Early diagnostic clues of mucolipidosis type II: Significance of radiological findings.

Mucolipidosis type-II (ML-II) is an ultra-rare disorder caused by deficiency of N-acetylglucosaminyl-1-phosphotransferase enzyme due to biallelic pathogenic variants in GNPTAB gene. There are a few known about the natural history of ML-II. In this study, we presented the natural course of 24 patients diagnosed with ML-II. Mean age at diagnosis was 9.3 ± 5.7 months. All patients had coarse face, developmental delay, and hypotonia. The mean survival time was 3.01 ± 1.4 years. The oldest patient was 6.5 years old. Twelve patients died due to lung infection and respiratory failure. We observed early and significant radiological findings of ML-II were different from typical dysostosis multiplex such as femoral cloaking, rickets-like changes, and talocalcaneal stippling. These are significant findings observed in the fetal or newborn period which is considered to be highly characteristic of ML-II and disappears in the first year. Cloaking, rickets-like changes, and stippling were not observed in patients older than three months of age and this suggests that these findings disappear within the first year. These radiological features can be used as important clues for diagnosis. We detected eight different pathogenic variants in GNPTAB gene, three of them were novel.

Actions speak louder than words: Home visits and its effect on dietary adherence in patients with phenylketonuria.

AIM: Phenylketonuria (PKU) is an inherited metabolic disorder in which accumulation of phenylalanine (Phe) leads to poor neurological outcomes without treatment. Dietary therapy is the main treatment and nonadherence is associated with elevated blood Phe levels and correspondingly poor neuropsychiatric outcomes. This study aimed to examine the effect of home visits on blood Phe levels in PKU patients. METHODS: Sixty-five paediatric PKU patients who were on low-phenylalanine diet were visited monthly at home for 6 months. At each visit, dietary education was provided, patients' height and weight were measured and blood samples were collected. RESULTS: Twenty-eight (43.1%) patients had classic PKU and 37 (56.9%) had moderate PKU. Blood Phe levels decreased statistically significant at first, second, fifth, and sixth months compared with screening visit. Blood Phe levels in moderate PKU patients decreased significantly at the last visit unlike classic PKU patients. A significant decrease in blood Phe levels was observed in patients older than 10 years. Anthropometric parameters improved. CONCLUSIONS: Dietary nonadherence is the main treatment failure in PKU. Home visits for education are a promising way to improve treatment outcomes by providing quality education, better assessment, and correction of mistakes but they should be ongoing and supported by different interventions that address patients' special needs.

Perspectives of adult patients with lysosomal storage diseases on the transition from pediatric to adult healthcare in Turkey.

AIM: In many countries, adult clinics specifically dedicated to adult patients with lysosomal storage diseases (LSDs) do not exist. In Turkey, these patients are managed either by pediatric metabolic specialists or adult physicians who do not specifically specialize in LSDs. In this study, we aimed to identify the unmet clinical needs of these adult patients and their suggestions. METHODS: The focus group participants were 24 adult LSD patients. Interviews were conducted in person. RESULTS: A total of 23 LSD patients and parents of a patient with mucopolysaccharidosis type-3b with intellectual deficit were interviewed, with 84.6% of patients diagnosed after the age of 18 years and 18% of patients diagnosed before the age of 18 years desiring management by adult physicians. Patients with particular physical characteristics or severe intellectual deficit declined the transition. Patients reported structural problems in the hospital and social problems associated with pediatric clinics. They made suggestions to facilitate the possible transition. CONCLUSION: With improved care, more patients with LSDs survive into adulthood or receive the diagnosis in adulthood. Children with chronic diseases need to transition to the care of adult physicians when they reach adulthood. Thus, there is an increasing need for adult physicians to manage these patients. In this study, most LSD patients accepted a well-planned and organized transition. Problems were related to stigmatization and social isolation in the pediatric clinic or adult issues with which pediatricians are not familiar. There is a need for adult metabolic physicians. Thus, health authorities should adopt necessary regulations for training of physicians in this field.

Expanding the phenotypic landscape of Gaucher disease type 3c with a novel entity - Transient neonatal cholestasis.

Gaucher disease (GD) is the most frequent lysosomal storage disorder due to biallelic pathogenic variants in GBA gene. Only homozygous D409H variant has been associated with the cardiovascular phenotype which is also known as Gaucher disease type 3c. In this descriptive study, we presented phenotypic heterogeneity and a novel clinical finding among 13 patients with GD type 3c. Patients presented with varying degrees of cardiac valve and/or aortic calcifications (84,6%) and corneal opacities (76,9%) in addition to visceral (100%), hematological (92,3%), neurological (92,3%), and skeletal (30%) manifestations. Also, cervical dystonia (38,4%) and psychiatric disorders (46,1%) were not infrequent entities with respect to neurological involvement in GD type 3c. In this report, we highlight transient neonatal cholestasis (38,4%) as a novel finding in GD type 3c. Neonatal cholestasis is a finding associated with Gaucher type 2, but transient neonatal cholestasis has not been reported in GD patients, so far. The clinical features of GD type 3c are highly heterogeneous, from disease severity or age of onset to disease progression. Also, we concluded that phenotypic spectrum may be associated with age at onset of clinical symptoms. As, patients presenting in infancy or childhood had mainly visceral and hematological involvement and patients presenting in adolescence and adulthood had mainly cardiac, neurological involvement, and psychiatric behavioral disorders. Identifying the heterogeneous clinical course of these patients in this fatal disease, may lead a sufficient understanding of the pathophysiology which will enable targeted therapeutic interventions.

Three-Country Snapshot of Ornithine Transcarbamylase Deficiency.

X-linked ornithine transcarbamylase deficiency (OTCD) is the most common urea cycle defect. The disease severity ranges from asymptomatic carrier state to severe neonatal presentation with hyperammonaemic encephalopathy. We audited the diagnosis and management of OTCD, using an online 12-question-survey that was sent to 75 metabolic centres in Turkey, France and the UK. Thirty-nine centres responded and 495 patients were reported in total. A total of 208 French patients were reported, including 71 (34%) males, 86 (41%) symptomatic and 51 (25%) asymptomatic females. Eighty-five Turkish patients included 32 (38%) males, 39 (46%) symptomatic and 14 (16%) asymptomatic females. Out of the 202 UK patients, 66 (33%) were male, 83 (41%) asymptomatic and 53 (26%) symptomatic females. A total of 19%, 12% and 7% of the patients presented with a neonatal-onset phenotype in France, Turkey and the UK, respectively. Vomiting, altered mental status and encephalopathy were the most common initial symptoms in all three countries. While 69% in France and 79% in Turkey were receiving protein restriction, 42% were on a protein-restricted diet in the UK. A total of 76%, 47% and 33% of patients were treated with ammonia scavengers in Turkey, France and the UK, respectively. The findings of our audit emphasize the differences and similarities in manifestations and management practices in three countries.

Pyridoxine-dependent Epilepsy caused by a Novel homozygous mutation in PLPBP Gene.

Seizures in newborn infants may be the first finding of hereditary metabolic diseases. Pyridoxine-dependent epilepsy (PDE) is a treatable disorder associated with defects in the one of ALDH7A1, PNPO, or PLPBP genes and it is uncommon but progresses with persistent seizures in the neonatal and infancy period. The seizures are generally resistant to traditional antiepileptic drugs and show a dramatic response to high-dose pyridoxine. In 2016, mutations were reported in PLPBP (previously known as PROSC) gene, which encodes pyridoxal phosphate homeostatic protein (PLPHP).When early-onset antiepileptic resistant seizures are not treated, clinical findings emerge including the development of encephalopathy, congenital microcephaly, and subsequent retardation of psychomotor development. The present case is a 33-month-old female infant with seizures starting from postnatal day 1, who did not respond to traditional anti-epileptic drugs but responded to pyridoxine treatment. In the genetic tests, homozygote c.695 C > T (p.Ala232Val) mutation was determined in the PLPBP gene, which has not been previously identified. Since a specific treatment was found, this case is reported with the aim of emphasizing the need to consider pyridoxine dependence, which is one of the vitamin-dependent metabolic encephalopathies, in the differential diagnosis of epilepsy patients.

Evaluation of bone health in patients with mucopolysaccharidosis.

INTRODUCTION: This study aimed to evaluate the relationship between clinical findings, height and weight standard deviation scores, 25-hydroxyvitamin D3 (25(OH)D3) level, and dual-energy X-ray absorptiometry (DXA) results in patients diagnosed with mucopolysaccharidosis (MPS), where effective current treatments such as enzyme replacement therapy (ERT) can be accessed. MATERIALS AND METHODS: 25(OH)D3 level was measured in 126 patients with MPS (17 with MPS I, 14 with MPS II, 18 with MPS III, 33 with MPS IVA, and 44 with MPS VI; 24-524 months). DXA was performed in 45 of these patients (8 with MPS I, 4 with MPS II, 4 with MPS III, 12 with MPS IVA, and 17 with MPS VI; 62-197 months; all patients were under 18 when DXA was performed) to assess bone mineral density (BMD) of the lumbar spine. RESULTS: In total, 67.5% patients had a short stature, and 50% of them were underweight for their age. Of the patients, 13.5% were immobile, 28.6% had 25(OH)D3 deficiency, and 30.2% had an insufficient level of 25(OH)D3. BMD z score of 45 patients was - 2.5 ± 1.7. In 40% patients, it was < - 2. However, after correction for height-for-age z score (HAZ), HAZ-adjusted BMD z score was - 0.1 ± 0.9. In 2.2% patients, it was < - 2. CONCLUSION: The low BMD z score prevalence reported with DXA was misleadingly higher in children with MPS and short stature. To prevent exposure to unnecessary antiresorptive treatments in these children, the effect of severe short stature and bone geometry on DXA measurements should be considered; further studies on bone health are warranted.

More than tubular dysfunction: cystinosis and kidney outcomes.

BACKGROUND: Cystinosis is a lysosomal storage disease that affects many tissues. Its prognosis depends predominantly on kidney involvement. Cystinosis has three clinical forms: nephropathic infantile, nephropathic juvenile and non-nephropathic adult. Proximal tubular dysfunction is prominent in the infantile form, whereas a combination of glomerular and tubular alterations are observed in the juvenile form. METHODS: Thirty-six children with nephropathic cystinosis were included in the study. Clinical features, molecular genetic diagnoses, and kidney outcomes of the patients were evaluated. RESULTS: Twenty-one children (58.3%) were male. The median age at diagnosis was 18.5 months. Twenty-eight patients (77.8%) had infantile nephropathic cystinosis, while eight (22.2%) had juvenile nephropathic cystinosis. An acute rapid deterioration of the kidney function with proteinuria, hypoalbuminemia, and nephrotic syndrome, was observed in 37.5% of patients with the juvenile form. The mean estimated glomerular filtration rate (eGFR) was 82.31 ± 37.45 ml/min/1.73m2 at diagnosis and 63.10 ± 54.60 ml/min/1.73m2 at the last visit (p = 0.01). Six patients (16.6%) had kidney replacement therapy (KRT) at the last visit. The median age of patients with kidney failure was 122 months. Patients with a spot urine protein/creatinine ratio < 6 mg/mg at the time of diagnosis had better kidney outcomes (p = 0.01). The most common allele was c.451A>G (32.6%). The patients with the most common mutation tended to have higher mean eGFR and lower leukocyte cystine levels than patients with other mutations. CONCLUSION: Glomerulonephritis may be a frequent finding in addition to the well-known tubular dysfunction in patients with cystinosis. Furthermore, our results highlight that the presence of severe proteinuria at the time of diagnosis is a relevant prognostic factor for kidney survival.

Molecular Diagnosis of Monogenic Diabetes and Their Clinical/Laboratory Features in Turkish Children

Objective: Monogenic diabetes is a heterogeneous disease that causes functional problems in pancreatic beta cells and hyperglycemia. The aim of this study was to determine the clinical and laboratory features, the admission characteristics and distribution of monogenic form of diabetes in childhood in Turkey. Methods: Patients aged 0-18 years, who were molecularly diagnosed with monogenic diabetes, and consented to participate, were included in the study. Results: Seventy-seven (45.6%) female and 92 male cases with a mean age of 8.18±5.05 years at diagnosis were included. 52.7% of the cases were diagnosed with monogenic diabetes by random blood glucose measurement. The reason for genetic analysis in 95 (56.2%) of cases was having a family member diagnosed with diabetes under the age of 25. At the time of diagnosis, ketone was detected in urine in 16.6% of the cases. Mean hemoglobin A1c on admission, fasting blood glucose, fasting insulin, and c-peptide values were 7.3±2.1%, 184.9±128.9 mg/dL, 9.4±22.9 IU/L, 1.36±1.1 and ng/L respectively. GCK-MODY was found in 100 (59.2%), HNF1A-MODY in 31 (18.3%), and variants in ABCC8 in 6 (3.6%), KCNJ11 in 5 (3%), HNF4A in 2 (1.2%), and HNF1B in 2 (1.2%). Conclusion: Recent studies have indicated HNF1A-MODY is the most frequent of all the MODY-monogenic diabetes cases in the literature (50%), while GCK-MODY is the second most frequent (32%). In contrast to these reports, in our study, the most common form was GCK-MODY while less than 20% of cases were diagnosed with HNF1A-MODY.

Glycogen storage disease type XII; an ultra rare cause of hemolytic anemia and rhabdomyolysis: one new case report.

OBJECTIVES: Aldolase A deficiency also known as glycogen storage disease (GSD) XII, is an ultra rare autosomal recessively inherited GSD, associated with hemolytic anemia and rhabdomyolysis. CASE PRESENTATION: Here, we first report a patient with dermatological findings, hemodialysis requirement for rhabdomyolysis, and a novel likely pathogenic c.971C>T (p.A324V) mutation in the ALDOA gene. CONCLUSIONS: Episodes of rhabdomyolysis can be triggered by febrile illnesses and catabolic processes. Diagnosis should be confirmed by the mutation analysis of ALDOA gene. Treatment includes management of hemolytic anemia and administration of antipyretics during febrile episodes to avoid hemolysis and rhabdomyolysis.

Morquio A syndrome and effect of enzyme replacement therapy in different age groups of Turkish patients: a case series.

BACKGROUND: This case series includes longitudinal clinical data of ten patients with Morquio A syndrome from south and southeastern parts of Turkey, which were retrospectively collected from medical records. All patients received enzyme replacement therapy (ERT). Clinical data collected included physical appearance, anthropometric data, neurological and psychological examinations, cardiovascular evaluation, pulmonary function tests, eye and ear-nose-throat examinations, endurance in the 6-min walk test and/or 3-min stair climb test, joint range of motion, and skeletal investigations (X-rays, bone mineral density). RESULTS: At the time of ERT initiation, two patients were infants (1.8 and 2.1 years), five were children (3.4-7.1 years), and three were adults (16.5-39.5 years). Patients had up to 4 years follow-up. Most patients had classical Morquio A, based on genotypic and phenotypic data. Endurance was considerably reduced in all patients, but remained relatively stable or increased over time in most cases after treatment initiation. Length/height fell below normal growth curves, except in the two infants who started ERT at ≤ 2.1 years of age. All patients had skeletal and/or joint abnormalities when ERT was started. Follow-up data did not suggest improvements in skeletal abnormalities, except in one of the younger infants. Nine patients had corneal clouding, which resolved after treatment initiation in the two infants, but not in the other patients. Hepatomegaly was reported in seven patients and resolved with treatment in five of them. Other frequent findings at treatment initiation were coarse facial features (N = 9), hearing loss (N = 6), and cardiac abnormalities (N = 6). Cardiac disease deteriorated over time in three patients, but did not progress in the others. CONCLUSIONS: Overall, this case series with Morquio A patients confirms clinical trial data showing long-term stabilization of endurance after treatment initiation across ages and suggest that very early initiation of ERT optimizes growth outcomes.

The outcome of 41 Late-Diagnosed Turkish GA-1 Patients: A Candidate for the Turkish NBS.

BACKGROUND: Glutaric aciduria type 1(GA-1) is an inherited cerebral organic aciduria. Untreated patients with GA-1 have a risk of acute encephalopathic crises during the first 6 years of life. In so far as GA-1 desperately does not exist in Turkish newborn screening (NBS) program, most patients in our study were late-diagnosed. METHOD: This study included 41 patients diagnosed with acylcarnitine profile, urinary organic acids, mutation analyses in the symptomatic period. We presented with clinical, neuroradiological, and molecular data of our 41 patients. RESULTS: The mean age at diagnosis was 14.8 ± 13.9 (15 days to 72 months) and, high blood glutaconic acid, glutarylcarnitine and urinary glutaric acid (GA) levels in 41 patients were revealed. Seventeen different mutations in the glutaryl-CoA dehydrogenase gene were identified, five of which were novel. The patients, most of whom were late-diagnosed, had a poor neurological outcome. Treatment strategies made a little improvement in dystonia and the frequency of encephalopathic attacks. CONCLUSION: All GA-1 patients in our study were severely affected since they were late-diagnosed, while others show that GA-1 is a treatable metabolic disorder if it is diagnosed with NBS. This study provides an essential perspective of the severe impact on GA-1 patients unless it is diagnosed with NBS. We immediately advocate GA-1 to be included in the Turkish NBS.

Clinical and molecular findings in 37 Turkish patients with isolated methylmalonic acidemia

Background/aim: Isolated methylmalonic acidemia (MMA) is caused by complete or partial deficiency of the enzyme methylmalonyl- CoA mutase (mut0 or mut­ enzymatic subtype), a defect of its cofactor adenosyl-cobalamin (cblA, cblB, or cblD-MMA), or deficiency of the enzyme methylmalonyl-CoA epimerase. While onset of the disease ranges from the neonatal period to adulthood, most cases present with lethargy, vomiting and ketoacidosis in the early infancy. Major secondary complications are; growth failure, developmental delay, interstitial nephritis with progressive renal failure, basal ganglia injury and cardiomyopathy. We aimed to demonstrate clinical and molecular findings based on long-term follow up in our patient cohort. Materials and methods: The study includes 37 Turkish patients with isolated MMA who were followed up for long term complications 1 to 14 years. All patients were followed up regularly with clinical, biochemical and dietary monitoring to determine long term complications. Next Generation Sequencing technique was used for mutation screening in five disease-causing genes including; MUT, MMAA, MMAB, MMADHC, MCEE genes. Mutation screening identified 30 different types of mutations. Results: While 28 of these mutations were previously reported, one novel MMAA mutation p.H382Pfs*24 (c.1145delA) and one novel MUT mutation IVS3+1G>T(c.752+1G>T) has been reported. The most common clinical complications were growth retardation, renal involvement, mental motor retardation and developmental delay. Furthermore, one of our patients developed cardiomyopathy, another one died because of hepatic failure and one presented with lactic acidosis after linezolid exposure. Conclusion: We have detected two novel mutations, including one splice-site mutation in the MUT gene and one frame shift mutation in the MMAA gene in 37 Turkish patients. We confirm the genotype-phenotype correlation in the study population according to the long-term complications.

Clinical features of 27 Turkish Propionic acidemia patients with 12 novel mutations.

Kör D, Seker-Yilmaz B, Bulut FD, Kilavuz S, Öktem M, Ceylaner S, Yildizdas D, Önenli-Mungan N. Clinical features of 27 Turkish Propionic acidemia patients with 12 novel mutations. Turk J Pediatr 2019; 61: 330-336. Propionic acidemia (PA) is an inherited metabolic disease caused by the deficiency of one of the four biotin-dependent enzymes propionyl-CoA carboxylase (PCC), and is characterized by coma and death in unrecognized patients, additionally late diagnosis leads to severe developmental delay and neurological sequels. Manifestations of PA over time can include growth impairment, intellectual disability, seizures, basal ganglia lesions, pancreatitis, and cardiomyopathy. Other rarely reported complications include optic atrophy, hearing loss, premature ovarian insufficiency, and chronic renal failure. Mutations in PCCA-PCCB genes cause the clinically heterogeneous disease of PA. In this study, we investigate the mutation spectrum of PCCAPCCB genes and phenotypic features of 27 Turkish patients with PA from the South and Southeast parts of Turkey. We report 12 novel PA mutations, five affecting the PCCA gene and 7 affecting the PCCB gene.

Current status of the congenital hypothyroidism neonatal screening program in Adana Province, Turkey.

BACKGROUND: Congenital hypothyroidism (CH) is a common cause of mental retardation; it has a worldwide incidence ranging from 1:3000 to 1:4500 live births. Predictably, an increase in the reported incidence of primary CH occurs when the cut-off levels of thyroid-stimulating hormone are lowered. We aimed to evaluate the results of a congenital hypothyroidism screening program and current status in this study. METHODS: Analysis results of 1300 infants who were referred to the endocrinology polyclinic because of suspected CH within the scope of the Ministry of Health National Neonatal Screening Program were retrospectively evaluated. RESULTS: The diagnosis of CH and initiation of treatment were both done in 223 (18.5%) and 10 (0.8%) infants as a result of the initial evaluation and follow-up, respectively. The mean capillary and venous thyroid-stimulating hormone (TSH) levels of 223 patients were 40.78 (5.5-100) µIU/mL and 67.26 (10.7-100) µIU/mL, respectively. These patients' mean heel prick time was 8.65 (0-30, median: 7) days. The mean age of the 223 infants whose treatment was initiated as a result of the initial evaluation was 19.87 (4-51, median: 20) days, and the mean age of the infants whose treatment was started at follow-up was 43.71 (29-65) days. The duration between heel prick time and venous TSH time was 11.10 (2-28, median: 11) days and was longer than planned (3-5 days). CONCLUSIONS: Although the duration for the diagnosis and initiation of CH treatment were markedly reduced with the implementation of the screening program in Turkey compared to those before the implementation of the screening program, we have not yet achieved the ideal time (≤14 days).

Four Gaucher disease type II patients with three novel mutations: a single centre experience from Turkey.

Gaucher disease is the most common lysosomal storage disorder due to glucosylceramidase enzyme deficiency. There are three subtypes of the disease. Neurological involvement accompanies visceral and haematological findings only in type II and type III Gaucher patients. Type II is the acute progressive neuronopathic form which is the most severe and rare subtype. Clinical findings are recognized prenatally or in the first months of life and followed by death within the first two years of age. Among our 81 Gaucher patients, we identified 4 (4,9%) type II patients in our metabolic centre. This rate is significantly higher than the rate reported in the literature (<1%). Three of the patients had novel mutations, one of them was a collodion baby and the other one was mistyped as type III due to its atypical presentation at the beginning and he was treated with ERT for 8 months. In this report, we present our type II Gaucher patients with three novel mutations and one perinatal lethal form with generalized ichthyosis which is a very rare disorder. Additionally, we would like to highlight the phenotypic heterogeneity not only between the subtypes, also even in the same type.

Twenty-seven mutations with three novel pathologenic variants causing biotinidase deficiency: a report of 203 patients from the southeastern part of Turkey.

BACKGROUND: Biotinidase deficiency (BD) is an autosomal recessive inborn error of metabolism characterized by neurologic and cutaneous symptoms and can be detected by newborn screening. Newborn screening for BD was implemented in Turkey at the end of 2008. METHODS: In total, 203 patients who were identified among the infants detected by the newborn screening were later confirmed to have BD through measurement of serum biotinidase activity. We also performed BTD mutation analysis to characterize the genetic profile. RESULTS: Twenty-seven mutations were identified. The most commonly found variants were c.1330G>C (p.D444H), c.1595C>T (p.T532M), c.470G>A (p.R157H), and c.198_104delGCGGCTGinsTCC (p.C33Ffs ) with allele frequencies of 0.387, 0.175, 0.165 and 0.049, respectively. Three novel pathogenic and likely pathogenic variants were identified: p.W140* (c.419G>A), p.S319F (c.956C>T) and p.L69Hfs*24 (c.192_193insCATC). We also identified three mutations reported in just one patient in the past (p.V442Sfs*59 [c.1324delG], p.H447R [c.1340A>G] and p.198delV [c.592_594delGTC]). Although all of the patients were asymptomatic under the treatment of biotin, only one patient, who had the novel c.419G>A homozygous mutation became symptomatic during an episode of acute gastroenteritis with a presentation of ketosis and metabolic acidosis. Among the screened patients, 156 had partial and 47 had profound BD. CONCLUSIONS: We determined the mutation spectra of BD from the southeastern part of Turkey. The results of this study add three more mutations to the total number of mutations described as causing BD.

Turkish case of ethylmalonic encephalopathy misdiagnosed as short chain acyl-CoA dehydrogenase deficiency.

Ethylmalonic encephalopathy is a very rare autosomal recessively inherited inborn error of metabolism; characterized by encephalopathy, recurrent petechiae without bleeding diathesis, chronic diarrhea, and orthostatic acrocyanosis. Here, we describe a case of ethylmalonic encephalopathy with late onset neurologic symptoms and a confusing family history of two deceased brothers with the wrong suspicion of short chain acyl-CoA dehydrogenase deficiency.

Improved metabolic control in tetrahydrobiopterin (BH4), responsive phenylketonuria with sapropterin administered in two divided doses vs. a single daily dose.

BACKGROUND: Phenylketonuria (PKU) often requires a lifelong phenylalanine (Phe)-restricted diet. Introduction of 6R-tetrahydrobiopterin (BH4) has made a huge difference in the diets of patients with PKU. BH4 is the co-factor of the enzyme phenylalanine hydroxylase (PAH) and improves PAH activity and, thus, Phe tolerance in the diet. A limited number of published studies suggest a pharmacodynamic profile of BH4 more suitable to be administered in divided daily doses. METHODS: After a 72-h BH4 loading test, sapropterin was initiated in 50 responsive patients. This case-control study was conducted by administering the same daily dose of sapropterin in group 1 (n=24) as a customary single dose or in two divided doses in group 2 (n=26) over 1 year. RESULTS: Mean daily consumption of Phe increased significantly after the first year of BH4 treatment in group 2 compared to group 1 (p<0.05). At the end of the first year of treatment with BH4, another dramatic difference observed between the two groups was the ability to transition to a Phe-free diet. Eight patients from group 2 and two from group 1 could quit dietary restriction. CONCLUSIONS: When given in two divided daily doses, BH4 was more efficacious than a single daily dose in increasing daily Phe consumption, Phe tolerance and the ability to transition to a Phe-unrestricted diet at the end of the first year of treatment.

Impaired glucose tolerance in Fanconi-Bickel syndrome: Eight patients with two novel mutations.

Seker-Yilmaz B, Kör D, Bulut FD, Yüksel B, Karabay-Bayazit A, Topaloglu AK, Ceylaner G, Önenli-Mungan N. Impaired glucose tolerance in Fanconi-Bickel syndrome: Eight patients with two novel mutations. Turk J Pediatr 2017; 59: 434-441. Fanconi-Bickel syndrome (FBS) is a rare, autosomal recessive disorder of carbohydrate metabolism caused by defects in the facilitative glucose transporter 2 (GLUT2 or SLC2A2) gene. Prominent findings are failure to thrive, renal tubular acidosis, hypoglycemia and postprandial hyperglycemia even mimicking diabetes mellitus. Eight patients from 6 families with FBS were included in this study. c.482_483insC homozygous mutation was detected in six patients from four different families. Mutation analysis of SLC2A2 gene revealed two novel homozygous mutations; c.1069delGinsAATAA and c.575A > G. Standard oral glucose tolerance test with 1.75 g/kg oral glucose was performed in six of the patients who were older than 3-years of age. Impaired glucose tolerance was found in all patients as expected and two of them had overt diabetes. None of the antidiabetic medications were given to them in order to avoid significant hypoglycemia. Beside the conservative treatment, follow up with frequent oral glucose tolerance tests are planned. We report these cases of FBS, as GSD XI is rare, two novel mutations were detected and also to highlight the risk of diabetes mellitus; although there is not a consensus about the treatment.