Costello Syndrome
Costello syndrome is a rare condition that affects many different parts of the body. Signs and symptoms generally include developmental delay, intellectual disability, distinctive facial features, loose folds of extra skin (especially on the hands and feet), and unusually flexible joints. Affected people may also have heart abnormalities such as tachycardia, structural heart defects, and hypertrophic cardiomyopathy. Beginning in early childhood, people with Costello syndrome additionally have an increased risk to develop certain cancerous and noncancerous tumors. Costello syndrome is caused by changes (mutations) in the HRAS gene. It is considered an autosomal dominant condition, but almost all cases are the result of de novo gene mutations and occur in people with no family history of the condition. Treatment is based on the signs and symptoms present in each person.
Costello syndrome belongs to a group of related conditions called the RASopathies. These conditions have some overlapping features and are all caused by genetic changes that disrupt the body's RAS pathway, affecting growth and development. The features of Costello syndrome overlap significantly with two of the RASopathies, cardiofaciocutaneous (CFC) syndrome and Noonan syndrome.