS1 variants and the impacts of their splicing variants on mis-splicing in patients with congenital hypogonadotropic hypogonadism (CHH). Based on the whole-exome sequencing data from 280 CHH probands, we identified 15 potential splice-site variants in CHD7, ANOS1 and FGFR1 by using in silico software. The functional consequences of these variants were analyzed by the minigene assay or RT-PCR analyses of RNA taken from the peripheral lymphocytes. Detailed phenotyping was performed in the CHH patients harboring deleterious variants and their available family members. 11 out of 15 potential splice-site variants were demonstrated to cause mis-splicing, resulting in loss of function through deletion, insertion or frameshift of amino acids in the proteins. Most patients with deleterious splice-site variants in CHD7, ANOS1, FGFR1 presented with gene-specific non-reproductive phenotypes, confirming the pathogenic contribution of these variants to CHH. Our study indicated that splice-site variants in CHD7, ANOS1, FGFR1 underlie the genetic basis of ~3.9% of CHH patients, warranting the inclusion of potential splice-site variants for genetic diagnosis and counseling of CHH.