Identification of de-novo CREBBP gene variants in patients with Rubinstein-Taybi syndrome.

Rubinstein-Taybi syndrome (RSTS) is an autosomal dominant genetic disease characterized by growth retardation, psychomotor retardation, and distinctive facial features. It is primarily caused by mutations in CREBBP or EP300. In this study, we aimed to describe the clinical manifestations and genetic analyses of two cases with RSTS. Clinical analysis was performed on two cases with RSTS. Molecular diagnoses were made via whole exome sequencing, and potential pathogenic variants were filtered and selected. PCR followed by Sanger sequencing was used to verify candidate variants in the family members. Case 1 involved a 7-year-old boy (patient 1) who exhibited delayed language development, growth retardation, and intellectual disability. We did not find any other characteristics of RSTS, such as thumb or hallux abnormalities. Case 2 involved a fetus who had severe congenital heart disease, low conus medullaris, and a large gallbladder. Whole exome and Sanger sequencing results revealed that a missense mutation c.5120G>A (p. Cys1707Tyr) was present in patient 1 and that the fetus carried a heterozygous nonsense mutation c.1984C>T (p. Gln662Ter). In conclusion, whole exome sequencing combined with Sanger sequencing revealed that c.5120G>A (p. Cys1707Tyr) and c.1984C>T (p. Gln662Ter) are two new mutation sites that cause RSTS. This study expands the clinical phenotypes and is helpful in identifying gene-phenotype correlations in RSTS.