(costello syndrome) A genetic syndrome caused by mutations in the HRAS gene. It is characterized by developmental delay, mental retardation, loose skin folds, cardiomyopathy, tachycardia, and structural heart defects. Patients are at an increased risk of developing benign or malignant neoplasms.

(costello syndrome) An autosomal dominant syndrome caused by mutations in the HRAS gene, encoding GTPase HRas, a signaling molecule involved in control of cell growth and division. The condition is characterized by coarse facial features, loose skin folds, developmental delays, hypotonia, multiple cardiac problems (structural heart anomalies, hypertrophic cardiomyopathy), short stature, hyperinsulinism, and an increased risk for development of neoplasia.

(costello syndrome) Rare congenital disorder with multiple anomalies including: characteristic dysmorphic craniofacial features, musculoskeletal abnormalities, neurocognitive delay, and high prevalence of cancer. Germline mutations in H-Ras protein can cause Costello syndrome. Costello syndrome shows early phenotypic overlap with other disorders that involve MAP KINASE SIGNALING SYSTEM (e.g., NOONAN SYNDROME and cardiofaciocutaneous syndrome).

While the majority of individuals with Costello syndrome share characteristic findings affecting multiple organ systems, the phenotypic spectrum is wide, ranging from a milder or attenuated phenotype to a severe phenotype with early lethal complications. Costello syndrome is typically characterized by failure to thrive in infancy as a result of severe postnatal feeding difficulties; short stature; developmental delay or intellectual disability; coarse facial features (full lips, large mouth, full nasal tip); curly or sparse, fine hair; loose, soft skin with deep palmar and plantar creases; papillomata of the face and perianal region; diffuse hypotonia and joint laxity with ulnar deviation of the wrists and fingers; tight Achilles tendons; and cardiac involvement including: cardiac hypertrophy (usually typical hypertrophic cardiomyopathy), congenital heart defect (usually valvar pulmonic stenosis), and arrhythmia (usually supraventricular tachycardia, especially chaotic atrial rhythm/multifocal atrial tachycardia or ectopic atrial tachycardia). Relative or absolute macrocephaly is typical, and postnatal cerebellar overgrowth can result in the development of a Chiari I malformation with associated anomalies including hydrocephalus or syringomyelia. Individuals with Costello syndrome have an approximately 15% lifetime risk for malignant tumors including rhabdomyosarcoma and neuroblastoma in young children and transitional cell carcinoma of the bladder in adolescents...

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...