Neonatal screening: from the 'Guthrie age' to the 'genetic age'.

Newborn screening has 'traditionally' been performed to detect metabolic or endocrine diseases that are severe, frequent and treatable, according to criteria established in the late 1960s. Technological advances in laboratory testing over the past ten years open new possibilities. However, many new problems have to be explored before the establishment or expansion of a newborn screening programme. The purpose of this paper is to present some of the major problems that screening programmes will face in the near future.