Intellectual disability in Indian children: experience with a stratified approach for etiological diagnosis

To study the clinico-etiological profile of children with intellectual disability using an algorithmic approach. Cross-sectional study. Tertiary care centre in Northern India. Consecutive children aged 3 months to 12 years, presenting with intellectual disability, confirmed by Developmental Assessment Scale for Indian Infants, Binet Kulshreshtha Test and Vineland Social Maturity Scale. All children were assessed on an internally validated structured proforma. A targeted approach included thyroid function tests, Brainstem evoked response audiometry, electroencephalogram, neuroimaging and metabolic screen done as a pre-decided schema. Genetic tests included karyotyping, molecular studies for Fragile X, Multiplex Ligation Dependent Probe Amplification and Array Comparative Genomic Hybridisation. Data of 101 children (median age 22 months) was analyzed. The etiological yield was 82.1% with genetic causes being the most common (61.4%) followed by perinatal acquired (20.4%), CNS malformations (12%), external prenatal (3.6%), and postnatal acquired (2.4%). Mild delay was seen in 11.7%, moderate in 21.7%, severe in 30.6% and profound in 35.6%. It is possible to ascertain the diagnosis in most of the cases of intellectual disability using a judicious and sequential battery of tests.