Screening for inherited metabolic disease in Wales using urine-impregnated filter paper

Area of Science:

• Biochemistry
• Pediatrics
• Medical Diagnostics

Background:

• Newborn screening is crucial for early detection of inborn errors of metabolism.
• Filter paper urine testing offers a non-invasive method for mass screening.
• Accurate diagnostic markers are essential for effective newborn screening programs.

Purpose of the Study:

• To evaluate the efficacy of filter paper urine analysis for detecting various metabolic abnormalities in a large infant cohort.
• To assess the reliability of specific urinary constituents, particularly o-hydroxyphenlacetic acid, as screening markers for phenylketonuria.

Main Methods:

• Collected urine specimens on filter paper from 135,295 infants.
• Utilized spot tests and paper chromatography to analyze for 7 abnormal urinary constituents.
• Compared results with established diagnostic criteria for metabolic disorders.

Main Results:

• Identified 5 cases of phenylketonuria, 4 of histidinaemia, 5 of cystinuria, 5 of diabetes mellitus, and 1 of alcaptonuria.
• Observed transient abnormalities including tyrosyluria, generalized aminoaciduria, cystinuria, and glycosuria.
• Found 2 phenylketonuric infants who did not excrete detectable o-hydroxyphenlacetic acid, indicating a screening limitation.

Conclusions:

• Filter paper urine testing is effective in detecting a range of metabolic disorders in newborns.
• The detection of o-hydroxyphenlacetic acid is an unreliable sole method for screening phenylketonuria.
• Further refinement of screening methods is necessary to ensure comprehensive detection of all affected infants.