Phenylketonuria is still a major cause of mental retardation in Tunisia despite the possibility of treatment.

Background And Objective: Accumulation of phenylalanine following a deficiency of phenylalanine hydroxylase activity generates a brain damage with mental retardation: phenylketonuria (PKU). In the developing countries, where PKU systematic neonatal screening program is not established yet, the management of PKU handicap is not properly carried out. The aim of this study was to estimate the frequency of the PKU diagnosed following clinical features anomalies, to provide information about the untreated PKU patients profile in Tunisia not covered by neonatal screening.

Expanded newborn screening: social and ethical issues.

Newborn screening and genetic testing have expanded rapidly in the last decade with the advent of multiplex (e.g., tandem mass spectrometry) and/or DNA technologies.

Lessons from 30 years of selective screening for tetrahydrobiopterin deficiency.

In addition to being hyperphenylalaninemic, patients lacking tetrahydrobiopterin (BH4) are deficient in the neurotransmitters whose synthesis depends on the normal activity of tetrahydrobiopterin-dependent tyrosine and tryptophan hydroxylases. Consequently, these patients have to be rapidly recognized among hyperphenylalaninemic babies, since they need specific and early substitutive therapy. Since 1980, BH4 metabolism has been investigated in 2,186 hyperphenylalaninemic babies, using HPLC measurement of pteridines in urine to recognize tetrahydrobiopterin synthesis deficiency (GTP cyclohydrolase and PTPS deficiency) and direct DHPR assay in dried blood samples to recognize DHPR deficiency.

Implementation of the French nationwide cystic fibrosis newborn screening program.

Objectives: To describe optimization of a nationwide newborn screening program for cystic fibrosis (CF) that combines an immunoreactive trypsinogen (IRT) assay and DNA mutation analysis in dried blood samples at day 3.

Study Design: Data from regional screening laboratories and CF care centers were centralized and periodically analyzed to allow adaptation, thus limiting the number of false-positive cases.

Results: A total of 2717905 infants were screened between 2002 and 2005.

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.

Implementation of informed consent for a cystic fibrosis newborn screening program in France: low refusal rates for optional testing.

Objectives: The French Association for Neonatal Screening implemented cystic fibrosis neonatal screening (CF NBS) region by region in France, from the beginning of the year 2002 to early 2003. The program uses an immunoreactive trypsinogen/DNA testing algorithm on dried blood samples obtained at 3 days of age. Incorporation of DNA testing necessitated compliance with official regulations and French "bioethics" laws: the need for a written consent from the patient/guardian and specific circulation of the prescription, sample, and results.

Difficulties in establishing reference intervals for special fluids: the example of 5-hydroxyindoleacetic acid and homovanillic acid in cerebrospinal fluid.

Biochemical measurements in "special fluids" are complicated with the problem of reference intervals. Reference intervals are difficult to establish for these types of samples since they are usually only collected in patients with clinical suspicion of disease. Determination of neurotransmitter metabolites in cerebrospinal fluid illustrates this difficulty.