Arguments for early screening: a clinician's perspective

Recent technological advances have led to an expansion in inborn errors that can be detected in the newborn period. Further developments in newborn screening will increase this number further. There are two main arguments put forward to support the developments of an expanded newborn screening programme. Firstly there may be an improvement in patient outcome. The early detection of disorders either in the presymptomatic or early symptomatic phase should, with treatment, result in the prevention of severe illness. This is evident for phenylketonuria and generally accepted for homocystinuria and medium-chain acyl-CoA dehydrogenase deficiency, disorders which have a long presymptomatic phase. However, other inborn errors may present within the first 10 days of life with severe illness, particularly neonatal encephalopathy. In order to effectively stop the rapid progression of these disorders, screening must be undertaken early although where severe metabolic decompensation occurs within 2 to 3 days of birth, newborn screening programmes are unlikely to be of direct benefit. Secondly an early diagnosis, even when this does not affect that individual's prognosis, may allow for accurate genetic advise to be given to the family and the opportunity to have prenatal diagnosis for future pregnancies. Conclusion: For the clinician, the introduction of an expanded and early newborn screening presents opportunities for improved patient and family care. However, it is important to be aware of possible detrimental effects on families of early screening. Screening tests must have adequate sensitivity and high specificity. Furthermore with early screening, close liaison between the laboratory, clinicians and community services is essential.