Professional activity, gender and disease-related emotions: The impact on parents' experiences in caring for children with phenylketonuria.

Introduction: Clinical management of rare diseases often fails to acknowledge the challenges faced by caregivers. Whilst management of phenylketonuria (PKU) may not be considered as dire as other conditions, most studies primarily concentrate on clinical issues, dietary adherence, or the quality of life of the PKU patients, leaving caregivers in the background. The aim of the study was to evaluate the psychosocial effects of PKU on family caregivers. Methods: Between October 30th, 2022 and February 28th, 2023, we collected data from caregivers of children with PKU using an anonymous, self-administered, computer-assisted online questionnaire. The survey was distributed among to patients during their regular visits to five Polish PKU treatment centers. Results: A total of 159 Polish caregivers of children with PKU completed the survey. This research shows that while women caregivers were more likely to be unemployed due to their responsibilities for childcare (50.3% compared to 0% for men), and men caregivers were more likely to be employed full-time (93.8% compared to 40.6% for women), the former reported higher emotional engagement in caregiving (88.1% vs 56.3% respectively). Significantly, unemployed mothers reported higher levels of loneliness, helplessness, and emotional control problems, and lacked psychological/emotional support more often than employed mothers. This research also shows a statistically significant positive correlation between mothers' education level and financial situation (p < 0.05) and education level and professional activity (p < 0.01). Additionally, a significant positive correlation was found between perceived financial situation and feeling of happiness (p < 0.001), and between financial situation and professional activity (p < 0.001). Finally, a significant positive correlation was observed between feeling of happiness and professional activity (p < 0.05). Conclusions: According to our findings, there is a link between subjective happiness, financial situation, and professional activity among female caregivers. The relationship between these factors goes beyond just the income earned from work. The results of our study imply that there could even be a therapeutic advantage for working mothers. It is crucial to recognize the emotional difficulties that employed mothers may experience while taking care of a child with PKU, and to provide them with the necessary assistance and resources to meet their needs. Additionally, our results may provide a foundation for redefining the support system for caregivers in Poland.

Management precautions for risk of obesity are necessary among infants with PKU carrying the rs113883650 variant of the LAT1 gene: A cross-sectional study.

Patients with phenylketonuria (PKU), an inborn error of phenylalanine metabolism, require consistent treatment to avoid the brain toxicity caused by hyperphenylalaninemia. The treatment consists of life-long use of a low-phenylalanine diet, which aims at decreasing hyperphenylalaninemia and maintaining blood phenylalanine concentration in a safe range. Problems with balancing diet can result in suboptimal treatment outcomes; however, recent findings suggest that genetic alteration of the transport of phenylalanine might result in an additional health burden. We assessed the effect of a common variant (rs113883650) of the LAT1(SLC7A5) gene, which encodes the main transmembrane phenylalanine transporter, on the development of overweight in 54 infants with PKU who received standard therapy and adhered well to therapeutic prescriptions, and in 55 infants with a milder disease form-the so-called mild hyperphenylalaninemia (MHP), which does not require treatment. We found that infants with PKU-carriers of the rs113883650 variant had significantly higher Body Mass Index (BMI) at 1 year compared to PKU infants without the variant (mean BMI Z-Score of +1.15 SD vs -0.15 SD, respectively; t(52) = 5.25, p = 0.00005). Conversely, no significant BMI differences were detected in the subgroups of infants with MHP (t(53) = 1.15, p = 0.25). Additionally, high BMI in infants with PKU-carriers of the rs113883650 variant positively correlated with high variability of their blood phenylalanine levels (r(52) = 0.42, p = 0.002). It should be noted that this is an observational study, which does not determine causation. Nevertheless, our findings show that the rs113883650 variant of the LAT1 gene may be a risk factor for overweight in properly treated infants with PKU. Management precautions should be taken to prevent the development of overweight and obesity.

Phenylketonuria Patients' and Their Caregivers' Perception of the Pandemic Lockdown: The Results of a National Online Survey.

The first pandemic lockdown dramatically impacted many aspects of everyday life, including healthcare systems. The purpose of this study was to identify problems of patients with phenylketonuria (PKU) and their parents/caregivers during that time. We aimed to analyse potential differences in the self-reported compliance and characteristics of contacts with a doctor/dietitian before and during the pandemic lockdown and the perception of access to special food and opinions on remote contacts between a particular group of respondents. All participants (n = 614) were asked to complete an online questionnaire that consisted of 31 questions on pandemic-related events and circumstances which may have directly or indirectly impacted health and treatment. The people who completed the survey were divided into three groups: parents of PKU children (n = 403), parents of PKU adults (n = 58) and PKU patients older than 16 years (n = 153). The differences among the three analysed groups were found in the number of contacts, the way of contacting a doctor/dietitian during the pandemic and satisfaction with remote contact. Caregivers of children with PKU reported better therapy compliance, more frequent contacts with specialists and more satisfaction with remote visits than adult patients. We also observed a relationship between satisfaction from remote contact and self-reported frequency of contacts with a doctor/dietitian, as well as a relationship between satisfaction from remote contact and recommended blood Phe levels reported by both patients and caregivers. Travel time exceeding three hours from the respondents' location to their doctor was associated with higher odds of their recognition of remote contact as a method of PKU treatment only in the group of caregivers. In the caregiver groups, the reported worse access to low-Phe products during the lockdown was linked to the perceived difficulty of maintaining the diet. However, such a relationship was not found among patients. In conclusion, significant differences in the perception of the pandemic lockdown and its impact on health and treatment-related issues were found.

The Impact of the First 2020 COVID-19 Lockdown on the Metabolic Control of Patients with Phenylketonuria.

The present study assessed patients' metabolic control of phenylketonuria (PKU) during the first 2020 COVID-19 lockdown in Poland. Blood (phenylalanine) Phe results of the tests of 535 patients, performed in 2019 and in the first months of 2020, were analysed. The six-week lockdown period was compared to the preceding six-week period as well as to the two corresponding periods of 2019 (three non-lockdown periods). More patients failed to perform Phe tests in the lockdown period (32.7%) than in non-lockdown periods (15.6%, 15.1%, 17.2%; p < 0.001 for all). The median Phe levels for those patients who performed testing in all the four periods did not differ between periods. However, these patients tended to perform only one test during the lockdown (ORs: 1.43 to 1.60; 95% CI: from 1.01-2.04 to 1.11-2.30, p-value 0.02 to 0.005). Patients who did not take blood during the lockdown (46.7%) performed significantly fewer blood tests in the remaining periods (median : 1 <0-1> vs. 2 <1-4>; p < 0.001). In conclusion, direct assessment of patients' compliance based upon Phe levels during the pandemic lockdown was not possible. Pre-pandemic non-compliant patients frequently failed to perform the test during the lockdown, whereas the previously compliant ones were more likely to perform only one test. This strongly suggests that metabolic control might have worsened.

The Impact of the COVID-19 Pandemic on the Perception of Health and Treatment-Related Issues among Patients with Phenylketonuria in Poland-The Results of a National Online Survey.

There is agreement that the pandemic has affected the healthcare system and behaviour of patients. This study aims to identify problems encountered by patients with phenylketonuria (PKU) and their parents/caregivers during the six-week pandemic lockdown in Poland (15 March to 30 April 2020). To determine the factors that influenced health and treatment-related issues, as well as the respondents' perception of the impact of the pandemic, study participants were asked to complete a non-validated online questionnaire comprising 31 questions (including 27 single-choice, two multiple-choice and two open-ended ones). A total of 571 patients or their parents completed the questionnaire, with 9.5% of respondents not performing any blood phenylalanine (Phe) test in the analysed period, 21.3% declaring a blood Phe increase, and 15.3% a decrease. Increased problems in contacting the doctor or dietitian were reported by 26.1% of subjects, whereas 39.3% of them felt restricted access to dietary products. Most (63.4%) participants were satisfied with remote contact with their PKU clinic. Better compliance was associated with higher odds of acceptance of remote contact and of reporting fewer problems with contacting the doctor, and with lower odds of missing Phe testing. Self-reported high stress was associated with higher odds of reporting the limited availability of low-Phe products and Phe-free formulas, as well as with increased Phe concentrations and non-PKU-related health problems. These patients also had poor dietary compliance and experienced more problems in contacting specialists. Health and treatment-related problems experienced during the pandemic lockdown were related to a higher intensity of stress in patient's family and worse therapy compliance before the pandemic. Previous experience of remote visits resulted in a better perception of this method of contact. It seems that this form of communication should be popularized and improved to increase therapy effectiveness in case of different limitations in the future. Special attention should be paid to vulnerable patients who may be at extra risk when the provision of standard care is affected.

Carriership of the rs113883650/rs2287120 haplotype of the SLC7A5 (LAT1) gene increases the risk of obesity in infants with phenylketonuria.

PURPOSE: Phenylketonuria (PKU) can be effectively treated with the use of a low-phenylalanine diet. However, some patients become overweight despite proper dietary treatment. We hypothesized that this phenomenon could be explained by the presence of specific variants within the genes involved in phenylalanine transport or in the phenylalanine transamination/oxygenation pathway. METHODS: We selected a clinically homogenous group of 100 infants with PKU and assessed their growth patterns in the context of dietary phenylalanine tolerance. Next, within the sample, we performed exome sequencing and assessed a potential relationship between the observed phenotypical variability and the presence of structural variants in a priori selected genes of interest. RESULTS: We detected a highly significant association between overweight and carriership of the rs113883650/rs2287120 haplotype of the SLC7A5 (LAT1) gene, which encodes the main transmembrane transporter of large neutral amino acids and of thyroid hormones. CONCLUSIONS: Our findings suggest a pharmacogenetic effect of the relatively common rs113883650/rs2287120 haplotype of the SLC7A5 gene. This can have practical implications for patients with PKU, since treatment protocols need to be reassessed to better prevent overweight in the carriers of the above variant.

Untreated PKU Patients without Intellectual Disability: What Do They Teach Us?

Phenylketonuria (PKU) management is aimed at preventing neurocognitive and psychosocial dysfunction by keeping plasma phenylalanine concentrations within the recommended target range. It can be questioned, however, whether universal plasma phenylalanine target levels would result in optimal neurocognitive outcomes for all patients, as similar plasma phenylalanine concentrations do not seem to have the same consequences to the brain for each PKU individual. To better understand the inter-individual differences in brain vulnerability to high plasma phenylalanine concentrations, we aimed to identify untreated and/or late-diagnosed PKU patients with near-normal outcome, despite high plasma phenylalanine concentrations, who are still alive. In total, we identified 16 such cases. While intellectual functioning in these patients was relatively unaffected, they often did present other neurological, psychological, and behavioral problems. Thereby, these "unusual" PKU patients show that the classical symptomatology of untreated or late-treated PKU may have to be rewritten. Moreover, these cases show that a lack of intellectual dysfunction despite high plasma phenylalanine concentrations does not necessarily imply that these high phenylalanine concentrations have not been toxic to the brain. Also, these cases may suggest that different mechanisms are involved in PKU pathophysiology, of which the relative importance seems to differ between patients and possibly also with increasing age. Further research should aim to better distinguish PKU patients with respect to their cerebral effects to high plasma phenylalanine concentrations.

Can untreated PKU patients escape from intellectual disability? A systematic review.

BACKGROUND: Phenylketonuria (PKU) is often considered as the classical example of a genetic disorder in which severe symptoms can nowadays successfully be prevented by early diagnosis and treatment. In contrast, untreated or late-treated PKU is known to result in severe intellectual disability, seizures, and behavioral disturbances. Rarely, however, untreated or late-diagnosed PKU patients with high plasma phenylalanine concentrations have been reported to escape from intellectual disability. The present study aimed to review published cases of such PKU patients. METHODS: To this purpose, we conducted a literature search in PubMed and EMBASE up to 8th of September 2017 to identify cases with 1) PKU diagnosis and start of treatment after 7 years of age; 2) untreated plasma phenylalanine concentrations ≥1200 µmol/l; and 3) IQ ≥80. Literature search, checking reference lists, selection of articles, and extraction of data were performed by two independent researchers. RESULTS: In total, we identified 59 published cases of patients with late-diagnosed PKU and unexpected favorable outcome who met the inclusion criteria. Although all investigated patients had intellectual functioning within the normal range, at least 19 showed other neurological, psychological, and/or behavioral symptoms. CONCLUSIONS: Based on the present findings, the classical symptomatology of untreated or late-treated PKU may need to be rewritten, not only in the sense that intellectual dysfunction is not obligatory, but also in the sense that intellectual functioning does not (re)present the full picture of brain damage due to high plasma phenylalanine concentrations. Further identification of such patients and additional analyses are necessary to better understand these differences between PKU patients.

Blood phenylalanine instability strongly correlates with anxiety in phenylketonuria.

We assessed the relationship between anxiety and long-term metabolic control in adolescents with phenylketonuria (PKU). We used a standardized psychological test to measure anxiety level and analyzed lifelong blood phenylalanine stability in a selected group of 25 PKU teenagers with treatment adherence problems. We demonstrated significant correlations of anxiety with variability of blood phenylalanine concentrations and with severity of hyperphenylalaninemia. Avoiding blood phenylalanine fluctuations in childhood can probably reduce anxiety in PKU adolescents.

The Use of d2 and Benton Tests for Assessment of Attention Deficits and Visual Memory in Teenagers with Phenylketonuria.

Hyperphenylalaninemia-related, subtle deficits of attention and of working memory are often reported in adolescents with phenylketonuria. Focused neuropsychological tests can be used to detect such deficits and to confirm the presence of poor metabolic control in the periods between routine blood phenylalanine tests, which are rarely performed in many patients from this age group due to their low treatment adherence.We assessed the practical value of the d2 test of attention and of the Benton visual retention test for identification of teenagers, who have a high risk of brain dysfunction due to hyperphenylalaninemia. We analyzed the correlation between neuropsychological test scores achieved by 30 patients and their blood phenylalanine profiles since the neonatal period.We observed strong correlation between the Concentration Performance scores on the d2 test and the quality of metabolic control within last month prior to the follow-up visit in the outpatient clinic (r = -0.72; p = 0.0003). The mean z-score was significantly higher in patients with good metabolic control than in those with poorly controlled hyperphenylalaninemia (0.44 vs. -1.12; p = 0.00002). On contrary, the results of the Benton visual retention test did not correlate significantly with the individual blood phenylalanine profiles.We believe that neuropsychological assessment should be used in adolescents with phenylketonuria on a regular basis in order to increase the self-awareness in these patients and, consequently, to increase their treatment adherence and safety. The d2 test can be effectively used for detection of attention deficits and seems to be a valuable supplementary procedure for routine follow-up.

Dynamics of hyperphenylalaninemia and intellectual outcome in teenagers with phenylketonuria.

Insufficient treatment adherence after early childhood is frequently observed in patients with phenylketonuria. Assessment of these individuals' long-term metabolic control could enable early detection of the risk of intellectual deterioration resulting from high blood phenylalanine concentration. However, the predictive value of specific parameters related to individual dynamics of hyperphenylalaninemia is not clear. Here, we assessed the impact of blood phenylalanine fluctuations during the first 12 years of life on cognitive outcome in early and continuously treated teenagers with phenylketonuria. We have analyzed a total of 5141 results of blood phenylalanine measurements in 32 patients. The phenylalanine levels of these patients were usually acceptable during their early childhood, but the control of hyperphenylalaninemia worsened and the average treatment adherence dropped to 40% during the late primary school. Our analysis revealed a strong association between the Wechsler intelligence verbal scores and the mean of the yearly means of phenylalanine concentrations (r=-0.62). The correlations of IQ scores with median phenylalanine concentrations and the variability of blood phenylalanine levels gave weaker associations. The Wechsler verbal scores were also strongly correlated with the treatment adherence level during preschool and late primary school (r=0.61 and 0.72). The mean of the yearly means of blood phenylalanine concentrations appears to be a better predictor of cognitive outcome in children with phenylketonuria than other parameters related to phenylalanine fluctuations. The percentage of acceptable phenylalanine levels below 50-60% should be regarded as a "red flag" due to the risk of intellectual deterioration in patients.

Phenylketonuria patients' and their parents' knowledge and attitudes to the daily diet - multi-centre study.

BACKGROUND: The aim of the study was to assess both patients' and their parents' knowledge of phenylketonuria (PKU) treatment and compliance with PKU diet. METHODS: The study included 173 PKU patients aged 10-19 and 110 parents of PKU children who were enrolled in the study on the basis of questionnaire data. The study also included 45 patients aged ≥20. RESULTS: Our study demonstrated that only 45% (n = 74) of PKU patients knew daily Phe intake recommendations, 27% of patients (n = 41) knew the Phe content in a minimum of three out of four researched food products. Patients' knowledge concerning Phe intake (p = 0.0181) and the knowledge of selected food products (p = 0.041819) improved with age. We did not establish such a correlation in the group of PKU children's parents. Approximately 31% of patients and 22% of parents reported helplessness, which increased with the child's age, associated with the necessity to adhere to the diet; 30% of patients reported feeling ashamed of the fact that they could not eat all food products. Regardless of age, children were more likely than parents to report helplessness (p = 0.032005). Among patients, 41.40% declared that they would wish to select products unassisted but their parents did not permit them to do so. The question of whether parents teach children self-reliance in meal preparation was answered affirmatively by 98% of parents and only 81% of children (p = 0.0001). CONCLUSION: Our data demonstrated that parents' and children's knowledge concerning treatment recommendations and food products does not have a direct impact on attitude to the PKU diet. Limiting children's independence in meal selection, growing helplessness in the face of dietary adherence and shame resulting from the necessity to follow a different diet observed in PKU families are responsible for shaping and perpetuating a consistently negative attitude to the diet. The care of PKU paediatric patients requires consistent, long-term family and individual therapy which may counteract the effects of learned helplessness. In regard to the educational effort, a good parent-child relationship as well as the teaching of behaviours motivating patients to comply with the diet are of great importance.

Phenylketonuria patients' and their parents' acceptance of the disease: multi-centre study.

PURPOSE: Phenylketonuria (PKU) still poses a therapeutic challenge for patients and medical professionals. The aim of the study was to assess both patients' and their parents' acceptance of the disease. METHODS: The study included 218 PKU patients and 178 parents of PKU children who were enrolled in the study on the basis of questionnaire data. RESULTS: Regarding attitude towards the disease, our study demonstrated that 63 (28.9 %) PKU patients did not accept the disease. Patients who found accepting the disease difficult, more frequently perceived themselves as inferior/different in comparison with their peers. In total, 36 % of patients did not want their friends to be aware of their condition, while only 18 % of parents believed that their children's peers should not know about their disease. In total, 42 % of parents wanted to talk to other parents of PKU children and only 13 % to a doctor. Only 20 % of patients saw the need to discuss their condition with a doctor. In total, 8 % of children, regardless of age, and 14 % of parents preferred to talk to a psychologist. CONCLUSION: Our data demonstrated that disease acceptance played an essential role in patients' social integration. The study also indicated the need to overcome communication barriers between patients and their healthy peers and for patients to find the courage to be open about the disease. The importance of support groups for PKU families and the significance of strict cooperation between patients and their families with PKU treatment teams were also revealed.

Molecular genetics of PKU in Poland and potential impact of mutations on BH4 responsiveness.

Tetrahydrobiopterin (BH4) has been recently approved as a treatment of patients with phenylketonuria. However, as a confirmation of BH4-responsiveness, it might require a very expensive trial treatment with BH4 or prolonged BH4-loading procedures. The selection of patients eligible for BH4-therapy by means of genotyping of the PAH gene mutations may be recommended as a complementary approach. A population-wide genotyping study was carried out in 1286 Polish phenyloketonuria-patients. The aim was to estimate the BH4 demand and to cover prospectively the treatment by a National Health Fund. A total of 95 types of mutations were identified. Genetic variants corresponding with probable BH4-responsiveness were found in 28.2% of cases. However, patients with mild or classical phenylketonuria who require continuous treatment accounted for 11.4% of the studied population only. Analysis of the published data shows similar percentage of the "BH4-responsive" variants of a PAH gene in patients from other countries of Eastern Europe. Therefore, it can be concluded, that the proportion of phenylketonuria-patients who could benefit from the use of BH4 reaches approximately 10% in the entire region.

Impact of lipophilic antioxidants and level of antibodies against oxidized low-density lipoprotein in Polish children with phenylketonuria.

The treatment of phenylketonuria (PKU) patients constitutes a phenylalanine (Phe) intake restriction in their diet, which is achieved by adding a special Phe-free amino acid mixture to the diet. It has been reported that this diet could have some micronutrient deficiency. Several authors have also reported an increased oxidative stress or impaired antioxidant status in human and experimental PKU. Our project assessed the concentrations of retinol, alpha-tocopherol, coenzyme Q10, and anti-oxidized low-density lipoprotein (ox-LDL) antibodies in PKU children's plasma. It was found that retinol concentration in PKU children remains within the norm despite a low intake. The lower plasma alpha-tocopherol concentration in PKU children compared with normal children was associated with the lower level of antibodies against ox-LDL. This raises the question whether higher than observed circulatory alpha-tocopherol is indeed beneficial to lower plasma ox-LDL levels. Further studies are needed to explain the genetic factor in PKU patients (e.g., CD36/FAT polymorphism gene). The open clinical question is whether daily supplementation of alpha-tocopherol changes the PKU patients' level of antibodies against ox-LDL.

[The maternal phenylketonuria syndrom--still current problem]. / Zespól fenyloketonurii matczynej--problem nadal aktualny.

UNLABELLED: Phenylketonuria (OMIM 261600) is a congenital genetically conditioned error of metabolism phenylalanine to tyrosine. Being untreated or insufficiently treated phenylketonuria (PKU) sometimes leads to irreversible damage of mielin. Similarly, high phenylalanine concentration in the blood of pregnant woman with PKU exert the teratogenic effect on growing and developing foetus (in the majority of cases being the carrier of PKU), which leads to appearance of maternal phenylketonuria syndrom (MPKU syndrom). The features of MPKU syndrome consist: low weight at birth, the congenital heart defects, digestive tract defects, osseous arrangements, microcephaly, handicap of intellectual development. Spontaneous miscarriages at pregnant women with PKU are more often. THE AIM OF WORK: the evaluation of influence hyperphenylalaninemia of pregnant woman with PKU on her foetus, depending on the metabolic control in the pre- and postconception period. MATERIAL AND METHOD: under the care of Outpatient Metabolic Clinic of University Children's Hospital in Cracow remain 430 patients aged from 0 to 56 years with hyperphenylalaninemia. In the register of Outpatient Metabolic Clinic there are the data about 50 pregnancies of 21 women with hyperphylalaninemia (from mild hyperphenylalaninemia to classic PKU). Only 10 pregnancies were planned - the low-phenylalanine diet was obligatory introduced 3 months before conception and was applied throughout the whole period of pregnancy in order to maintain the levels of phenylalanine in the range of 2 to 6 mg/dl. One pregnancy finished with spontaneous miscarriage, the other 9- the birth of healthy offspring. By contrast, out of 40 unplanned pregnancies 8 ended in spontaneous miscarriage, and of the remaining 32 unplanned pregnancies 33 children were born: 24 (75%) newborns with the maternal PKU features, 1 child died during thel-st year of life, 3 have the lack of any data, and only 5 (15.6%) children were born clinically healthy (1 twin birth). Among the children with maternal PKU syndrome: microcephaly was diagnosed in 17 cases, congenital heart defect and microcephaly in 6 children, and microcephaly and the anal atresia in 1 child. Among the children, born from unplanned pregnancies, there are two (twins), whose mother from the 6 week of gestation had returned to applying diet (average phe levels 6.37 mg/dl); two children of mothers who were conducting the therapeutic implemented since 18-th and 32-th weeks of gestation (average phe 7.5 mg/dl) (there is the lack of detailed data about these children, because the women are never reported to our Outpatient Clinic), and one child, whose mother raised and began the therapy from 12-th week of gestation (average phe levels 10.37 mg/dl), who presents the features of ADHD syndrome. CONCLUSIONS: 1. All pregnancies of women with hyperphenylalaninemia should be planned to avoid the complications in the form of maternal PKU syndrom. 2. It is essential to educate the women with PKU and their families about the problems concerning maternal PKU. 3. It is also necessary to inform pediatricians, family physicians and gynaecologists-obstetricians about the features of maternal PKU syndrom.

[Did the change of technique of screening investigations influence on improvement of test credibility in recognizing and differentiating diagnostics of hiperphenylalaninemias?]. / Czy zmiana techniki badan przesiewowych wplynela na poprawe wiarygodnosci testu w rozpoznawaniu i diagnostyce róznicowej hiperfenyloalaninemii?

UNLABELLED: The phenylketonuria (PKU)/hyperphenylalaninemia (HPA) it is the most frequent inborn genetically conditioned error of metabolism of amino acids. It's occurrence in Polish population was estimated on the level 1:7.000 - 8.500. A. Folling was the first who described the phenylketonuria in 1934. It's diagnosed by neonatal screening, which was initiated in 1963 by prof. R. Guthrie. MATERIAL: since 1985 till 2007 1,172,310 newborns investigated by the neonatal screening proceeding by the Laboratory of Screening and Inborn Errors of Metabolism in Cracow. METHOD: in the years 1985-1998 the phenylalanine concentration in drop of blood on the blotting-paper was measured with half-quantitative Guthrie method. However after 1999 the colorimetric quantitative method measurement of phenylalanine concentration in capilar blood was introduced. It 2004 the cut-off value of phenylalanine in drop of blood on filter paper in neonatal screening investigation has was established below 3 mg/dl (till 2003 it was below 4mg/ dl). The blood had been taken from every newborn on filter paper Standard 903 between third and seventh day of the child's life. The verification of recognition in 1985-1988 was applied by Guthrie test, in 1989-2006 by the fluorymetric McCaman and Robins method, and since 2007 by colorimetric method. RESULTS: in 1985-1998 the group of 137 newborns was distinguished due to the newborn screening (1:4.204), the classic PKU was recognized at 96 (1:5.999), however in next years (after change of method) due to screening 186 (1:4.788) newborns were distinguished, the classic PKU was recognized at 94 (1:5.236) newborn children. The lowering the point of cut-off influenced on frequency recognizing mild HPA, which grew up from 1:25.909 to 1:12.720. In 2001 we verified the recognition at 51 of 93 women (data were have gained over from archive of Outpatient Department), who where identified by the neonatal screening in 1985-1998, and in the face of observed phenylalanine values (<10 mg/dl - mild HPA) did not require dietetic treatment, and they gave up with medical care gradually. With regard on possibility pronouncement the signs of maternal PKU at their offspring, we ask 45 of them to contact with our Outpatient Clinic again, but only 36 with different reasons answered, at 28 of them the phenylalanine concentration was raised: 2-4 mg/dl - in 1 patient; 4-6 mg/ dl - in 6 patients; 6-10 mg/dl - in 11 patients; 10-20 mg/dl - in 12 patients. With this reason at 19 women the low-phenylalanine diet had to be introduce. CONCLUSIONS: 1. Applied Guthrie test limited the individual differentiating diagnostics of HPA, which led to relinquishment of medical observation, especially in girls and young women, the birth the child with maternal PKU could be the result of that. 2. Introduction of colorimetric method improved the detecting of the mild PKU and hyperphenylalaninemia considerably.