Costello syndrome with special cutaneous manifestations and HRAS G12D mutation: A case report and literature review.

Background Costello syndrome (CS, OMIM 218040) is a rare congenital disorder caused by mutations in HRAS. Previous studies reported that approximately 80% of patients with CS share the same pathogenic variant in HRAS gene in c.34G> A (p.G12S). Here, we report a CS patient with c.34G> A (p.G12D) variant in HRAS gene and she presented with special manifestation. Methods and results We describe a 31-year-old female patient who presented with distinctive facial appearance, intellectual disability, dental abnormalities, hyperkeratosis of palmer and planter, loose skin at birth, papillomata on the face and nipples. The whole-exome sequencing (WES) technology provided by Haotian Biotechnology (China) confirmed p.G12D variant in HRAS gene. To elucidate the typical features of CS with p.G12D variant, we further reviewed these previously reported cases and found that patients with G12D variant died within three months after birth due to multiple organ failure. They had the typical facial characteristics, failure to thrive, skin and cardiac abnormalities, and gene testing confirmed the diagnosis of CS. Conclusion To the best of our knowledge, this is the first article to report a patient with a p.G12D variant that had special but mild manifestation. Moreover, this report and literature review casts new light on the clinical features of p.G12D variant.