INTERNATIONAL DATABASE OF TETRAHYDROBIOPTERIN DEFICIENCIES

Approximately 2% of newborns with hyperphenylalaninaemia are deficient in tetrahydrobiopterin. Selective screening must be performed in all instances where hyperphenylalaninaemia is detected by neonatal screeni ng, In the last 20 years, 308 patients with tetrahydrobiopterin defici encies have been recognized as a result of screening carried out, worl dwide, in Departments of Paediatrics. Of these 308 patients, 181 suffe red from 6-pyrovoyltetrahydropterin synthase deficiency, 92 from dihyd ropteridine reductase deficiency, 13 from pterin-4a-carbinolamine dehy dratase deficiency, 12 from GTP cyclohydrolase I deficiency, and 10 ar e still unclassified, In the BIODEF database we have tabulated the mos t common clinical and laboratory data related to hyperphenylalaninaemi a and tetrahydrobiopterin deficiencies. Additionally, there are data r egarding treatment, outcome, and DNA analysis. Preliminary evaluation reveals that the degree of hyperphenylalaninaemia can vary from normal to 2,500 mu mol/L. Analyses of pterins in urine and measurement of di hydropteridine reductase activity from Guthrie cards are absolutely es sential tests for accurate diagnosis. There is a regional (demographic ) variation in the frequency of tetrahydrobiopterin deficiencies indic ating the highest incidence in Saudi Arabia, probably a consequence of the high consanguinity rate.