1.5-3% of population
Causes of intellectual disability (30-50% are non-syndromic or idiopathic):
Prenatal factors
- genetic
- Fragile X syndrome
- tuberous sclerosis, neurofibromatosis
- metabolic and storage disorders
- chromosomal
- Down syndrome, Trisomy 18
- Cru di chat syndrome
- sex chromosome abnormality
- dysmorphic syndromes
- Prader-Willi
- Cornelia (Bachman) de Lange syndrome
- Sotos syndrome
- prenatal infections (TORCH)
- drugs and toxins: FAS
Perinatal factors
- hypoxia
- trauma
- infections
- biochemical abnormalities: e.g. female phenylketonurics
Postnatal factors
- trauma
- hypoxia
- meningitis, encephalitis (subacute sclerosing panencephalitis)
- poisons
Further
Galasso C, Lo-Castro A, El-Malhany N, Curatolo P. “Idiopathic” mental retardation and new chromosomal abnormalities. Ital J Pediatr. 2010 Feb 14;36:17. doi: 10.1186/1824-7288-36-17. PMID: 20152051; PMCID: PMC2844383.
Patel DR, Cabral MD, Ho A, Merrick J. A clinical primer on intellectual disability. Transl Pediatr. 2020 Feb;9(Suppl 1):S23-S35. doi: 10.21037/tp.2020.02.02. PMID: 32206581; PMCID: PMC7082244.
