FGFR2 mutation in a patient without typical features of Pfeiffer syndrome--The emerging role of combined NGS and phenotype based strategies.

Pfeiffer syndrome (MIM: #101600) is a rare autosomal dominant disorder classically characterized by limb and craniofacial anomalies. It is caused by heterozygous mutations in the fibroblast growth factor receptors types 1 and 2 (FGFR1 and FGFR2). We applied a next generation sequencing (NGS) panel approach comprising all 2877 genes currently known to be causative for one or more Mendelian diseases combined with the phenotype based computational tool PhenIX (Phenotypic Interpretation of eXomes). We report on a patient presenting with multiple anomalies of hands and feet including brachydactyly and symphalangism. No clinical diagnosis could be established based on the clinical findings and testing of several genes associated with brachydactyly and symphalangism failed to identify mutations. Via next generation sequencing (NGS) panel approach we then identified a novel de novo missense FGFR2 mutation affecting an amino acid reported to be mutated in Pfeiffer syndrome. Since our patient shows typical radiological findings of Pfeiffer syndrome in hands and feet but at the same time lacks several characteristic features such as clinical signs of craniosynostosis and prominent eyes we suggest introducing the term "FGFR2 associated phenotypes" for similar cases. Our results highlight the emerging role of combined NGS and phenotype based bioinformatics strategies to establish clinical diagnoses.