Developmental Disabilities

Developmental disabilities, including mental retardation, autism, and cerebral palsy, are imprecise terms in relation to the underlying etiology and the severity of impairments and disabilities each imposes. Mental retardation, for example, has various underlying causes, including chromosomal abnormalities such as Down's Syndrome and Fragile X. Other causes include inborn errors of metabolism (Phenylketonuria, or P.K.U.), environmental toxins (e.g., lead), prenatal infections (rubella, Cytomegolic inclusion virus, or CMV, and HIV/AIDs), maternal ingestion of alcohol during pregnancy (Fetal Alcohol Syndrome/Effects, or FAS/FAE), postnatal infections (e.g., meningitis) and trauma (e.g., stroke or head injury).

As mapping of the human genome proceeds, the interactions between individual genotypes and environmental conditions are becoming ever more specifically defined. Thus, although conventional wisdom attributed much of individual variation to genetic influences, few of these traits are transmitted in a direct manner. The mapping of the human genome will provide the basis for much greater certainty regarding the interactions between genotype and specific environments that result in specific phenotypes. Although such information will undoubtedly improve treatment options eventually, before that benefit is realized such findings will also increase the frequency of families learning the source of the underlying genomic variation in terms of family pedigree. This knowledge can be expected to be a point of considerable stress both for individuals and marital relationships.