Severe achondroplasia due to two de novo variants in the transmembrane domain of FGFR3 on the same allele: A case report.

This is the second case who had two FGFR3 variants in the transmembrane domain on the same allele. The p.S378N variant may provide an additive effect on the activating receptor with the p.G380R mutation and alter the protein function, which could be responsible for the severe phenotype of the present case.