Background: Hyperphenylalaninemia (HPA) is defined as blood phenylalanine (Phe) levels exceeding the normal values (>120 μmol/L or >2 mg/dL) and is caused by a deficiency in the enzyme phenylalanine hydroxylase (PAH). The widespread screening of Phe levels in newborn screening programs has led to a very high number of patients with HPA. Methods: The samples were collected at various ages, not at the point of diagnosis. Nine pterin derivatives, including isoxanthopterin, sepiapterin, xanthopterin, primapterin, biopterin, neopterin, 7,8-dihydrobiopterin, 7,8-dihydroneopterin, and tetrahydrobiopterin (BH4), were analyzed in different HPA classes in serum, dried blood spots (DBS), and urine samples. A total of 18 patients, including six classical phenylketonuria (PKU), eight BH4-responsive PKU, and four mild HPA patients, were included in the study. Results: Among the nine pterin derivatives measured, a significant increase was observed in the levels of isoxanthopterin, biopterin, and 7,8-dihydrobiopterin in serum, dried blood spots (DBS), and urine samples of patients with HPA compared to the control group. However, elevations in isoxanthopterin, biopterin, and 7,8-dihydrobiopterin were observed in all HPA groups, although the extent of elevation varied among the different disease groups. There were also significant differences between HPA subgroups among these high values. Conclusion: In this study, it might be suggested that pterin profiling shows promising potential for its effective utilization in the differential diagnosis of HPA. Pterin profiling demonstrated its efficacy in accurately categorizing patients into distinct subtypes. This approach offers several notable advantages, including the ability to simultaneously screen multiple HPA subtypes through a single test, establish disease decision limits for pterins, shorten the time required for HPA differential diagnosis, reduce the risk of misdiagnosis, and increase overall diagnostic accuracy. This study is the most comprehensive study examining the association between HPA pterin in the literature. In our study, samples obtained from BH4-responsive PKU patients were on treatment. This may have affected the results. Preliminary findings on pterin profiles may need to be replicated in a prospective cohort of samples collected at the time of diagnosis to confirm the results.

Metabolism is the name given to all of the chemical reactions in the cell involving thousands of proteins, including enzymes, receptors, and transporters. Inborn errors of metabolism (IEM) are caused by defects in the production and breakdown of proteins, fats, and carbohydrates. Micro ribonucleic acids (miRNAs) are short non-coding RNA molecules, ⁓19–25 nucleotides long, hairpin-shaped, produced from DNA. They play key roles in regulating gene expression of target mRNAs at both transcriptional and post-transcriptional levels. Altered expression of miRNAs has emerged as an additional molecular mechanism implicated in the pathogenesis of many diseases, this altered miRNA expression is also present in inherited metabolic diseases. A single miRNA can regulate targets associated with similar cellular processes and pathways, making miRNAs powerful therapeutics to restore the impaired cellular functions seen in disease phenotypes by enhancing the cellular response. Although the miRNA research field has advanced significantly in recent years, studies in IEM are still limited. Further research on miRNA expression specifically related to IEM may allow the identification of new biomarkers for the diagnosis, progression, and prognosis of diseases. In this review, the literature studies between miRNAs and IEMs, diagnosis, prognosis, follow-up, and treatment possibilities of miRNAs were analyzed. We present recent advances on miRNAs in IEM and an overview of current miRNA therapeutics for the clinic.

Objective: Coronavirus disease 2019 (COVID-19) infection is seen in all age groups, and its symptoms are very variable. The course of the disease can be asymptomatic or mortal. In pediatric patients, vitamin D is thought to be protective against (COVID-19) with its immunomodulator, antiviral, anti-inflammatory, and epithelial integrity properties. Our aim is to investigate the relationship between (COVID-19) infection and vitamin D level. Materials and Methods: We included (COVID-19) patients between 1 month and 18 years of age and healthy control groups. We compared epidemiological, clinical, laboratory, and imaging findings in patients. Results: One hundred forty-nine patients were evaluated in our study. Seventy-three (49%) of them were (COVID-19)-positive patients and 76 (51%) of them were healthy control group. The mean 25(OH)-D vitamin level was 15.80 ng/mL (5‐41.56) in (COVID-19) patients and 21.51 ng/mL (5-69.80) in the control group. Vitamin D level was shown to be statistically significantly lower in coronavirus disease 2019 patients (P < .001). It was observed that myalgia was more common in patients with low 25(OH)-D levels (P < .048). Conclusion: Our study is one of the rare studies examining the relationship between (COVID19) and 25(OH)-D vitamins in the pediatric age group. Children with (COVID-19) have a lower 25(OH)-D vitamin level than the control group. Cite this article as: Bayrak H, Öztürk D, Bolat A, Ünay B. Association between vitamin D levels and COVID-19 Infection in children: A case-control study. Turk Arch Pediatr. 2023;58(3):250-255.

Introduction: Mutations in the RMND1 gene that cause defects in the mitochondrial respiratory chain result in a highly variable phenotypic presentation. The protein required for meiotic nuclear division 1 homolog (RMND1) is localized to the inner mitochondrial membrane and is encoded by the nuclear genome. Case Presentation: We report a new patient from a consanguineous family who was severely affected by a previously described combined oxidative phosphorylation deficiency 11 and was treated rapidly due to early diagnosis. Methods: We also included patients with RMND1 mutation in the literature. We analyzed the epidemiological, clinical, laboratory, and genetic data of a total of 49 patients (98 alleles) in the literature, including our patient. We summarized all previously published patients and focused on the importance of early diagnosis. Results: The most common variant in patients with RMND1 mutation was c.713A>G (p.Asn238Ser). Mortality was significantly lower in patients with homozygous and compound heterozygous c.713A>G (p.Asn238Ser) mutations (p < 0.001). The second most common mutation was c1349G>C (p.*450Serext*31), which was reported in 11 patients (22.4%). Cardiac involvement and mortality were more common in patients with homozygous c.1349G>C (p.*450Serext*32) mutation (p = 0.008 and 0.008, respectively). Conclusion: In this study, the effect of cardiac involvement on mortality in RMND1 mutation was shown for the first time. We reported that mortality was lower in the c.713A>G (p.Asn238Ser) mutation. Furthermore, mortality was more common in the c.1349G>C (p.*450Serext*32) mutation. These findings have not been previously reported in the literature. They are reported for the first time in this study.

Introduction: Nonketotic hyperglycinemia (NKH) is a rare, autosomal recessive-inherited disorder of amino acid metabolism known as glycine encephalopathy. Clinical manifestations arise because of the enzyme deficiency involved in glycine degradation. Currently, no effective treatment exists to alter the prognosis of NKH; available therapies focus primarily on reducing glycine accumulation in the body. MicroRNAs (miRNAs) are small noncoding RNAs that function as transcriptional and post-transcriptional regulators of gene expression. Here, we report the comparative profiling of small RNA sequencing (RNA-seq) data generated from clinical samples diagnosed with a specific condition. Methods: We identified miRNAs using miRNA-seq with samples obtained from three NKH patients, five individuals with heterozygous variants in NKH genes, and seven control cases. Utilising pathways from the PubChem database, we identified NKH-related pathways and used bioinformatics tools for miRNA, pathway, and disease prediction. This was followed by Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses to enrich the predicted target genes of differentially expressed miRNAs based on miRNA-target interactions. Results: In our study, 10 known miRNAs were identified to be associated with NKH using at least two different tools. Our study is the first to demonstrate altered miRNA profiles in cases where the expression of AMT and GLDC genes is reduced. Conclusion: NKH is an ultrarare and difficult-to-diagnose disease. This study determines the miRNA-based biomarkers for early detection of NKH and provides a robust framework for advancing future experimental research and diagnostic strategies.

ESR: erythrocyte sedimentation rate; Hb: haemoglobin; HSP: Henoch-Schönlein purpura; WCC: white-cell count.