Electro-clinical features and long-term outcomes in guanidinoacetate methyltransferase (GAMT) deficiency

OBJECTIVE

To evaluate clinical characteristics and long-term outcomes in patients with guanidinoacetate methyltransferase (GAMT) deficiency with a special emphasis on seizures and electroencephalography (EEG) findings.

METHODS

We retrospectively analyzed the clinical and molecular characteristics, seizure types, EEG findings, neuroimaging features, clinical severity scores, and treatment outcomes in six patients diagnosed with GAMT deficiency.

RESULTS

Median age at presentation and diagnosis were 11.5 months (8-12 months) and 63 months (18 months -11 years), respectively. Median duration of follow-up was 14 years. Global developmental delay (6/6) and seizures (5/6) were the most common symptoms. Four patients presented with febrile seizures. The age at seizure-onset ranged between 8 months and 4 years. Most common seizure types were generalized tonic seizures (n = 4) and motor seizures resulting in drop attacks (n = 3). Slow background activity (n = 5) and generalized irregular sharp and slow waves (n = 3) were the most common EEG findings. Burst-suppression and electrical status epilepticus during slow-wave sleep (ESES) pattern was present in one patient. Three of six patients had drug-resistant epilepsy. Post-treatment clinical severity scores showed improvement regarding movement disorders and epilepsy. All patients were seizure-free in the follow-up.

CONCLUSIONS

Epilepsy is one of the main symptoms in GAMT deficiency with various seizure types and non-specific EEG findings. Early diagnosis and initiation of treatment are crucial for better seizure and cognitive outcomes. This long-term follow up study highlights to include cerebral creatine deficiency syndromes in the differential diagnosis of patients with global developmental delay and epilepsy and describes the course under treatment.

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.

Single Institutional Experience with GM1 Gangliosidosis: Clinical and Laboratory Results of 14 Patients

Background:

GM1 gangliosidosis is an autosomal recessive lysosomal storage disease caused by biallelic mutations in the GLB1 gene. Neurodegeneration, hypotonia, visceromegaly, macular cherry-red spots, skeletal dysplasia, and coarse and dysmorphic face are the major clinical features.

Aims:

To evaluate the demographic and clinical data of patients with GM1 gangliosidosis in a single center.

Study Design:

A retrospective clinical study.

Methods:

This study included patients followed at Hacettepe University İhsan Doğramacı Children’s Hospital Pediatric Metabolism Unit with the diagnosis of GM1 gangliosidosis between 1988 and 2021. Hospital records of the patients were reviewed for demographic, clinical, and laboratory findings.

Results:

Fourteen patients were included in the study and 10 (71.4%) were male. The age at onset of clinical symptoms was between 0 and 5 months, and the median time to diagnosis after the first symptom was 4.3 (0-13) months. Motor delay (54%) was the most common initial symptom. The median follow-up period was 14.8 (0.4-92.2) months. Twelve patients (85.7%) died, and all deaths occurred before the age of 24 months. The median survival was 21.3 (95% confidence interval, 15.5-24.9) months. Higher leukocyte beta-galactosidase activity correlated with later age at onset (ρ = 0.575), later age at diagnosis (ρ = 0.618), and longer diagnostic delay (ρ = 0.702) (ρ < 0.05).

Conclusion:

Median survival in patients with GM1 gangliosidosis is less than 24 months. Beta-galactosidase enzyme activity may be associated with clinical onset and time of diagnosis in these patients.

Recommendations on phenylketonuria in Turkey

BACKGROUND

Phenylketonuria (PKU), is an autosomal recessive disease leading to the conversion defect of phenylalanine (Phe) into tyrosine. Severe neurocognitive and behavioral outcomes are observed in untreated cases. The present paper aims to review clinical experiences and expert recommendations in diagnosis, treatment, and follow-up of pediatric PKU patients in Turkey.

METHODS

Two advisory board meetings were held in the year 2016 and 2017 with contributions of four leading experts in this field, and an online update meeting was held for final decisions about statements, and conclusions in January 2021. Considering management gaps in diagnosis, treatment, and follow-up of PKU, discussion points are defined. The Committee members then reviewed the Turkish and general literature and the final statements were formulated.

RESULTS

The diagnostic cut-off for dried blood spots should remain at 2 mg/dl. Treatment cut-off value is acceptable at 6 mg/dl. Compliance with an ideal follow-up list is strongly recommended. Total protein intake should not be limited. Age-related safe levels of protein intake should be encouraged with an additional 40% from L-amino acids supplements, a 20% compensatory factor to account for the digestibility and utilization of amino acids from the supplement, and a further 20% compensation to optimize Phe control. Cognitive impairment and intelligence quotient evaluations should be performed at least twice before 3 years of age. In pregnant women, the target Phe level should be < 5 mg/dl, and they should be followed-up weekly in the first trimester, then every 2 weeks after organogenesis. Novel pharmacological treatments are promising, but some of them have limitations for our country.

CONCLUSIONS

Early diagnosis and treatment initiation; determination and standardization of diagnostic and treatment thresholds; treatment modalities and follow-up parameters are significant steps in treating PKU in the long term. PKU follow-up is a dynamic process with uncertainties and differences in clinical practice.

COVID-19-related anxiety in phenylketonuria patients

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.

Autism spectrum disorder in patients with inherited metabolic disorders-a large sample from a tertiary center

BACKGROUND

There is increased awareness regarding the co-occurrence of autism spectrum disorder (ASD) and inherited metabolic disorders (IMD), and this is crucial for the management of both diagnoses in clinical practice. We aimed firstly to report twenty-two patients with a dual diagnosis of IMD and ASD who are still being followed up in the child metabolism outpatient clinic; secondly to evaluate the time of both IMD and ASD diagnosis and the clinical progress of their metabolic disorders to underline treatable conditions.

METHODS

Among the patients admitted to the Pediatric Metabolism outpatient clinic because of IMD, twentytwo of them who had a diagnosis of ASD were included in the study. Data of the patients were collected from their medical records. The most recent progress of the patients concerning their metabolic disorder was obtained from the patients` files.

RESULTS

Six cases with Phenylketonuria, 2 cases with partial Biotinidase Deficiency, 3 cases with Cerebral Creatine Deficiency Syndrome (CCDS), 5 cases with Mucopolysaccharidosis (MPS) Type-3b, 2 cases with MPS Type-3a, 1 case with MPS Type 4, 2 cases with Hypervalinemia and 1 case with Maple Syrup Urine Disease were all diagnosed as also having ASD. The diagnoses of CCDS and MPS Type 3 were after the diagnosis of ASD. Phenylketonuria and Mucopolysaccharidosis were the most common diagnoses in our study. In addition, rare entities such as MPS Type 3b and Type 4 and Hypervalinemia were also reported to co-occur with autism.

CONCLUSIONS

Considering the co-occurrence of both disorders and implementing intervention strategies accordingly will certainly be beneficial in clinical practice and particularly in countries with a high rate of consanguinity.

Clinical and molecular characteristics of carnitineacylcarnitine translocase deficiency with c.270delC and a novel c.408C>A variant

BACKGROUND

Carnitine-acylcarnitine translocase deficiency (CACTD) is a rare, autosomal recessive, and highly lethal fatty acid oxidation (FAO) disorder caused by defective acylcarnitine transport across the mitochondrial membrane. CACTD is characterized by severe episodes of hypoglycemia and hyperammonemia, seizures, cardiomyopathy, liver dysfunction, severe neurological damage, and muscle weakness. Herein, we described the clinical features, biochemical, and molecular findings of three patients with CACTD, presented with poor feeding, hypoglycemia, liver dysfunctions, and hyperammonemia, but died despite intensive treatment.

CASES

All cases had similar signs and symptoms like poor feeding and respiratory failure associated with liver dysfunction. Urinary organic acid profiles in the presence of hypoglycemia and hyperammonemia led us to the possible diagnosis of one of fatty acid β-oxidation defects. Results of the molecular analyses were compatible with CACTD. In addition to known mutation (c.270delC;p.Phe91Leufs*38) we detected a novel one (c.408C > A;p.Cys136*).

CONCLUSIONS

All three cases died despite a very intensive therapy. Based on our experience with these three cases, it can be said that CACTD has a relatively poor prognosis, molecular studies are of most importance in suspected cases for the final diagnosis and such studies might be of help while giving genetic counselling and guidance to parents for future pregnancies.

A new UHPLC-MS/MS method for the screening of urinary oligosaccharides expands the detection of storage disorders

Background

Oligosaccharidoses are storage disorders due to enzymatic defects involved in the breakdown of the oligosaccharidic component of glycosylated proteins. The defect cause the accumulation of oligosaccharides (OS) and, depending on the lacking enzyme, results in characteristic profiles which are helpful for the diagnosis. We developed a new tandem mass spectrometry method for the screening of urinary OS which was applied to identify a large panel of storage disorders.

Methods

The method was set-up in urine and dried urine spots (DUS). Samples were analysed, without derivatization and using maltoheptaose as internal standard, by UHPLC-MS/MS with MRM acquisition of target OS transitions, including Glc4, the biomarker of Pompe disease. The chromatographic run was < 30 min. Samples from patients with known storage disorders were used for clinical validation.

Results

The method allowed to confirm the diagnosis of oligosaccharidoses (sialidosis, α-/β-mannosidosis, fucosidosis, aspartylglucosaminuria) and of GM1 and GM2 (Sandhoff type) gangliosidosis, by detecting specific OS profiles. In other storage disorders (mucolipidosis II and III, mucopolysaccharidosis type IVB) the analyisis revealed abnormal OS excretion with non-specific profiles. Besides Pompe disease, the tetrasaccharide Glc4 was increased also in disorders of autophagy (Vici syndrome, Yunis-Varon syndrome, and Danon disease) presenting cardiomuscular involvement with glycogen storage. Overall, results showed a clear separation between patients and controls, both in urine and in DUS.

Conclusion

This new UHPLC/MS-MS method, which is suitable for rapid and easy screening of OS in urine and DUS, expands the detection of storage disorders from oligosaccharidoses to other diseases, including the novel category of inherited disorders of autophagy.

Creatine Transporter Deficiency Presenting as Autism Spectrum Disorder

Autism spectrum disorder (ASD) is the most common disability-causing neurodevelopmental disorder in childhood. Although inborn errors of metabolism (IEM) are rare causes of ASD, they are significant for several reasons, including implications in genetic counseling and determination of prognosis. In this article, we present a 6-year-old boy who presented to us with ASD and was diagnosed with creatine transporter deficiency. Physical and neurologic examination of this patient had not previously raised suspicion of IEM, but twin pregnancy, prematurity, NICU stay due to necrotizing enterocolitis, transient infantile hypotonia, gross-motor delay, breath-holding spells, and a single febrile seizure complicated the history. MRI revealed mild T2-hyperintensity in posterior periventricular white matter. Further evaluation with magnetic resonance spectroscopy, which showed a decreased creatine peak, led to diagnostic investigations for disorders of creatine metabolism, revealing increased urinary creatine:creatinine ratio and a de novo, novel hemizygous frameshift variant in SLC6A8 Clinicians are advised to maintain a high index of suspicion for IEM and to evaluate patients with ASD for syndromic features. Although current guidelines from relevant organizations differ in their recommendations regarding the necessity and the extent of metabolic screening in ASD, there is a growing trend toward screening for treatable IEM. In this case report, we present challenges and pitfalls in the diagnostic journey for creatine transporter deficiency and underline the significance of a thorough history and physical examination in the evaluation of a child with ASD.

Glutaric aciduria type 1: Genetic and phenotypic spectrum in 53 patients

INTRODUCTION

Glutaric aciduria type 1 (GA1) is a rare and inherited autosomal-recessive metabolic disorder that occurs in the deficiency of glutaryl-co-enzyme A dehydrogenase (GCDH) enzyme encoded by GCDH gene. In this study, we aim to retrospectively investigate the clinical, biochemical, and neuroradiological parameters and examine the spectrum of GCDH gene variants in Turkish patients with glutaric aciduria type 1.

METHODS

This is a descriptive cross-sectional study. The study was conducted in fifty-three patients from 39 unrelated Turkish families who were diagnosed with GA1 based on their clinical presentation, neuroimaging, and biochemical measurements, at the department of pediatric metabolism of a university hospital between June 1998 and August 2019. Pathogenic variants screening of GCDH gene was performed by direct DNA sequence analysis in forty-six patients with GA1. Pathogenicity of the novel variants was predicted via computational programs.

RESULTS

A total of 53 patients were diagnosed with GA1. Of those, 32 (60.3%) had encephalopathic crisis and 33 (62.3%) had macrocephaly. Twenty different pathogenic variants were detected, 7 of which are novel (p.Glu57Lys, p.Ser145Profs*79, p.Ser246Glyfs*96 p.Ala293Val, p.His348Gln, p.His417Tyr, p.Asp418Val). The p.Arg402Trp, p.Pro248Leu and p.Leu340Phe variants were the most common in Turkish patients, with a frequency of 21.2%, 18.2% and 12.1% respectively.

CONCLUSION

This study is the first comprehensive research from Turkey that provides information about disease-causing variants in the GCDH gene. The identification of common variants and hot spot regions of the GCDH gene is important for genetic counselling and the prenatal diagnosis of Turkish patients with GA1.

Predictors of acute metabolic decompensation in children with maple syrup urine disease at the emergency department

Acute metabolic decompensation (AMD) of maple syrup urine disease (MSUD) must be promptly recognized and treated. In this study, we aimed to identify simple variables associated with AMD in children with MSUD for use in emergency settings. Data were collected retrospectively from 115 emergency visits of 29 children with MSUD over a 4-year period in a major referral hospital. Variables in visits with and without AMD were compared using t test, Mann-Whitney U test, and chi-square test. Logistic regression was used to identify independent variables associated with decompensations. Cut-off values of laboratory variables were determined with receiver operating characteristic curves and correlations with Spearman's rank correlation. Most important variables independently associated with AMD were poor feeding, malaise, anion gap, and especially uric acid, which correlated with leucine levels. Vomiting, dehydration, neurological signs, ketonuria, and ketoaciduria were also associated with AMD. Although sodium, chloride, and glucose were lower in AMD, they had little diagnostic value.Conclusion: In children with MSUD, uric acid and anion gap are key markers for AMD. Poor feeding and malaise are clues before the onset of neurological symptoms. These simple parameters can help determine the presence of AMD in emergency settings.What is Known:• In maple syrup urine disease, acute metabolic decompensations are characterized by gastrointestinal and neurological findings.• Diagnosis requires detection of significantly elevated leucine, which may take a long time or not be available.What is New:• Poor feeding, malaise, hyperuricemia, and high anion gap are parameters that can help diagnose acute decompensations in children with maple syrup urine disease at emergency departments.• Uric acid may be a biomarker for acute decompensations because of its high sensitivity, specificity, and its strong correlation with leucine.

PKU dietary handbook to accompany PKU guidelines

Background

Phenylketonuria (PKU) is an autosomal recessive inborn error of phenylalanine metabolism caused by deficiency in the enzyme phenylalanine hydroxylase that converts phenylalanine into tyrosine.

Main body

In 2017 the first European PKU Guidelines were published. These guidelines contained evidence based and/or expert opinion recommendations regarding diagnosis, treatment and care for patients with PKU of all ages. This manuscript is a supplement containing the practical application of the dietary treatment.

Conclusion

This handbook can support dietitians, nutritionists and physicians in starting, adjusting and maintaining dietary treatment.

Two cases of Vici syndrome presenting with corpus callosum agenesis, albinism, and severe developmental delay

BACKGROUND

Vici syndrome is a rare autosomal recessive disease with phenotypically heterogeneous presentation. Characteristic features of the disease are oculocutaneous albinism, corpus callosum agenesis, cataract, cardiomyopathy, and immunodeficiency.

CASE

Here we report two Turkish patients with Vici syndrome. One of these patients had a novel mutation in EPG5 and presented with idiopathic thrombocytopenic purpura (ITP) and maculopapular rashes similar to Stevens-Johnson syndrome, which has been previously reported in only a few cases in the literature.

CONCLUSION

Vici syndrome presents with a typical phenotype which may facilitate diagnosis for infants with multisystemic disorders. ITP and maculopapular rashes might be added to the spectrum of findings of patients with Vici syndrome.

Genotypes and estimated prevalence of phosphomannomutase 2 deficiency in Turkey differ significantly from those in Europe

Phosphomannomutase 2 deficiency (PMM2-CDG) is an autosomal recessive congenital disorder of glycosylation, characterized by multisystem phenotypes, mostly including neurological involvement. In Turkey, due to high rates of consanguinity, many patients with autosomal recessive disorders have homozygous variants and these diseases are more common, compared to Europe. However, published reports of PMM2-CDG from Turkey are scarce. Here, we describe clinical and molecular characteristics of PMM2-CDG patients diagnosed in three centers in Turkey, using data obtained retrospectively from hospital records. We also analyzed an in-house exome database of 1,313 individuals for PMM2 variants and estimated allele, carrier and disease frequencies, using the Hardy-Weinberg law. Eleven patients were identified from 10 families, displaying similar characteristics to previous publications, with the exception of the first report of epilepsia partialis continua and increased prevalence of sensorineural hearing loss. p.Val231Met was the most common variant, and was homozygous in four patients. This novel genotype results in a neurological phenotype with subclinical visceral involvement. Exome database analysis showed an estimated prevalence of 1:286,726 for PMM2-CDG, which is much lower than expected (1:20,000 in Europe) because of the lack of predominance of the common European p.Asp141His allele, associated with a severe phenotype (allele frequency of 1:2,622 compared to 1:252 in gnomAD). These data suggest that prevalence, phenotypes and genotypes of PMM2-CDG in Turkey differ significantly from those in Europe: Milder phenotypes may be more common, but the disease itself rarer, requiring a higher clinical suspicion for diagnosis. The association of sensorineural hearing loss with PMM2-CDG warrants further study.

Determinants of Riboflavin Responsiveness in Multiple Acyl-CoA Dehydrogenase Deficiency

BACKGROUND

Multiple acyl-CoA dehydrogenase (MADD) deficiency, which is a rare metabolic disorder involving electron transport flavoproteins, has a wide array of clinical phenotypes. In this article, we describe 25 patients with MADD deficiency and present the clinical and laboratory characteristics and diagnostic challenges associated with riboflavin-responsive MADD deficiency.

METHODS

Hospital records of patients with biallelic mutations in ETFA, ETFB, or ETFDH genes diagnosed in a single center were analyzed retrospectively. Demographic, clinical, and laboratory characteristics of patients with riboflavin-responsive and riboflavin-unresponsive MADD deficiency were compared using Mann-Whitney U and Fisher's exact tests.

RESULTS

Respiratory distress and depressed consciousness were significantly more common in patients with riboflavin-unresponsive MADD deficiency (P = 0.015 and P < 0.001), who presented at a younger age (P < 0.001). Patients with riboflavin-responsive MADD deficiency had favorable outcomes but also had life-threatening complications, longer diagnostic delay (median of two years versus 30 days; P < 0.001), and multiple differential diagnoses, resulting in unnecessary investigations and maltreatment. Biopsies showed lipid storage, and complete autopsy was performed in one newborn with riboflavin-unresponsive MADD deficiency, revealing multiple abnormalities. Metabolic profiles were not distinguishable between riboflavin-responsive and riboflavin-unresponsive MADD deficiency (P > 0.05). Four novel variants were detected in ETFDH, one of which (c.1790C>T) may confer riboflavin responsiveness. Siblings with the common myopathic ETFDH c.1130T>C mutation presented with a new phenotype dominated by chronic fatigue without apparent myopathy.

CONCLUSIONS

Symptoms and outcomes significantly differed between riboflavin-responsive and unresponsive MADD deficiency, but metabolic profiles did not. Functional studies are needed to better characterize the novel ETFDH variants. As treatment is available for riboflavin-responsive MADD deficiency, physicians should maintain a high index of suspicion for MADD deficiency in all age groups.

Do not Miss Rare and Treatable Cause of Early-Onset Hemolytic Uremic Syndrome: Cobalamin C Deficiency

The most common disorder of vitamin B12 metabolism is methylmalonic aciduria and homocystinuria type cobalamin C (cblC), which accounts for most of the cases is referred to as cblC deficiency. Cobalamin deficiency is one of the causes of early-onset hemolytic uremic syndrome (HUS). Here, we present the cases of 2 infants with cobalamin deficiency who presented with early-onset HUS. The first patient was a 5-month-old female who was admitted to the hospital with seizure, pallor, and yellow-colored diarrheal stools. Initial laboratory examination showed direct Coombs test-negative hemolytic anemia. Later, she developed acute kidney injury and thrombocytopenia. Bone marrow aspiration showed megaloblastic features, and urinary examination showed elevated levels of methylmalonic acid (MMA), -methyl citrate, and 3-hydroxypropionic acid. Methionine-restricted diet, parenteral hydroxocobalamine, folinic acid, carnitine, and betaine were initiated. Hemolytic activity was -controlled with this treatment. Genetic screening showed homozygous mutation on the MMACHCgene (p.R161*[c.481C>T]). The second patient was a 3-month-old male infant who was admitted to the hospital with malaise and diarrhea. Laboratory examination showed direct Coombs test-negative hemolytic anemia with leukopenia. Later he developed acute kidney injury and thrombocytopenia. Bone marrow aspiration revealed megaloblastic changes. Urine organic acid test showed increased levels of MMA. Parenteral hydroxocobalamine, folinic acid, carnitine, and betaine were initiated. He died due to respiratory failure and cardiac arrest. Direct sequencing of MMACHC identified homozygous mutation, c.271dup A. CblC deficiency is an important cause of early-onset HUS and prompt diagnosis will provide specific treatment modalities.

Do not Miss Rare and Treatable Cause of Early-Onset Hemolytic Uremic Syndrome: Cobalamin C Deficiency

The most common disorder of vitamin B12 metabolism is methylmalonic aciduria and homocystinuria type cobalamin C (cblC), which accounts for most of the cases is referred to as cblC deficiency. Cobalamin deficiency is one of the causes of early-onset hemolytic uremic syndrome (HUS). Here, we present the cases of 2 infants with cobalamin deficiency who presented with early-onset HUS. The first patient was a 5-month-old female who was admitted to the hospital with seizure, pallor, and yellow-colored diarrheal stools. Initial laboratory examination showed direct Coombs test-negative hemolytic anemia. Later, she developed acute kidney injury and thrombocytopenia. Bone marrow aspiration showed megaloblastic features, and urinary examination showed elevated levels of methylmalonic acid (MMA), -methyl citrate, and 3-hydroxypropionic acid. Methionine-restricted diet, parenteral hydroxocobalamine, folinic acid, carnitine, and betaine were initiated. Hemolytic activity was -controlled with this treatment. Genetic screening showed homozygous mutation on the MMACHCgene (p.R161*[c.481C>T]). The second patient was a 3-month-old male infant who was admitted to the hospital with malaise and diarrhea. Laboratory examination showed direct Coombs test-negative hemolytic anemia with leukopenia. Later he developed acute kidney injury and thrombocytopenia. Bone marrow aspiration revealed megaloblastic changes. Urine organic acid test showed increased levels of MMA. Parenteral hydroxocobalamine, folinic acid, carnitine, and betaine were initiated. He died due to respiratory failure and cardiac arrest. Direct sequencing of MMACHC identified homozygous mutation, c.271dup A. CblC deficiency is an important cause of early-onset HUS and prompt diagnosis will provide specific treatment modalities.

International best practice for the evaluation of responsiveness to sapropterin dihydrochloride in patients with phenylketonuria

Phenylketonuria (PKU) is an inherited metabolic disease caused by phenylalanine hydroxylase (PAH) deficiency. As the resulting high blood phenylalanine (Phe) concentration can have detrimental effects on brain development and function, international guidelines recommend lifelong control of blood Phe concentration with dietary and/or medical therapy. Sapropterin dihydrochloride is a synthetic preparation of tetrahydrobiopterin (6R-BH4), the naturally occurring cofactor of PAH. It acts as a pharmacological chaperone, reducing blood Phe concentration and increasing dietary Phe tolerance in BH4-responsive patients with PAH deficiency. Protocols to establish responsiveness to sapropterin dihydrochloride vary widely. Two meetings were held with an international panel of clinical experts in PKU management to develop recommendations for sapropterin dihydrochloride response testing. At the first meeting, regional differences and similarities in testing practices were discussed based on guidelines, a literature review, outcomes of a global physician survey, and case reports. Statements developed based on the discussions were sent to all participants for consensus (>70% of participants) evaluation using a 7-level rating system, and further discussed during the second meeting. The experts recommend sapropterin dihydrochloride response testing in patients with untreated blood Phe concentrations of 360-2000 μmol/L, except in those with two null mutations. For neonates, a 24-h sapropterin dihydrochloride loading test is recommended; responsiveness is defined as a decrease in blood Phe ≥30%. For older infants, children, adolescents, and adults, a test duration of ≥48 h or a 4-week trial is recommended. The main endpoint for a 48-h to 7-day trial is a decrease in blood Phe, while improved Phe tolerance is the endpoint to be assessed during a longer trial. Longer trials may not be feasible in some locations due to lack of reimbursement for hospitalization, while a 4-week trial may not be possible due to limited access to sapropterin dihydrochloride or public health regulation. A 48-h response test should be considered in pregnant patients who cannot achieve blood Phe ≤360 μmol/L with a Phe-restricted diet. Durability of response and clinical benefits of sapropterin dihydrochloride should be assessed over the long term. Harmonization of protocols is expected to improve identification of responders and comparability of test results worldwide.

Genotypic-phenotypic features and enzyme replacement therapy outcome in patients with mucopolysaccharidosis VI from Turkey

Mucopolysaccharidosis type VI (MPS VI) is a lysosomal storage disorder (LSD) characterized by a chronic, progressive course with multiorgan involvement. In our study, clinical, biochemical, molecular findings, and response to enzyme replacement therapy (ERT) for at least 6 months were evaluated in 20 patients with MPS VI. Treatment effects on clinical findings such as liver and spleen sizes, cardiac and respiratory parameters, visual and auditory changes, joints' range of motions, endurance tests and changes in urinary glycosaminoglycan excretions, before and after ERT were analyzed. ERT caused increased physical endurance and decreased urinary dermatan sulfate/chondroitin sulfate ratios. Changes in growth parameters, cardiac, respiratory, visual, auditory findings, and joint mobility were not significant. All patients and parents reported out an increased quality of life, which were not correlated with clinical results. The most prevalent mutation was p.L321P, accounting for 58.8% of the mutant alleles and two novel mutations (p.G79E and p.E390 K) were found. ERT was a safe but expensive treatment for MPS VI, with mild benefits in severely affected patients. Early treatment with ERT is mandatory before many organs and systems are involved.

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.

Detection of biotinidase gene mutations in Turkish patients ascertained by newborn and family screening

The incidence of biotinidase deficiency in Turkey is currently one of the highest in the world. To expand upon the information about the biotinidase gene (BTD) variations in Turkish patients, we conducted a mutation screening in a large series (n = 210) of probands with biotinidase deficiency, using denaturing high-performance liquid chromatography and direct DNA sequencing. The putative effects of novel mutations were predicted by computational program. Twenty-six mutations, including six novels (p.C143F, p.T244I, c.1212-1222del11, c.1320delG, p.V457L, p.G480R) were identified. Nine of the patients were symptomatic at the initial clinical assessment with presentations of seizures, encephalopathy, and lactic acidemia. The most common mutation in this group of symptomatic patients was c.98-104 del7ins3. Among the screened patients, 72 have partial and 134 have profound biotinidase deficiency (BD) of which 106 are homozygous for BTD mutations. The common mutations (p.R157H, p.D444H, c.98-104del7ins3, p.T532M) cumulatively accounted for 72.3% of all the mutant alleles in the Turkish population.

CONCLUSION

The identification of common mutations and hot spot regions of the BTD gene in Turkish patients is important for mutation screening in the Turkish population and helps to ascertain carriers, may have impact on genetic counseling and implementing prevention programs.

Two Turkish siblings with MEGDEL syndrome due to novel SERAC1 gene mutation

Association of 3-methylglutaconic aciduria with impaired oxidative phosphorylation, deafness, encephalopathy, leigh-like lesions on brain imaging, progressive spasticity and dystonia defined as a distinct entity under the name of MEGDEL syndrome. It is an autosomal recessive disorder due to mutation in the serine active site-containing protein 1 (SERAC1). SERAC1 is localized at the interface between the mitochondria and the endoplasmic reticulum in the mitochondria-associated membrane fraction that is essential for phospholipid exchange. It was identified as a key player in the phosphatidylglycerol remodeling that is essential for both mitochondrial function and intracellular cholesterol trafficking. Here we report two new Turkish sibling patients affected with MEGDEL syndrome due to SERAC1 gene mutation. The patients were presented with 3-methylglutaconic acid and 3-methylglutaric aciduria, microcephaly, growth retardation, dysmorphic features, severe sensorineural deafness, progressive spasticity, dystonia, seizures, basal ganglia involvement. Metabolic acidosis, mild hyperammonemia and lactic acidemia were accompanied with clinical findings in newborn period.

Sapropterin dihydrochloride treatment in Turkish hyperphenylalaninemic patients under age four

Sapropterin enhances phenylalanine hydroxylase activity, thus lowering blood phenylalanine (Phe) concentration while increasing protein tolerance in sapropterin-responsive patients. Initiation of sapropterin treatment in responsive patients as early as possible, especially during the time when brain development is fastest, allows intake of more natural protein as well as micro- and macronutrients. Initiation of sapropterin treatment in the newborn period can make exclusive breastfeeding possible. Reports on the efficacy and safety of sapropterin in phenylketonuria (PKU) children under age four are limited in the literature. The purpose of this study is to evaluate the efficacy and safety of sapropterin treatment in infants and children with hyperphenylalaninemia (HPA) and to assess whether genotype analyses are of help in the prediction of responsiveness in these children. Clinical features as well as dietary characteristics were examined in 44 patients undergoing sapropterin treatment. Molecular genetic analysis was performed in 28 of these patients. Phe tolerance increased a median of 2.26-fold (0.88-4.23), from a median of 47.5 mg/kg/day to a median of 114 mg/kg/day (p<0.001). Phe levels could not be kept within normal limits in 5 patients, and thus treatment was stopped due to unsatisfactory metabolic control. In 9 patients, sapropterin treatment was started prior to the initiation of a Phe-restricted diet. Sapropterin treatment was found to be safe and efficacious in patients under age four. Although the BH4 loading test and molecular genetic analysis proved to be useful in detecting responsive patients, these analyses did not enable us to make predictions as to long-term responsiveness.

Conventional and advanced MR imaging in infantile Refsum disease

We report magnetic resonance (MR) imaging findings including diffusion-weighted imaging and proton MR spectroscopy findings in a patient with infantile Refsum disease. The initial diagnosis was made on the basis of history, clinical findings and biochemical studies. Bilateral and symmetrical involvement of the peritrigonal white matter, centrum semiovale, thalami, corpus callosum and corticospinal tracts as assessed by increased T2 signal was highly suggestive of a peroxisomal disorder. Facilitated diffusion was observed in diseased parenchyma. Long echo-time (TE: 270 ms) MRS showed decreased N-acetyl-aspartate/creatine and elevated choline/creatine and lactate; short echo-time MRS (TE: 30 ms) revealed increased myoinositol at 3.56 ppm and lipid peaks at 0.9 and 1.3 ppm. A major contribution to the differential diagnosis came from MR imaging and proton MRS, as discussed in this report.

Cobalamin C defect: a patient of late-onset type with homozygous p.R132* mutation

Methylmalonic aciduria and homocystinuria, cobalamin C (cblC) type, is the most frequent inborn error of vitamin B12metabolism. The clinical phenotype includes systemic symptoms and neurological decompensation. Affected patients can be divided into two broad groups, as early-onset and late-onset. We present a Turkish patient who had neurological impairment at the age of four years as presented with late-onset cblC defect. Homozygous c.394C<T; p.R132* mutation in the MMACHC gene was detected. The patient was treated with hydroxocobalamin, betaine and folic acid combination with good clinical and biochemical response.

Genetic basis of hyperlysinemia

BACKGROUND

Hyperlysinemia is an autosomal recessive inborn error of L-lysine degradation. To date only one causal mutation in the AASS gene encoding α-aminoadipic semialdehyde synthase has been reported. We aimed to better define the genetic basis of hyperlysinemia.

METHODS

We collected the clinical, biochemical and molecular data in a cohort of 8 hyperlysinemia patients with distinct neurological features.

RESULTS

We found novel causal mutations in AASS in all affected individuals, including 4 missense mutations, 2 deletions and 1 duplication. In two patients originating from one family, the hyperlysinemia was caused by a contiguous gene deletion syndrome affecting AASS and PTPRZ1.

CONCLUSIONS

Hyperlysinemia is caused by mutations in AASS. As hyperlysinemia is generally considered a benign metabolic variant, the more severe neurological disease course in two patients with a contiguous deletion syndrome may be explained by the additional loss of PTPRZ1. Our findings illustrate the importance of detailed biochemical and genetic studies in any hyperlysinemia patient.

Serum alpha-fetoprotein levels in neonatal cholestasis

Alpha-fetoprotein (AFP) is used as a tumor marker for hepatocellular carcinoma, hepatoblastoma and germ cell tumors. It may also be elevated in infants with some hepatobiliary disorders. The mechanism of AFP elevation in neonatal cholestasis is not known. We retrospectively evaluated serum AFP levels in 53 infants with neonatal cholestasis. Thirty patients (56.6%) had elevated AFP, and the ratio of patients with elevated AFP was significantly high in both the metabolic diseases and idiopathic neonatal hepatitis groups (p=0.021). Serum aspartate aminotransferase (AST) levels increased significantly in patients with elevated AFP (p=0.004). Steatosis was the distinctive histopathological finding of the patients with high AFP. The patients with steatosis had significantly higher standard deviation (SD) score of AFP than the patients without steatosis (p=0.001). We have shown AFP elevation in neonatal cholestasis due to metabolic disorders and idiopathic neonatal hepatitis and its association with steatosis and AST elevation.

Microarray based mutational analysis of patients with methylmalonic acidemia: identification of 10 novel mutations

Methylmalonic acidemia is an autosomal recessive metabolic disorder affecting the propionate oxidation pathway in the catabolism of several amino acids, odd-chain fatty acids, and cholesterol. Methylmalonic acidemia is characterized by elevated levels of methylmalonic acid in the blood and urine. Mutations in the MUT gene, encoding methylmalonyl-CoA mutase carries out isomerization of L-methylmalonyl-CoA to succinyl-CoA, cause methylmalonic acidemia. In this study, 30 Turkish patients diagnosed with mut methylmalonic acidemia were screened for mutations using custom designed sequencing microarrays. The study resulted in detection of 22 different mutations, 10 of which were novel: p.Q132*, p.A137G, c.753+1T, p.T387I, p.Q514E, p.P615L, p.D625V, c.1962_1963delTC, p.L674F, and c.2115_2116insA. The most common, p.P615T, was identified in 28.0% of patients. These results suggest that microarray based sequencing is a useful tool for the detection of mutations in MUT in patients with mut methylmalonic acidemia.

Detection of other inborn errors of metabolism in hyperphenylalaninemic babies picked up on narrow-spectrum screening programs

In many countries, neonatal screening programs have been unable to expand and have been limited to a few diseases. We highlight herein the opportunity available for the early detection of some inborn errors of metabolism (IEMs) in those countries in which newborn screening programs are limited. All the newborns that are referred to us for hyperphenylalaninemia are examined physically and their blood samples are checked by both high-performance liquid chromatography (HPLC) for blood phenylalanine levels and by amino acid analyzer for the measurement of blood amino acid concentrations. Seven patients who had been referred to our unit for hyperphenylalaninemia were eventually diagnosed with another IEM. A careful physical examination of the babies sent for positive screening test result combined with the utilization of low expense screening techniques at the experienced referring centers might facilitate otherwise missed opportunities for the early detection of some IEMs.

When do we need to perform a diagnostic lumbar puncture for neurometabolic diseases? Positive yield and retrospective analysis from a tertiary center

Neurometabolic diseases diagnosed by cerebrospinal fluid (CSF) examination are GLUT1 deficiency, serine-deficiency syndromes, glycine encephalopathy, cerebral folate deficiency, neonatal vitamin-responsive epileptic encephalopathies, disorders of monoamine metabolism, and y-amino butyric acid (GABA) metabolism. We retrospectively analyzed and compared the demographic, clinical, laboratory, and neuroimaging features of 62 patients in whom CSF examination was performed. Of the 62 patients, 16 (25.8%) had a final diagnosis, including succinic semialdehyde dehydrogenase (SSADH) deficiency (n=4), aromatic amino acid decarboxylase (AADC) deficiency (n=4), L-dopa-responsive dystonia (n=3), glycine encephalopathy (n=2), pyridoxal-phosphate-dependent seizures (n=l), cerebral folate deficiency (n=1), and serine biosynthesi defect (n=1). Parental consanguinity was present in all patients except one Positive yield of a diagnostic lumbar puncture (LP) for the diagnosis of inherited neurotransmitter metabolism disorder was 25.8% overall. Oculogyric crisis (50%), diurnal variation (81.8%) and consanguinity (93.8%) were the only statistically significant variables between patients with and without a specific diagnosis. It is challenging to diagnose neurotransmitter defects, since there is no ideal set of clinical symptoms. In our cohort, consanguinity, diurnal variation and abnormal ocular movements were the most significant findings associated with a diagnosis of a specific neurometabolic disorder based on CSF examination. Early diagnosis is of great importance not only for specific treatment, but also for genetic counseling and prenatal diagnosis.

Identification of mutations and evaluation of cardiomyopathy in Turkish patients with primary carnitine deficiency

Primary systemic carnitine deficiency (SCD) is an autosomal recessive disorder caused by defective cellular carnitine transport. Patients usually present with predominant metabolic or cardiac manifestations. SCD is caused by mutations in the organic cation/carnitine transporter OCTN2 (SLC22A5) gene. Mutation analysis of SLC22A5 gene was carried out in eight Turkish patients from six families. Six patients presented with signs and symptoms of heart failure, cardiomyopathy, and low plasma carnitine levels, five of them with concurrent anemia. A patient with dilated cardiomyopathy had also facial dysmorphia, microcephaly, and developmental delay. Tandem MS analyses in siblings of the patients revealed two more cases with low plasma carnitine levels. SCD diagnosis was confirmed in these two cases by mutation screening. These two cases were asymptomatic but echocardiography revealed left ventricular dilatation in one of them. Carnitine treatment was started before the systemic signs and symptoms developed in these patients. Mean value of serum carnitine levels of the patients was 2.63±1.92μmol/L at the time of diagnosis. After 1year of treatment, carnitine values increased to 16.62±5.11 (p<0.001) and all responded to carnitine supplementation clinically. Mutation screening of the OCTN2 gene study in the patients revealed two novel (p.G411V, p.G152R), and four previously identified mutations (p.R254X, p.R282X, p.R289X, p.T337Pfs12X). Early recognition and carnitine supplementation can be lifesaving in this inborn error of fatty acid oxidation.

Mutation spectrum of fumarylacetoacetase gene and clinical aspects of tyrosinemia type I disease

Tyrosinemia type I (OMIM 276700) is a rare, autosomal recessive disorder caused by a deficiency in the fumarylacetoacetate hydrolase (FAH) enzyme. This study examined the spectrum of FAH gene mutation in 32 patients with tyrosinemia type I. In addition, clinical and biochemical findings were evaluated to establish a genotype-phenotype relationship in the patients. Mutation screening was performed using a 50K custom-designed resequencing microarray chip (TR_06_01r520489, Affymetrix) and sequencing analysis. Of the 12 different mutations found, 6 are categorized as novel. Three of the mutations-IVS6-1G>A, D233V, and IVS3-3C>G-are the most common in Turkish patients, comprising 25%, 17.1%, and 12.5% of mutant alleles, respectively.Clinical evaluations suggest that the spectrum of symptoms observed in the patients with very early and early disease were of the more nonspecific form, whereas the patients with late-presenting disease had more of the distinctive form over the course of the disease. This study adds support to the notion that the D233V mutation is specific to the Turkish population.

Zinc supplementation and TNF-α levels in vaccinated cardiac patients

OBJECTIVE

To investigate whether zinc supplementation could affect serum tumor necrosis factor-alpha (TNF-α) levels in congenital and acquired cardiac patients attending for an influenza vaccine.

METHODS

9-18 years old, voluntary children with cardiac disease were weighed, measured height and blood samples for hemoglobin level, zinc level, IgA and IgG titers of influenza A and B serotypes and TNF-α levels were obtained. The children were randomly assigned to 1 of 2 groups: ZV group received both zinc supplementation and influenza vaccine; V group received influenza vaccine. Serum TNF-α levels were measured at 28 days after the immunization.

RESULTS

Mean (±SD) serum zinc level was 100 (±20) μg/dL. Cases with congenital heart disease had lower serum zinc levels than acquired ones (93±17 μg/dL, 116±18 μg/dL; respectively, p<0.001). Median titers of serum TNF-α decreased after vaccination (78.9 pg/mL, 74.8 pg/mL; p<0.05) but this significant change occurred only in ZV group (77.1 pg/mL, 73.4 pg/mL; p=0.001). Vaccine associated adverse events were similar in ZV and V groups except malaise (0% in ZV and 23.8% in V group; p<0.05). Adverse events were similar in patients with congenital and acquired heart diseases. During the previous influenza season, 77.3% had more than two episodes of upper respiratory tract infection (URTI), however, after vaccination only 13.6% had more than two episode of URTI.

CONCLUSION

Zinc supplementation has a beneficial effect on malaise, one of the influenza vaccine associated adverse events, and decrease serum TNF-α levels.

Home visits in phenylketonuria: a 12-month longitudinal study

This study aimed to evaluate the effect of dietary education given to the caregivers of children with phenylketonuria (PKU) in their home environment on children's blood phenylalanine (Phe) levels. Thirty-six children with PKU, aged 2-12 years, were recruited. Each caregiver was visited on three separate occasions and given a detailed dietary education. Fasting morning skin puncture blood samples were collected on Newborn Screening Blood Test filter paper for Phe analysis at baseline and 1, 4, 12, 24, and 48 weeks after the home visits. The mean baseline blood Phe level (365 +/- 232 micromol/L) significantly decreased with home visits at the 1st week (314 +/- 226 micromol/L) (p < 0.05). Four weeks after the home visits, the median blood Phe level was still lower than baseline, but the difference was not statistically significant (p > 0.05). The mean blood Phe levels significantly increased at the end of the 12th, 24th and 48th weeks (329 +/- 230 micromol/L; 447 +/- 189 micromol/L and 486 +/- 261 micromol/L, respectively) (p < 0.05). A well-controlled blood Phe level can be achieved with intense, regular and continuing education programs, which include regular home visits.

A novel mutation in the DGUOK gene in a Turkish newborn with mitochondrial depletion syndrome

Deoxyguanosine kinase (DGUOK) catalyzes the first step of the mitochondrial deoxypurine salvage pathway, the phosphorylation of purine deoxyribonucleosides. Mutations in the DGUOK gene have been linked to inherited mitochondrial (mt)DNA depletion syndromes, neonatal liver failure, nystagmus, and hypotonia. We now report a novel homozygous c.34C > T (p.Arg12X) mutation found in an affected newborn of asymptomatic consanguineous parents. Respiratory distress started in the first hours after birth. The patient died at the age of 42 days due to liver failure. This genotype, which is to be expected for a homozygous stop codon mutation in exon 1, is associated with a severe clinical presentation.

Gyrate atrophy of the choroid and retina: a case report

Gyrate atrophy is a rare metabolic disease characterized by hyperornithinemia, typical retinal and choroidal lesions, high myopia with marked astigmatism, early cataract formation, and autosomal recessive inheritance pattern. In this paper, we describe a 12-year-old boy presenting with high myopia and gyrate fundus lesions, in addition to 10-times elevated serum ornithine level.

Antihyperlipidemic agents cause a decrease in von Willebrand factor levels in pediatric patients with familial hyperlipidemia

Familial hyperlipidemia is a group of genetic disorders with a predisposition to atherosclerosis. Hyperlipidemia causes increased atherosclerotic events through increased endothelial damage. In this report we aimed to measure the plasma fibrinogen and von Willebrand factor antigen (VWf:Ag) levels in pediatric patients with familial hyperlipidemias and to investigate the effects of serum lipid levels and antihyperlipidemic agents on these parameters. Of the 41 patients analyzed, vWf:Ag level was significantly lower in antihyperlipidemic receivers (132 +/- 51%, 102 +/- 19%; p = 0.010). This finding may indicate that early initiation of antihyperlipidemics in patients with familial hyperlipidemias may decrease the risk of future atherosclerotic events through not only decreasing the serum lipid levels, but also decreasing plasma vWf:Ag levels.

The urinary cotinine levels of infants and the determinants

The aim of this study was to determine the effect of the route of tobacco smoke exposure on urinary cotinine levels of infants. A cross-sectional analysis was done on 254 six-month-old infants. The infants were grouped according to the route of tobacco smoke exposure. The urinary cotinine/creatinine ratios were determined. Forty-nine percent (124/254) of mothers were smokers. Urinary cotinine levels in infants of smoking mothers were statistically significantly higher than levels in infants of non-smoking mothers. The highest mean cotinine/creatinine level was found in the breast-milk-exposed group. Linear regression analysis showed that maternal smoking increased urinary cotinine level by 541 times and breastfeeding increased it by 171 times, whereas early start of formula feeding decreased it by 63 times. Tobacco exposure by breastfeeding may be more harmful than other routes of exposure. Mothers should be encouraged to stop smoking during the breastfeeding period even if they avoid exposing their infants to passive tobacco smoke.

The relationship between vitamin D receptor gene polymorphisms and bone density, osteocalcin level and growth in adolescents

BACKGROUND/OBJECTIVE

The relationship between vitamin D receptor gene polymorphisms and bone density, osteocalcin and growth was investigated.

SUBJECTS

Eighty eight adolescents aged between 8-15, with no history of illness influencing the level of bone parameters, were examined in our study.

METHODS

Areal BMD for lumbar spine (L1-4) was assessed by dual energy X-ray absorptiometry (DEXA). Height and weight were measured on the day of the DEXA scans. Serum osteocalcin level was determined by using ELISA method. DNA was extracted from white blood cells, amplified by the polymerase chain reaction (PCR) and the polymorphic sites were analyzed by using ApaI, TaqI and FokI restriction enzymes.

RESULTS

The most frequent genotypes were FF (% 54.6), Aa (% 53.4) and Tt (% 48.8). No significant relationship was found between VDR genotypes and areal BMD, osteocalcin level or growth in either sex. But there was a strong tendency for a higher BMD at the lumbar spine of TT and AA genotypes compared to tt and Aa genotypes. The children with TT genotype were taller and heavier than the children with tt genotype

CONCLUSION

Our results suggest that VDR gene TaqI polymorphism may be associated with body weight and bone mass, but more studies with larger groups should be conducted.

Maternal and environmental determinants of breast-milk mercury concentrations

We aimed to evaluate the maternal factors [including dietary habits, dental care, smoking, anemia, levels of breast-milk zinc (Zn) and iron (Fe), and levels of serum selenium (Se), Zn and copper (Cu)] that influence breast-milk mercury (Hg) concentrations and to investigate whether there is any relation between Hg concentrations and infant growth and development during the exclusive breastfeeding period and in the second year of life. Forty-four healthy mother-infant pairs in the 10-20-day postpartum period were enrolled in the study. Maternal history and blood samples for hemoglobin, Fe, Fe binding capacity, ferritin, Se, Zn, and Cu and breast-milk samples for Fe, Zn and Hg were taken. Infant growth and development during the exclusive breastfeeding period and in the second year of life were followed. The mean concentration of breast-milk Hg was 3.42 +/- 1.66 microg/L. Serum Se levels were negatively correlated with milk Hg levels. Multivariate analysis revealed that active/passive smoking and offal intake during pregnancy and presence of maternal anemia had an impact on increased milk Hg concentrations. Preventive strategies for mercury exposure should include management of iron deficiency anemia, cessation of smoking exposure and proper nutrition during the pregnancy period.

3-phosphoglycerate dehydrogenase deficiency: a case report of a treatable cause of seizures

Serine deficiency disorders are a new group of neurometabolic diseases resulting from a deficiency in one of the three enzymes in the biosynthetic pathway of L-serine. Deficiency of the enzyme 3-phosphoglycerate dehydrogenase (3-PGDH), which catalyzes the first step in the biosynthetic pathway, leads to congenital microcephaly, severe psychomotor retardation, and intractable seizures. We report a 4 1/2-year-old boy who presented with congenital microcephaly, psychomotor retardation, hypertonia, strabismus, and drug-resistant seizures due to 3-PGDH deficiency. His seizures responded to L-serine and glycine supplementation only. This potentially treatable disease should be borne in mind in patients with congenital microcephaly, psychomotor retardation and seizures. A timely diagnosis based on the detection of low cerebrospinal fluid levels of L-serine and glycine is expected to further increase the success of L-serine and glycine supplementation in these patients.

Effect of passive smoking on growth and infection rates of breast-fed and non-breast-fed infants

BACKGROUND

The aim of the present study was to determine the effect of passive tobacco smoking on growth and infection rate of infants, and to evaluate whether breast-feeding might be protective against harmful effects of cigarette smoke.

METHODS

A cross-sectional study on 254 6-7-month-old infants was carried out. A questionnaire was given to mothers; and infants' head circumference, bodyweight, height, and urinary cotinine levels were measured.

RESULTS

Multivariate analysis of factors influencing lower respiratory tract infections showed that smoking mothers increased the rate by 9.1-fold; breast-feeding decreased it by 3.3-fold; formula feeding at birth increased it by a factor of 15.2; another smoker at home increased it by a factor of 40.1. Multivariate analysis of factors influencing upper respiratory tract infections showed that smoking mothers increased the rate by a factor of 23; early formula feeding increased it by a factor of 62; breast-feeding decreased it by a factor of 5; smoking fathers increased it by a factor of 15. Multivariate analysis of factors influencing otitis media found that smoking mothers and fathers increased it by a factor of 9.4 and 6.15, respectively, and breast-feeding decreased it by a factor of 5.4.

CONCLUSION

Tobacco smoke exposure of infants has negative consequences on growth, otitis media, and upper and lower respiratory tract infections. Breast-feeding promoted the growth of infants who were passively exposed to tobacco smoke and protected them against infections. Smoking should not be permitted in households with infants. When this is impossible, breast-feeding should be promoted to protect the infants against the health hazards of passive smoking.

Molecular genetics of maple syrup urine disease in the Turkish population

In maple syrup urine disease (MSUD), disease-causing mutations can affect the BCKDHA, BCKDHB or DBT genes encoding for the E1alpha, E1beta and E2 subunits of the multienzyme branched-chain alpha-keto acid dehydrogenase (BCKDH) complex. Here we summarize the MSUD genotypes of a cohort of 32 unrelated Turkish patients in whom both alleles at a single gene locus harbored presumable disease-causing nucleotide changes. The patients had different forms of MSUD, ranging from the severe classical form (26 patients) to severe and mild variants (6 patients). In all except two patients (92%), the mutations occurred homozygously. The mutational spectrum included 27 different sequence variations--12 changes in the BCKDHA, 10 in the BCKDHB, and 5 in the DBT genes. In 37% (12 patients) of a total of 64 alleles, the supposed disease-causing mutations were located in the BCKDHA gene, in 44% (14 patients) in the BCKDHB gene and in 19% (6 patients) in the DBT gene. The mutational profile is heterogeneous, although two mutations occurred three times and five mutations occurred twice. There was no cluster for a single mutation except for c.773G>A (p.Cys258Tyr) in the BCKDHA gene, a hypothetical founder mutation in the Camlidere population.

Two new cases with Pearson syndrome and review of Hacettepe experience

Pearson syndrome (PS) is a mitochondrial disease and clinical presentation is rather varied. These patients are often subjected to extensive biochemical and clinical work-up for diagnosis. We report two new cases and review our experience with PS in Hacettepe University. The first case had large deletion of mitochondrial DNA (mtDNA) and presented with severe metabolic acidosis and anemia associated with hemophagocytosis in bone marrow. He also had liver involvement and tubulopathy. The second case, who had the 4997 bp common deletion, presented with anemia at 8 weeks of age followed by an uneventful 4 years. She developed very severe acidosis and renal Fanconi syndrome at the age of 4.5 years. Our cases revealed once more the clinical diversity of the disease and no correlation between the size and site of mtDNA deletion and clinical presentation. We encourage physicians to look for PS in children with early sideroblastic anemia and multiple organ system involvement.