Genotype-phenotype correlations in Rubinstein-Taybi syndrome

Area of Science:

• Genetics
• Molecular Biology
• Developmental Biology

Background:

• Rubinstein-Taybi syndrome (RTS) is a rare genetic disorder characterized by intellectual disability and distinctive physical features.
• Loss-of-function mutations in CREBBP or EP300 genes are identified in approximately 50% of RTS patients.

Purpose of the Study:

• To investigate genotype-phenotype correlations in Rubinstein-Taybi syndrome.
• To analyze the impact of different CREBBP mutation types on patient phenotypes.

Main Methods:

• Genomic DNA analysis of CREBBP gene (31 coding exons and junctions) in 93 RTS patients.
• Fluorescence in situ hybridization (FISH) for large deletions in a subset of patients.
• Detailed phenotypic data collection and correlation with mutation types (missense, truncating, splice-site, large deletions, no CREBBP mutation).

Main Results:

• Sixty-four variations were found, with 52 patients (56%) having definitive CREBBP mutations (10 missense, 36 truncating/splice-site, 6 large deletions).
• All groups showed characteristic facial and thumb abnormalities.
• Growth retardation was more frequent in patients without CREBBP mutations, while seizures were more common with CREBBP mutations.

Conclusions:

• Phenotypic similarity across different mutation groups suggests a shared downstream pathway for genes involved in RTS.
• While specific phenotypes like growth and seizures correlate with mutation presence/type, overall intellectual disability and core features are consistent.
• Further research into the common pathway is warranted.