Assessing genotype-phenotype correlation in Costello syndrome using a severity score

Area of Science:

• Genetics
• Rare Diseases
• Human Physiology

Background:

• Costello syndrome is a rare genetic disorder characterized by multisystemic involvement.
• Germline mutations in the HRAS gene are the known cause of Costello syndrome.
• Previous reports indicate various missense mutations within the HRAS gene.

Purpose of the Study:

• To develop and apply a severity scoring system for Costello syndrome.
• To assess the potential genotype-phenotype correlation in Costello syndrome.
• To quantitatively evaluate phenotypic severity in a cohort of individuals with Costello syndrome.

Main Methods:

• A severity scoring system was developed based on medically relevant manifestations.
• Records of 78 individuals with Costello syndrome were scored blindly at different life stages.
• Statistical analysis, including mixed-model repeated-measures ANOVA, was used to compare severity scores across different HRAS mutations.

Main Results:

• Individuals with HRAS mutations p.G12A or p.G12C exhibited more severe phenotypes compared to other mutations.
• Phenotypic severity did not show a significant increase over time, irrespective of the specific HRAS mutation.
• The study identified a potential genotype-phenotype correlation, although based on a small sample size.

Conclusions:

• This study provides the first quantitative assessment of phenotypic severity in Costello syndrome.
• The findings support a medically relevant genotype-phenotype correlation in Costello syndrome.
• Limitations include a small sample size for rare mutations and potentially incomplete medical records.