Costello syndrome is caused by a mutation (abnormality) of the HRAS gene. Only about 350 reports of Costello syndrome have been published in worldwide medical literature, so it is not clear how often the syndrome actually occurs or who is more likely to be affected by it.
Symptoms Most children with Costello syndrome have difficulty eating, gaining weight, and growing.
Typical symptoms of Costello syndrome are:
Difficulty gaining weight and growing after birth, which leads to short statureExcessive loose skin on the neck, palms of the hands, fingers, and soles of the feet (cutis laxa)Noncancerous growths (papillomata) around the mouth and nostrilsCharacteristic facial appearance such as a large head, low-set ears with large, thick lobes, thick lips, and/or wide nostrilsMental retardationThickened, dry skin on the hands and feet or arms and legs (hyperkeratosis)Abnormally flexible joints of the fingers....