Cognitive and behavioral impairment in mild hyperphenylalaninemia. Turk J Pediatr 2018; 60: 617-624.As elevated phenylalanine (Phe) is detrimental to brain functions, determining a safe upper limit of blood Phe is important for initiation of treatment plans and setting Phe targets in hyperphenlalaninemic patients. It is accepted that Phe levels below 360 μmol/L does not impair brain function and hence does not require treatment. Therefore, we aimed to compare cognitive functions and attention-related problems among healthy children and untreated patients with hyperphenylalaninemia (HPA). This study included 41 hyperphenylalaninemic patients ("all HPA group") aged 6-16 years with untreated blood Phe between 240 and 600 μmol/L and 29 healthy controls. "All HPA group" was further divided into 2 subgroups according to their lifetime median blood Phe levels as "Phe 360-600 μmol/L" and "Phe 240-360 μmol/L" groups. Wechsler Intelligence Scale for Children-IV (WISC-IV), Conners' Continuous Performance Test (CPT), Strength and Difficulties Questionnaire (SDQ) and Schedule for Affective Disorders and Schizophrenia for School-Age Children: Present and Lifetime Version (K-SADS-PL) were performed as a comprehensive neurocognitive, attention and behavioral assessment. The study illustrated that "all HPA" patients had significantly lower scores on all WISC-IV indexes compared to controls, except for Working Memory. Both "Phe 360-600 μmol/L" and "Phe 240-360 μmol/L" subgroups had lower Full Scale intelligence quotient (IQ) and Verbal Comprehension scores compared to controls. "All HPA" patients also had longer reaction times and more peer problems than controls, indicating attention deficits and behavioral problems. Since the results demonstrated that children with untreated Phe levels between 240-360 μmol/L are at higher risk for cognitive and attention-related problems, lowering the "safe" upper Phe level should be considered.

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Background. Phenylketonuria (PKU) is an inherited disorder of amino acid metabolism, the treatment of which often requires a special diet to prevent adverse neuropsychiatric outcomes. In the COVID-19 pandemic, which has had a substantial effect on the whole world since the beginning of 2020, PKU patients represent a vulnerable population because they may be dependent on special nutritional products, have limited access to routine care and display increased levels of anxiety. Methods. For this reason, an online questionnaire assessing the anxiety levels and various personal opinions and practices regarding the pandemic was sent to the PKU patients managed at our clinic, who were 12 years of age or older. Ninety-eight patients responded to the questionnaire. Median age of the participants was 19 years. Results. Most patients were compliant with the hygiene and social distancing recommendations regarding the spread of COVID-19. Of the patients, 61.2% felt more anxious since the pandemic. The most common concern was the possibility of not being able to obtain special nutritional products (58.2%). Anxiety level was significantly higher in females. Conclusions. These data suggest that food security is an important issue of concern in PKU patients. In line with the changing world after the pandemic, different strategies should be considered in the management of patients with inborn errors of metabolism, including PKU.