Genetics of Costello Syndrome

Costello syndrome is suspected to be caused by a genetic mutation and this disorder is very rare. This disorder affects several body systems. The exact incidence of this disorder is unknown and only about 150 reports of this disorder have been published in medical literature worldwide. Costello syndrome symptoms vary greatly and depend on the body systems affected.

HRAS gene mutations cause Costello syndrome. This gene gives the necessary instructions to make the N-Ras protein, a protein necessary for helping control the growth and division of cells. When the HRAS gene is mutated, it causes H-Ras protein production to be continuously active. This disorder is considered an autosomal dominant disorder.

Costello syndrome symptoms vary greatly because this disorder affects so many different body systems. The symptoms can include:

• Difficulty growing and gaining weight after birth, resulting in short stature
• Non-cancerous growths developing around the nostrils and mouth
• Mental retardation
• Abnormally flexible finger joints
• Excessive loose skin on the fingers, palms of the hands, neck, and soles of the feet
• Characteristic facial features, such as wide nostrils, large head, large lips, and low-set ears with thick, large lobes
• Dry, thickened skin on the arms and legs, or hands and feet

Doctors will begin diagnosing this disorder by performing a physical exam and getting the patient's personal and family medical history. The doctor will then often notice the characteristic facial features that Costello syndrome patients have. They will then evaluate the patient's other symptoms, such as difficulty feeding, growing, and gaining weight. As of now, there are no specific tests for this disorder. Doctors make the diagnosis based on the patient's physical appearance and symptoms.

In the future, there could be genetic testing available to test for an HRAS gene mutation. Genetic testing would be beneficial because it could greatly help with diagnosis.

Costello syndrome cannot be cured and there is no specific course of treatment for this disorder. The primary focus of treatment is controlling the symptoms that Costello syndrome causes.

A thorough cardiology evaluation is often done, and is very beneficial, in helping to look for heart disease or the heart defects that are common with this disorder.

Occupational and physical therapy can help patient's reach their developmental potential.

It is crucial for patients to be regularly monitored for spine or orthopedic problems, tumor growth, blood pressure changes, or heart changes.

Patients with this disorder that are healthy can live a normal lifespan. Those with cancerous tumors or heart problems could face difficulties and may not live a normal lifespan. A patient's lifespan is completely dependent on their symptoms, associated disorders, and quality and consistency of medical care.

Genetics Home Reference. (2008). Costello Syndrome. Retrieved on July 30, 2010 from Genetics Home Reference: http://ghr.nlm.nih.gov/condition/costello-syndrome

University of Washington Gene Reviews. (2009). Costello Syndrome. Retrieved on July 30, 2010 from the University of Washington Gene Review: http://www.ncbi.nlm.nih.gov/bookshelf/br.fcgi?book=gene&part=costello