Novel FGFR1 Variants Are Associated with Congenital Scoliosis

Abstract

FGFR1 encodes a transmembrane cytokine receptor, which is involved in the early development of the human embryo and plays an important role in gastrulation, organ specification and patterning of various tissues. Pathogenic FGFR1 variants have been associated with Kallmann syndrome and hypogonadotropic hypogonadism. In our congenital scoliosis (CS) patient series of 424 sporadic CS patients under the framework of the Deciphering disorders Involving Scoliosis and COmorbidities (DISCO) study, we identified four unrelated patients harboring FGFR1 variants, including one frameshift and three missense variants. These variants were predicted to be deleterious by in silico prediction and conservation analysis. Signaling activities and expression levels of the mutated protein were evaluated in vitro and compared to that of the wild type (WT) FGFR1. As a result, the overall protein expressions of c.2334dupC, c.2339T>C and c.1261A>G were reduced to 43.9%, 63.4% and 77.4%, respectively. By the reporter gene assay, we observed significantly reduced activity for c.2334dupC, c.2339T>C and c.1261A>G, indicating the diminished FGFR1 signaling pathway. In conclusion, FGFR1 variants identified in our patients led to only mild disruption to protein function, caused milder skeletal and cardiac phenotypes than those reported previously.

Overview of Gene Special Issue “Genetic Conditions Affecting the Skeleton: Congenital, Idiopathic Scoliosis and Arthrogryposis”

“…They hypothesize that CNVs in consort with single nucleotide variants, in addition to somatic mutation and environmentally mediated effects, contribute to the occurrence of CS. Wang et al [ 8 ]. identified several hypomorphic sequence variants in FGFR1, a transmembrane cytokine receptor involved in gastrulation, organ specification, and the patterning of various tissues in patients with mild spine and heart defects with CS.…”