Table 1.

Terms used for search strategy in Pubmed.

Neurocognitive regression	Progressive intellectual and neurologic deterioration, PIND, neurologic/neurocognitive/psychomo tor/mental/cognitive/developmental/intellectual regression/deterioration/decline, developmental arrest, dementia, loss of skill(s), loss of milestone(s), neurobehavioral signs and symptoms, loss of (intellectual) abilities, disintegrative/neurodegenerative disease/disorder.
Inborn errors of metabolism	Inborn/inherited errors of metabolism, inborn/inherited/genetic metabolic/neurometabolic/ metabolic brain disorder/disease, IEMs
Age group	Newborn, infant, child, pediatric,
(birth-18 years)	adolescent.