Noonan syndrome (NS) belongs to the group of Noonan syndrome spectrum disorders (NSSD), which is a group of phenotypically related conditions. Feeding problems are often present not only in infancy but also in childhood, and even beyond that period. We describe the different aspects of feeding problems using a (theoretical) concept proposed in 2019. More than 50% of infants with NS develop feeding problems, and up to half of these infants will be tube-dependent for some time. Although, in general, there is a major improvement between the age of 1 and 2 years, with only a minority still having feeding problems after the age of 2 years, as long as the feeding problems continue, the impact on the quality of life of both NS infants and their caregivers may be significant. Feeding problems in general improve faster in children with a pathogenic PTPN11 or SOS1 variant. The mechanism of the feeding problems is complex, and may be due to medical causes (gastroesophageal reflux disease and delayed gastric emptying, cardiac disease and infections), feeding-skill dysfunction, nutritional dysfunction with increased energy demand, or primary or secondary psychosocial dysfunction. Many of the underlying mechanisms are still unknown. The treatment of the feeding problems may be a medical challenge, especially when the feeding problems are accompanied by feeding-skill dysfunction and psychosocial dysfunction. This warrants a multidisciplinary intervention including psychology, nutrition, medicine, speech language pathology and occupational therapy.
Keywords: Noonan syndrome; Noonan syndrome spectrum disorder; gastroesophageal reflux disorder; increased energy demand; pediatric feeding disorder.