What is Costello Syndrome?

Costello syndrome is a genetic disorder that affects your child’s appearance, development, growth and intellect. It can also affect your child’s heart, skin and joints.

What Causes Costello Syndrome?

Costello syndrome is caused by a mutation (change) in the HRAS gene (piece of DNA). In most cases, the change happens at random. Costello syndrome is not caused by anything you or your partner did.

What Are the Symptoms of Costello Syndrome?

The symptoms of Costello syndrome can affect your child’s body and development. Symptoms can be different for every person.

Developmental symptoms

  • Developmental delays, such as delayed feeding, talking and walking

Physical symptoms

  • Larger-than-average size at birth due to excessive fluid (edema)
  • Slow growth that leads to short stature (reduced height)
  • Distinctive facial appearance, including a large head, low-set ears with large, thick earlobes, thick lips; flat nasal bridge and wide nostrils; curly hair and/or thin hair on the front of the head; and folds of skin over the inner corners of the eyes (epicanthal folds)
  • Weak muscle tone (hypotonia)
  • Very flexible joints
  • Loose skin, especially on the hands and feet
  • Issues with the heart
  • In some cases, papillomata (small, noncancerous bumps), usually around the mouth and nose

Rev. 8/2020. Mass General for Children and Massachusetts General Hospital do not endorse any of the brands listed on this handout. This handout is intended to provide health information so that you can be better informed. It is not a substitute for medical advice and should not be used to treatment of any medical conditions.