Phenylketonuria (PKU) is a hereditary metabolic disorder, in which a deficiency of an enzyme results in the accumulation of the amino acid phenylalanine, resulting in severe mental retardation. It occurs in approximately 1 per 12,000 to 15,000 live births. In most infants diagnosed with PKU, mental retardation can be prevented by restricting dietary phenylalanine, starting before four weeks of age. In 1961, a simple heel-stick test for the condition was developed, and voluntary screening in conjunction with educational programs was initiated soon after in Massachusetts. By 1963, all Massachusetts maternity hospitals had voluntarily enrolled in PKU screening programs and were screening all newborns for PKU. Later that year, Massachusetts became the first state to enact a mandatory screening law.
Although the American Academy of Pediatrics and other professional groups opposed a legislative approach, 43 states have enacted mandatory screening laws, and the rest have set up active testing programs without statutory support. The existing statutes do not punish noncompliant parents. PKU screening is thus an example of a mandatory screening program, with the onus of compliance on maternity hospitals. In 1975, Maryland repealed its compulsory PKU screening law, replacing it with a statute and regulations requiring parental informed consent (Holtzman, 1984). After this change, 99.9% of parents offered newborn screening accepted it (Faden et al., 1982).
Although the PKU program has prevented retardation in thousands of infants, it has been argued that it was introduced prematurely from a medical point of view. Critics of the programs say that the public was led to believe that there was a higher degree of certainty about the results of PKU tests than was the case (NAS, 1975). As a result, some, but probably only a small percentage, of infants identified by the test were incorrectly identified and treated as having PKU. Others have criticized the statutes for not providing either adequate quality assurance mechanisms or adequate funding to care for infants identified as having PKU. The concerns about PKU testing, therefore, are in terms of the third and fourth principle of public health screening described above.
Sickle cell disease (SCD) is an autosomal recessive hemolytic anemia occurring most frequently in African Americans, but also in persons of Mediterranean origin and others. Sickle cell disease, the homozygous condition, is estimated to occur in as many as one in 400 African-American newborns, and approximately 8% of African Americans are carriers of the sickle cell trait, the heterozygous condition. At least 10% of SCD cases in the United States occur in non-African Americans.