Identification of Diagnostic Variants in FGFR2 and NPR2 Genes in a Chinese Family Affected by Crouzon Syndrome and Acromesomelic Dysplasia, Type Maroteaux.

This study aims to conduct a comprehensive clinical and genetic investigation on a large family with members having various phenotypes, including acromesomelic dysplasia, type Maroteaux (AMDM), idiopathic short stature (ISS), Crouzon syndrome (CS). Prenatal diagnosis was performed on the high-risk fetus. We performed the whole-exome sequencing on three members with AMDM, ISS, or CS. Detailed genotypes and phenotypes were investigated on members of this 4-generation family. Genetic analysis identified three variants, which were designated as p.Val548del, p.Arg989Gln in natriuretic peptide receptor B/guanylate cyclase B (NPR2), and p.Cys342Tyr in fibroblast growth factor receptor-2 (FGFR2). Compound heterozygous variation consisting of p.Val548del and p.Arg989Gln caused AMDM. NPR2 heterozygous variant carriers exhibited normal height or ISS. The p.Cys342Tyr mutation of FGFR2 causes the typical clinical phenotype of CS. The fetus carried the heterozygous p.Val548del and p.Cys342Tyr mutations, with ultrasound results showing exophthalmos, parrot-beaked nose, low and flat frontal skull, and intrauterine growth retardation at the second and third trimesters of gestation. We are reporting those two novel mutations (p.Val548del and p.Arg989Gln) in NPR2 and a p.Cys342Tyr mutation in FGFR2 in an extended Chinese family. This finding extended the genotype-phenotype spectra of ISS, AMDM, and CS related to pathogenic variants.