Predictors of eventual requirement of phenylalanine-restricted diet in young infants with phenylalanine hydroxylase deficiency initially managed with sapropterin monotherapy.

BACKGROUND: Phenylalanine (Phe)-restricted diet is associated with lower quality of life for patients with phenylketonuria (PKU), and a concern for caregivers of recently-diagnosed infants. Sapropterin is an oral drug used as an alternative or adjunct to dietary treatment. We have observed that some of the young infants initially managed successfully with sapropterin monotherapy have required dietary treatment in long-term follow-up. We aimed to determine the baseline factors associated with future initiation of dietary treatment in these patients. METHODS: Data were obtained retrospectively from the medical records of 80 PKU patients started on sapropterin monotherapy before 3 months of age between 2011 and 2021. RESULTS: The patients were followed for a median of 3.9 years (Q1-Q3: 2.5-5.75 years). Sapropterin was tapered down and discontinued in 5 patients (6.3%) as their Phe levels remained below 360 µmol/L without treatment. Sapropterin monotherapy was sufficient in 62 patients (77.5%), while 13 (16.2%) required dietary treatment. Phe and tyrosine (Tyr) levels, and Phe:Tyr ratios differed significantly among the patients maintained on sapropterin monotherapy and those started on dietary treatment, but the Phe:Tyr ratio at diagnosis was the most important independent baseline variable (OR: 1.61, 95% CI: 1.15-2.27, p = 0.006), with Phe:Tyr ratio at diagnosis >5.25 associated with dietary treatment (sensitivity: 90.0%, specificity: 81.8%). Genotypic phenotype value (GPV), unavailable at baseline, was also associated with dietary treatment (median GPV 9.2 vs. 3.8, p = 0.006), but some genotypes were not specific to the final treatment modality. DISCUSSION: We propose that the Phe:Tyr ratio at diagnosis is an important indicator to predict dietary requirement in young infants initially managed with sapropterin monotherapy.

Expert Consensus on the Long-Term Effectiveness of Medical Nutrition Therapy and Its Impact on the Outcomes of Adults with Phenylketonuria.

Many adults with phenylketonuria (PKU) rely on medical nutrition therapy (MNT; low phenylalanine (Phe) diet with protein substitutes/medical foods) to maintain blood Phe concentrations within recommended ranges and prevent PKU-associated comorbidities. Despite disease detection through newborn screening and introduction of MNT as early as birth, adherence to MNT often deteriorates from childhood onwards, complicating the assessment of its effectiveness in the long term. Via a modified Delphi process, consensus (≥70% agreement) was sought on 19 statements among an international, multidisciplinary 13-member expert panel. After three iterative voting rounds, the panel achieved consensus on 17 statements related to the limitations of the long-term effectiveness of MNT (7), the burden of long-term reliance on MNT (4), and its potential long-term detrimental health effects (6). According to the expert panel, the effectiveness of MNT is limited in the long term, is associated with a high treatment burden, and demonstrates that adults with PKU are often unable to achieve metabolic control through dietary management alone, creating an unmet need in the adult PKU population.

Levodopa-refractory hyperprolactinemia and pituitary findings in inherited disorders of biogenic amine metabolism.

Elevated serum prolactin concentrations occur in inherited disorders of biogenic amine metabolism because dopamine deficiency leads to insufficient inhibition of prolactin secretion. This work from the International Working Group on Neurotransmitter Related Disorders (iNTD) presents the results of the first standardized study on levodopa-refractory hyperprolactinemia (LRHP; >1000 mU/L) and pituitary magnetic resonance imaging (MRI) abnormalities in patients with inherited disorders of biogenic amine metabolism. Twenty-six individuals had LRHP or abnormal pituitary findings on MRI. Tetrahydrobiopterin deficiencies were the most common diagnoses (n = 22). The median age at diagnosis of LRHP was 16 years (range: 2.5-30, 1st-3rd quartiles: 12.25-17 years). Twelve individuals (nine females) had symptoms attributed to hyperprolactinemia: menstruation-related abnormalities (n = 7), pubertal delay or arrest (n = 5), galactorrhea (n = 3), and decreased sexual functions (n = 2). MRI of the pituitary gland was obtained in 21 individuals; six had heterogeneity/hyperplasia of the gland, five had adenoma, and 10 had normal findings. Eleven individuals were treated with the dopamine agonist cabergoline, ameliorating the hyperprolactinemia-related symptoms in all those assessed. Routine monitoring of these symptoms together with prolactin concentrations, especially after the first decade of life, should be taken into consideration during follow-up evaluations. The potential of slow-release levodopa formulations and low-dose dopamine agonists as part of first-line therapy in the prevention and treatment of hyperprolactinemia should be investigated further in animal studies and human trials. This work adds hyperprolactinemia-related findings to the current knowledge of the phenotypic spectrum of inherited disorders of biogenic amine metabolism.

COVID-19 in inherited metabolic disorders: Clinical features and risk factors for disease severity.

BACKGROUND: Old age, obesity, and certain chronic conditions are among the risk factors for severe COVID-19. More information is needed on whether inherited metabolic disorders (IMD) confer risk of more severe COVID-19. We aimed to establish COVID-19 severity and associated risk factors in patients with IMD currently followed at a single metabolic center. METHODS: Among all IMD patients followed at a single metabolic referral center who had at least one clinic visit since 2018, those with accessible medical records were reviewed for SARS-CoV-2 tests. COVID-19 severity was classified according to the WHO recommendations, and IMD as per the international classification of IMD. RESULTS: Among the 1841 patients with IMD, 248 (13.5%) had tested positive for COVID-19, 223 of whom gave consent for inclusion in the study (131 children and 92 adults). Phenylalanine hydroxylase (48.4%) and biotinidase (12.1%) deficiencies were the most common diagnoses, followed by mucopolysaccharidoses (7.2%). 38.1% had comorbidities, such as neurologic disabilities (22%) or obesity (9.4%). The majority of COVID-19 episodes were asymptomatic (16.1%) or mild (77.6%), but 6 patients (2.7%) each had moderate and severe COVID-19, and two (0.9%) had critical COVID-19, both of whom died. 3 patients had an acute metabolic decompensation during the infection. Two children developed multisystem inflammatory syndrome (MIS-C). Long COVID symptoms were present in 25.2%. Presence of comorbidities was significantly associated with more severe COVID-19 in adults with IMD (p < 0.01), but not in children (p = 0.45). Compared to other categories of IMD, complex molecule degradation disorders were significantly associated with more severe COVID-19 in children (p < 0.01); such a significant IMD category distinction was not found in adults. DISCUSSION: This is the largest study on COVID-19 in IMD patients relying on real-word data and objective definitions, and not on merely expert opinions or physician surveys. COVID-19 severity and long COVID incidence in IMD are probably similar to the general population, and the risk of acute metabolic decompensation is not likely to be greater than that in other acute infections. Disease category (complex molecule degradation) in children, and comorbidities in adults may be associated with COVID-19 severity in IMD. Additionally, the first documented accounts of COVID-19 in 27 different IMD are recorded. The high occurrence of MIS-C may be coincidental, but warrants further study.

Efficacy of Tele-CO-OP in Children With Organic Acidemia: A Pilot Randomized Controlled Trial.

The objective of this study was to examine the efficacy of a 5-week, tele-CO-OP intervention in children with organic acidemia. Thirty-four children were randomly divided into intervention and control groups. While 17 received the home program, 17 received the CO-OP Approach with telehealth twice a week along with the home program. Children were assessed through the Canadian Occupational Performance Measure, Pediatric Evaluation of Disability Inventory, Child and Adolescent Scale of Participation, Kid-KINDL Questionnaire, and Assistance to Participate Scale. Between-group analyses show significant benefits (p < .05) for the CO-OP group compared with the control group on the Performance and Satisfaction scales of the Canadian Occupational Performance Measure, and on the total scores of the Pediatric Evaluation of Disability Inventory, Child and Adolescent Scale of Participation, KINDL, and the Assistance to Participate Scale. The findings are preliminary results of benefits as this is the first trial, and the CO-OP approach applied through telerehabilitation had positive effects on children with organic acidemia.

Successful management of rhabdomyolysis with triheptanoin in a child with severe long-chain 3-hydroxyacyl-coenzyme A dehydrogenase (LCHAD) deficiency.

Early-onset long-chain 3-hydroxyacyl-coenzyme A dehydrogenase (LCHAD) deficiency is a fatty acid ß-oxidation disorder with a poor prognosis. Triheptanoin, an anaplerotic oil with odd-chain fatty acids can improve the disease course. The female patient presented here was diagnosed at the age of 4 months, and treatment was started as fat restriction, frequent feeding, and standard medium-chain triglyceride supplementation. In follow-up, she had frequent rhabdomyolysis episodes (∼8 per year). At the age of six, she had 13 episodes in 6 months, and triheptanoin was started as part of a compassionate use program. Following unrelated hospital stays due to multisystem inflammatory syndrome in children and a bloodstream infection, she had only 3 rhabdomyolysis episodes, and hospitalized days decreased from 73 to 11 during her first year with triheptanoin. Triheptanoin drastically decreased the frequency and severity of rhabdomyolysis, but progression of retinopathy was not altered.

Vascular and structural analyses of retinal and choroidal alterations in Fabry disease: the effect of hyperreflective foci and retinal vascular tortuosity.

PURPOSE: To evaluate the effects of Fabry disease (FD) on the retinal microvasculature and choroidal vascular and structural characteristics. METHODS: This study included 10 patients with FD and 10 age-matched healthy controls. Binarized enhanced depth imaging optical coherence tomography (OCT) images were used to measure the total choroidal area, luminal area, and stromal area with ImageJ software. The choroidal vascularity index (CVI) was assessed. The vessel densities (VD) of the retinal capillary plexuses and foveal avascular zone (FAZ) area were measured with OCT-angiography. RESULTS: The most common anterior segment finding was cornea verticillata (60.0%) and the most frequent posterior segment finding was vascular tortuosity (50.0%). Intraretinal hyperreflective foci on B-scan OCT was observed in 50.0% of the cases. In Fabry cases, a linear mixed model with random intercept revealed that 1% change in CVI was related to -0.009 mm2 (p = .015) change in FAZ area and -0.047 mm change, (p = .024) in FAZ perimeter. In the presence of retinal vascular tortuosity, 1% change in CVI was related to -0.013 mm2 (p = .002) change in FAZ area and -0.052 mm change (p = .004) in FAZ perimeter. In the presence of hyperreflective foci, 1% change in CVI was related to -0.014 mm2 (p = .004) change in FAZ area and -0.064 mm change (p = .003) in FAZ perimeter. CONCLUSION: The significant negative associations between FAZ measurements and CVI suggest a possible interaction between the choroidal and retinal microvasculature of patients with FD. These alterations were more pronounced in the presence of hyperreflective foci and retinal vascular tortuosity.

Evaluation of sleep-disordered breathing and its relationship with respiratory parameters in children with mucopolysaccharidosis Type IVA and VI.

The aims of the study were to evaluate the prevalence of sleep-disordered breathing (SDB) by using polysomnography (PSG) in children with MPS IVA and MPS VI who underwent enzyme replacement therapy (ERT) and to analyze the effect on SDB of having upper airway surgery, pulmonary functions, and exercise capacity. A retrospective cross-sectional study was conducted on patients with MPS IVA (n:17) and MPS VI (n:11) aged under 19 years who underwent polysomnography. Descriptive and nonparametric analyses were performed for demographic, PSG, pulmonary function and exercise capacity variables. The frequency of sleep apnea in the study sample was 85.7% (24/28). Four patients (14.3%) had no sleep apnea, 15 (53.6%) had mild, and nine (32.1%) had moderate-to-severe sleep apnea. Two patients (7.1%) had central sleep apnea and 22 had obstructive sleep apnea (OSA) (78.6%). Forced expiratory volume in 1 s (FEV1) and forced vital capacity (FVC) were negatively correlated to apnea-hypopnea index (AHI) (r = -0.594, p = .009; r = -0.636, p = .005, respectively). Despite ERT and previous upper airway surgery, the prevalence of OSA was high in patients with MPS IVA-MPS IV, emphasizing the importance of PSG screening for sleep disorders. Pulmonary function tests may be useful for predicting sleep apnea in patients with MPS IVA and MPS VI.

Caring for a Child with Phenylketonuria: Parental Experiences from a Eurasian Country.

OBJECTIVES: Phenylketonuria (PKU) and mild hyperphenylalaninemia (HPA) are characterized by increased blood phenylalanine concentrations varying from mild to severe. Management of PKU was reported to be time consuming and burdensome for caregivers. This study intended to explore the experiences of families caring for a child with PKU/HPA in a country with a high PKU rate. The aim of this study was to compare parental well-being between parents of children with and without dietary restrictions and to explore the factors associated with parental psychological well-being. METHODS: Participants were interviewed about their experiences, concerns, and challenges related to the disease by using a semistructured questionnaire. After the interview, parents filled out the Beck Depression Inventory and State-Trait Anxiety Inventory-Trait. RESULTS: This study highlighted the adverse psychological, financial, and social effects of the diagnosis and management of the disease regarding the lives of the families of children with PKU/HPA. Although parental anxiety scores of children with and without dietary restrictions were similar, depressive symptom scores were higher in parents of children with dietary restrictions. However, in multiple regression analysis, lower household income and absence of perceived social support were found to be independent factors associated with higher depressive symptom scores. Having a daughter diagnosed with PKU/HPA and lower household income were found to be factors associated with higher anxiety scores. CONCLUSION: This study revealed that income level, perceived social support, and gender of the child were factors associated with psychological well-being of parents caring for children with PKU/HPA. Health care professionals should identify the challenges faced by families and should be aware of risk factors associated with lower parental well-being to achieve better family adjustment and better health outcomes.

Deoxyguanosine kinase deficiency: a report of four patients.

BACKGROUND: Hepatic involvement is a common feature in childhood mitochondrial disorders. Deoxyguanosine kinase (DGUOK) deficiency is one of the mitochondrial DNA depletion syndromes associated with hepatocerebral syndrome. Hepatic disease and neurologic dysfunction occurs within weeks after birth. Low birth weight is one of the common features. This study aims to describe the clinical and laboratory features of four infants carrying four different pathogenic variants in the DGUOK gene. CASE PRESENTATION: Common clinical findings were progressive cholestatic liver failure, hypoglycemia, hypotonia and rotatory nystagmus in our DGUOK deficiency patients. Lactic acidosis, elevated serum tyrosine and ferritin levels were the striking laboratory features. Cholestasis, iron deposits, microvesicular steatosis and fibrosis were the histopathological findings seen in liver biopsies of two patients. All patients died with multi-organ failure between the ages of 42 days and 6 months. CONCLUSIONS: While neurologic findings may occur later in the course of the disease, elevated serum tyrosine levels may alert the physicians to a DGUOK deficiency in a baby with hepatopathy in the presence of the mentioned signs. Early diagnosis is important not only for genetic counseling but also for a possible liver transplantation.

A Fanconi-Bickel syndrome patient with a novel mutation and accompanying situs inversus totalis.

Tastemel-Öztürk T, Bilginer-Gürbüz B, Teksam Ö, Sivri S. A Fanconi-Bickel syndrome patient with a novel mutation and accompanying situs inversus totalis. Turk J Pediatr 2017; 59: 693-695. Fanconi-Bickel syndrome is a rare autosomal recessive disorder of carbohydrate metabolism, caused by mutations in the SLC2A2 gene, that codes for the glucose transporter protein 2 (GLUT2). The disease is characterized by proximal renal tubular dysfunction, impaired glucose and galactose utilization, and accumulation of glycogen in the liver and kidney. Signs and symptoms of Fanconi-Bickel syndrome begin in infancy and include failure to thrive, hepatomegaly, hypophosphatemic rickets, and short stature. Here in we report a Turkish Fanconi-Bickel syndrome case who also has situs inversus totalis and a novel mutation that has not been described before.

A probable new syndrome with the storage disease phenotype caused by the VPS33A gene mutation.

We present a novel multisystem disease in two siblings with clinical features resembling a lysosomal storage disease. These included coarse face, dysostosis multiplex, respiratory difficulty, proteinuria with glomerular foamy cells, neurological involvement with developmental delays, pyramidal signs, and severe chronic anemia. Detailed enzymatic analysis for lysosomal diseases and whole-exome sequencing studies excluded known lysosomal storage diseases in the proband. Subsequently, genome-wide genotyping and exome sequencing analysis of the family indicated two large homozygous regions on chromosomes 5 and 12, and strongly suggested that a homozygous p. R498W missense mutation in the VPS33A gene might be responsible for this novel disease. Segregation analysis in family members and mutation prediction tools' results also supported the damaging effect of the missense mutation on the function of the Vps33a protein, which plays a role in the vesicular transport system. Electron microscopic studies of the cornea of the proband showed findings supportive of dysfunction in vesicular transport. The clinical phenotype and genetic studies support the suggestion that the siblings most probably have a novel disease very likely caused by a VPS33A gene defect.

Screening for mucopolysaccharidoses in the Turkish population: Analytical and clinical performance of an age-range specific, dye-based, urinary glycosaminoglycan assay.

Comprehensive analytical and diagnostic performance of urinary quantitative GAG analysis with dimethylmethylene blue (DMB) and the age-specific reference ranges were determined in Turkish population, which has a high incidence of MPSs. Precision, linearity, recovery and accuracy/trueness, limits, stability, and effect of interferents were tested according to CLSI guideline. Clinical performance was evaluated with ROC analyses including 45 MPS patients. Intra-day and inter-day precisions were <5% and <11% (CV), respectively. LoD was 9.12mg/L and LoQ was 23.3mg/L. The highest reference values for urinary GAG excretion were determined in an age-specific manner. In the 2-13years age cohort, a cut-off of 89.86mg/g creatinine resulted in 98.07% sensitivity and 93.33% specificity. Proteinuria and hematuria interfered with analysis in some instances. Neither leukocyturia nor pH changes affected the assay. Stability analysis indicated that freezing urine samples for transfer is unnecessary. Of the 45 MPS patient samples evaluated, only three tested negative including MPS II, IVA and VI. Despite limitations due to low levels of urinary GAG excretion in some cases, urinary GAG analysis with DMB with its technical simplicity, low cost, and precise quantitative results, is a valuable screening method, particularly in populations with a high rate of MPSs.

Partial hydatidiform mole in a phenylketonuria patient treated with sapropterin dihydrochloride.

Strict control of hyperphenylalaninemia is necessary in pregnant women with phenylketonuria (PKU) in order to prevent phenylalanine embryopathy in the fetus, characterized by intrauterine growth restriction, dysmorphic facies, congenital heart disease, microcephaly and intellectual disability, collectively known as maternal PKU syndrome. Sapropterin dihydrochloride (SD), an alternative or adjunct to dietary therapy in patients with tetrahydrobiopterin (BH4)-responsive PKU, has recently been used in several cases to treat PKU during pregnancy with satisfactory results. Here, we report two pregnancies treated with SD and unrestricted diet in a patient with BH4-responsive mild PKU. The first pregnancy resulted in a partial hydatidiform mole and was terminated, whereas a healthy infant was born from the second pregnancy. Phenylalanine control was optimal in both pregnancies. To the best of our knowledge, this is the first report on the development of partial hydatidiform mole associated with SD treatment and the second report on molar pregnancy in PKU. While the relation between SD and molar pregnancy is unknown, further studies may be needed to investigate the possible effects of SD on fertilization.

Glutaric aciduria type 2 presenting with acute respiratory failure in an adult.

Glutaric aciduria (GTA) type II can be seen as late onset form with myopathic phenotype. We present a case of a 19-year old female with progressive muscle weakness was admitted in intensive care unit (ICU) with respiratory failure and acute renal failure. Patient was unconscious. Pupils were anisocoric and light reflex was absent. She had hepatomegaly. The laboratory results showed a glucose level of 70 mg/dl and the liver enzymes were high. The patient also had hyponatremia (117 mEq/L) and lactate level of 3.9 mmol/L. Tandem MS and organic acid analysis were compatible with GTA type II. Carnitine 1gr, riboflavin 100 mg and co-enzymeQ10 100 mg was arranged. After four months from beginning of treatment tandem MS results are improved. Respiratory failure, acute renal failure due to profound proximal myopathy can be due to glutaric aciduria type II that responded rapidly to appropriate therapy.

Phenotypic and genotypic spectrum of Turkish patients with isovaleric acidemia.

We aim to investigate the genetic basis of isovaleryl-CoA dehydrogenase (IVD) gene mutations and genotype-phenotype correlations in Turkish patients. Accordingly, bi-directional sequencing was performed to screen 26 patients with isovaleric acidemia (IVA). Nine novels (c.145delC, c.234 + 3G > C, c.506_507insT, p.Glu85Gln, p.Met147Val, p.Ala268Val, p.Ile287Met, p.Gly346Asp and p.Arg382Trp) and six previously reported (c.456 + 2T > C, p.Arg21His, p.Arg21Pro, p.Arg363Cys, p.Arg363His p.Glu379Lys) pathogenic mutations were identified. Pathogenicity of the novel mutations was supported using computational programs. No clear genotype-phenotype correlation could be determined. One of the cases with the novel c.234 + 3G > C mutation has portoseptal liver fibrosis, the clinical condition that was first reported for IVA. This study is the first comprehensive report from Turkey related to IVA genetics that provides information about the high number of disease-causing novel mutations.

Pregnancy and lactation outcomes in a Turkish patient with lysinuric protein intolerance.

Maternal lysinuric protein intolerance (LPI) is associated with increased risk of anemia, toxemia, and retarded growth in fetus during pregnancy, and bleeding complications during delivery. There has been limited number of reports about pregnancy and outcomes of lactation in LPI. Here we present pregnancy and lactation outcomes in a Turkish patient with LPI. In the pregnancy and delivery period, her metabolic status was stable with protein-restricted diet and citrulline. Pathological examination of the placenta revealed multifocal placental infarcts. A successful outcome was achieved with well-controlled anemia, thrombocytopenia despite hemophagocytosis in bone marrow, and placental infarcts during pregnancy. The baby was exclusively breastfed for 6 months. His growth and development was normal. Mild proteinuria started at the fourth month of the delivery. Our case report showed the importance of follow-up of these patients in terms of placental pathologies during pregnancy and for other complications during lactation period.

A case of fucosidosis type II: diagnosed with dysmorphological and radiological findings.

Fucosidosis is a rare autosomal recessive lysosomal storage disorder in which fucose-containing glycolipids, glycoproteins and oligosaccharides accumulate in tissues, as a result of a deficiency of α-L-fucosidase. In this report we describe clinical, dysmorphological and radiological findings of a boy with this disorder. Developmental delay, skeletal deformities and mild coarsening of the face began at two years of age. Clinical signs typical for fucosidosis evolved over time. Psychomotor deterioration progressed slowly. At age 12, he could not walk without help; he was admitted to the hospital with intellectual disability, short stature and coarse facial features. A skeletal survey showed dysostosis multiplex. Cranial MRI demonstrated high intensities on the periventricular white matter and low intensities on the basal ganglia on T2-weighted images. Despite the absence of angiokeratoma on the skin, type II fucosidosis with clinical, dysmorphological and radiological signs was suspected. The diagnosis was established on the basis of severely decreased activity of α-L-fucosidase in the leukocytes. The natural history and specific dysmorphic and radiological findings should, even in the absence of angiokeratoma, assist in the differential diagnosis of this rare condition when lysosomal storage disorders are suspected, particularly in populations in which consanguineous marriages are common.