ABSTRACT
Developmental delay (DD)=mental retardation (MR) hasmany different causes and is estimated to occur in up to 10% of the population (1). Parents generally want to know the cause of such a disorder in their child, including whether it is genetic (i.e., chromosomal, biochemical, and single gene) or environmental; what can be done about it; whether they will have other children with the same problem; and whether their normal children are at risk for having similar children. To answer these questions and to better understand the clinical
symptoms of the patient, the healthcare professional must recognize the cause of the DD=MR.
