NEWBORNS ARE screened for phenylketonuria (PKU), congenital hypothyroidism, and sickle cell anemia because treatment is effective if started before symptoms and signs lead to clinical diagnosis. For most of the other disorders for which newborns are screened in most states, treatment is thought to be effective, although evidence has been difficult to collect.1
It comes as a surprise, therefore, that in 19 states, the "follow-up coordinators" of these public health programs (or their designees) thought that children identified by newborn screening might be "unsuitable choices for future reproduction" and that conveying this information should be one of the goals of counseling parents.2 It is true that young women who have been successfully treated for PKU, but who no longer follow the low-phenylalanine diet prior to becoming pregnant, will give birth to impaired infants (maternal PKU). Continuing on the special diet or resuming it periconceptionally can prevent or greatly diminish the harmful effects of maternal PKU.3 It is also true that all of the children born to affected parents who have been successfully treated for autosomal recessive conditions will be obligate heterozygotes. Their only chance of having affected children, however, is if they mate with a heterozygote (or other homozygote); but these children, like their affected parent, can be effectively treated.