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A screening programme for early detection of inborn errors of metabolism in Polish newborn population has been evaluated. Guthrie bacterial inhibition assay for amino-acidopathies, Beutler and Baluda test for galactosemia, meconium test and ion-selective chloride electrode for cystic fibrosis, radioimmunological test for congenital hypothyroidism, and multidirectional urine screening test are described and the results discussed.

The results and the significance of neonatal mass-screening programmes for inborn errors of metabolism, conducted by the National Research Institute of Mother and Child (NRIMC), are discussed. As the first in Poland, in 1964, mass-screening for phenylketonuria (PKU) was introduced. The BIA-Guthrie test was used. Other Guthrie tests (GBIA) were applied in homocystinuria, tyrosinemia, histidinemia and leucinosis (Maple Syrup Urine Disease-MSUD). In the middle of the 60. the Beutler and Baluda test was introduced for galactosaemia, as well as the Efron urine test in infant screening for different inborn errors of metabolism. In the middle of the 70., neonatal mass-screening for cystic fibrosis (CF, mucoviscidosis) was started. Meconium tests and the sweat test with ion selective chloride electrode were used. Apart from inborn errors of metabolism, we also introduced a screening programme for neuroblastoma in which vaniline mandelic acid (VMA) in urine was estimated and for congenital hypothyroidism were TSH level was assessed. The results of screening are shown in the tables and in the figures. In our opinion the best clinical results are obtained with screening for congenital hypothyroidism and for PKU, since very early detection and treatment in these diseases prevents severe mental retardation. We therefore consider that both these screening programmes should be treated as obligatory examinations in all neonates. Taking into consideration the fact that there are different types of hyperhenylalaninemias, the principles of differential diagnosis are discussed. Molecular genetic investigations, carried out in the NRIMC Department of Genetics proved to be a very important procedure in the verification of diagnosis of different mutations. The authors also discuss the problem of dietary treatment duration in PKU. In our opinion the hypophenyloalanine diet regimen in girls, should not be discontinued during adolescence, since there is the problem of maternal PKU and the possibility of foetal damage. The results of our own investigations of maternal PKU are discussed. The significance of mass-screening for galactosemia is still under discussion. In our opinion, mass-screening for galactosemia is not useful and we have discontinued it. Selective screening has been started combined with molecular genetic studies in high risk families. In the future, we plan to prepare guidelines on the principles of diagnosis and treatment of galactosemia in children and women in the reproductive age. Mass-screening for cystic fibrosis is also still under discussion. The results of the early screening programmes were not satisfactory and the tests were discontinued. In 1998, after reorganisation of the whole system, CF screening, using tripsin-radioimmune assays, was started again. The new screening programme is combined with molecular genetic investigation of different mutations. It is still too early to assess the importance and success of this CF mass-screening programme. We decided to discontinue the screening for homocystinuria, histidinemia, tyrosinemia, leucinosis and for neuroblastoma, since these programmes did not comply with criteria of mass-screening. In 1997, major reorganisation of screening programmes for inborn errors of metabolism, at NRIMC, was undertaken. The Guthrie test for PKU was changed to a quantitative colorimetric method. The immuno-luminometric method is used for TSH estimation. The whole system is based on complete computer control of all the steps of screening, from blood sampling on filter paper until the final diagnosis. The advantages of this modern system of organisation of the screening programme are discussed.

The aim of present study was to evaluate the effectiveness of screening program for early detection of some metabolic errors in newborn population. The examinations included: early diagnostic of some amino acids and carbohydrates disturbances, cystic fibrosis and congenital hypothyreosis. Guthrie test and multidirectional urine screening test were used for the diagnostics of inborn errors in amino acids metabolism. Guthrie test for phenylalanine proved its high effectiveness and taking into account the relatively high frequency of phenylketonuria in our population this screening has been introduced as obligatory. The evaluation of pilot screening for tyrosinemia, homocystinuria and histidinemia in spite of no objections as to the tests themselves proved low frequency of these disorders in our country, sofar these tests have been abandoned. Multidirectional urine screening carried out in 6-8 weeks old infants allows for follow up control for some aminoacidopathies, and also for the detection of some transport metabolism and other metabolic errors. There is no doubt that screening tests for galactosemia should be carried out because of severe course of the disease and good results of its treatment. Problem to be discussed is the choice of screening procedure and age at which it should be performed. Cystic fibrosis being one of the most common disease in the group of metabolic disorders needs to be screened, because the detection allows for early introduction of complex palliative treatment. The comparative evaluation of three meconium tests for cystic fibrosis revealed dry paper meconium test to be the most useful and following to organize central screening center. Skin chloride system being fast and easy test is too expensive to be introduced as mass screening. Results of pilot screening study for congenital hypothyreosis point out the necessity for the mass diagnostic of this disorders. Choice of the test however is connected with economical aspects of the screening procedure.