Most children have malnutrition secondary to avoidance of eating. Fatty liver and anal stenosis (tightening of the anal sphincter) have also been reported. [rarediseases.org]

Peripheral Muscle Weakness in RASopathies: Handgrip Strength in Costello, Cardio-facio-cutaneous, Noonan and Neurofibromatosis Type 1 Syndromes. Muscle and Nerve. 2012;46(3):394-9. Tidyman WE, HS Lee, KA Rauen. [rarediseases.org]

Signs & Symptoms Most individuals are initially referred because of feeding difficulties (poor suck) and failure to thrive. Later, cognitive developmental delay and other clinical manifestations may be observed. [rarediseases.org]

Feeding/gastrointestinal Severe feeding problems manifest as gastroesophageal reflux (GER), aspiration, vomiting, and affected individuals will avoid eating (avoidance of eating can lead to growth delays). [rarediseases.org]

Peripheral Muscle Weakness in RASopathies: Handgrip Strength in Costello, Cardio-facio-cutaneous, Noonan and Neurofibromatosis Type 1 Syndromes. Muscle and Nerve. 2012;46(3):394-9. Tidyman WE, HS Lee, KA Rauen. [rarediseases.org]

They also have absent or sparse eyebrows and eyelashes. In some children, the nails are dystrophic, with broad flat nails, and/or fast growing. Skin involvement ranges from dry skin to the skin disease known as hyperkeratosis. [rarediseases.org]

Later, cognitive developmental delay and other clinical manifestations may be observed. [rarediseases.org]