Targeted Resequencing of Putative Growth-Related Genes Using Whole Exome Sequencing in Patients with Severe Primary IGF-I Deficiency

Abstract

Background/Aims: To elucidate the genetic causes of severe primary insulin-like growth factor-I deficiency (SPIGFD) by systematic, targeted, next-generation sequencing (NGS)-based resequencing of growth-related genes. Methods: Clinical phenotyping followed by NGS in 17 families including 6 affected sib pairs. Results: We identified disease-causing, heterozygous, de novo variants in HRAS (p.Gly13Cys) and FAM111A (p.Arg569His) in 2 male patients with syndromic SPIGFD. A previously described homozygous GHR nonsense variant was detected in 2 siblings of a consanguineous family (p.Glu198*). Furthermore, we identified an inherited novel variant in the IGF2 gene (p.Arg156Cys) of a maternally imprinted gene in a less severely affected father and his affected daughter. We detected 2 other novel missense variants in SH2B1 and SOCS2, both were inherited from an unaffected parent. Conclusions: Screening of growth-related genes using NGS-based, large-scale, targeted resequencing identified disease-causing variants in HRAS, FAM111A, and GHR. Considering the increased risk of subjects with HRAS mutations for neoplasms, close clinical monitoring and a thorough discussion of the risk/benefit ratio of the treatment with recombinant IGF-I is mandatory. Segregation analysis proved to be critical in the interpretation of potential SPIGFD-associated gene variations.