Denis Cyr

Quebec neonatal mass urinary screening programme: From micromolecules to macromolecules

SummaryThe Quebec Mass Urinary Screening Programme, initiated in 1971, has resulted in the screening of more than 2 500 000 newborns in the province of Quebec for 25 inherited Mendelian disorders divided into two groups. The first group concerns urea cycle disorders (citrullinaemia, hyperargininaemia, argininosuccinic aciduria), ketotic hyperglycinaemia, and organic acidurias (methylmalonic aciduria, glutaric aciduria type I, etc.); the second group relates to disorders of amino acid metabolism (cystathioninuria, prolidase deficiency, etc.) and transport (Fanconi syndrome, cystinurias, Hartnup syndrome, etc.). The main goal of the Programme is to detect and prevent these genetic diseases, some detectable only in urine, before the onset of clinical symptoms. A multiplex thin-layer chromatography methodology was developed, in which metabolites in urine are resolved and visualized by the sequential application of four different reagents to detect aminoacidopathies and organic acidurias. The technique is simple, reproducible, inexpensive and rapid, allowing the analysis of 500 samples daily by a single technician. The voluntary compliance of the parents is excellent, averaging 90% per year. Over the years, we have established a dynamic process, developing techniques or new reagents to detect as many treatable disorders as possible, now evaluating macromolecules associated with lysosomal storage disorders, mainly globotriaosylceramide (Gb3) for Fabry disease. We present here the methodology, infrastructure in place, results and recent statistics of the well-established Quebec Mass Urinary Screening Programme. We also report a study by tandem mass spectrometric analysis of urinary Gb3 in Fabry disease for the follow-up and monitoring of Fabry patients, as well as for its possible application to mass and high-risk screening programmes.

Development of a filter paper method potentially applicable to mass and high-risk urinary screenings for Fabry disease

SummaryFabry disease is an X-linked lysosomal storage disorder of glycosphingolipid catabolism resulting from a deficiency of the enzyme α-galactosidase A, and leading to the progressive accumulation of one biomarker, globotriaosylceramide (Gb3), predominantly elevated in the urine of these patients. We have developed a technique for the analysis of total Gb3 in urine samples collected on filter paper, using liquid chromatography–tandem mass spectrometry (LC-MS/MS) with a triple quadrupole instrument. Existing Gb3 techniques being both time- and labour-intensive, this filter paper method eliminates lipid extraction, glycolipid isolation, centrifugation and evaporation steps, while maintaining sensitivity and efficiency. The stability of Gb3 on filter paper was good for a 7-week period under different temperature conditions. Normal control values were established and the technique was tested with anonymized samples from Fabry hemizygotes and heterozygotes. The levels of total Gb3 in all classical hemizygotes were well above the control values and all heterozygotes, except two nonexcretors, were above the reference level. The proposed novel filter paper method favours the collection, storage and shipment of samples. It is simple and efficient for a feasibility study, potentially applicable to the determination of total urinary Gb3 in the newborn population as part of a screening programme, and could also be used in high-risk screening laboratories. Since the incidence of Fabry disease is hard to establish, owing to the heterogeneous clinical expression of the visible phenotype, this feasibility study could help determine its actual incidence in the Quebec population.

Stability of urinary HVA and VMA on filter paper

The study examined the stability of HVA and VMA in 1-ml aliquots of a single urine sample stored on filter paper at different temperatures for 2 years. The results showed that HVA and VMA were stable in dried filter paper when stored at 4 degrees C or lower temperature. Storage at room temperature resulted in degradation of the sample.

Use of urinary globotriaosylceramide for fabry disease screening in Canada

2008 S79 Clin Ther. 2008;30(Suppl C):S79–S80