Clinical Presentation and Molecular Characterization of 3 Patients with Vici Syndrome: Two Novel Variants in the EPG5 Gene.

Introduction: Vici syndrome is an ultra-rare, congenital disorder of autophagy characterized by agenesis of the corpus callosum, cataracts, cardiomyopathy, combined immunodeficiency, developmental delay, and hypopigmentation. Patients usually present in the neonatal period or infancy with profound hypotonia, based on information available from the nearly 100 cases reported to date. Case Presentation: We present 3 new cases of Vici syndrome confirmed by genetic analysis of EPG5 gene. The 3 male patients had neonatal hypotonia, progressive microcephaly, psychomotor retardation, recurrent respiratory tract infections, optic atrophy, and failure to thrive, but no cataracts or hepatomegaly. Three disease-causing variants in homozygous state were detected in the EPG5 gene: two novel c.1652C>T and c.7557+2T>C forms; and one previously reported c.7447C>T. The patient, who was homozygous for the c.1652C>T mutation, presented with neonatal onset seizures that had not been reported previously. Discussion/Conclusion: The present study provides data for the evaluation of the natural history and genotype-phenotype correlations for treatment options that are expected to be available in the future.

Clinical, biochemical, and molecular insights into Cerebrotendinous Xanthomatosis: A nationwide study of 100 Turkish individuals.

OBJECTIVE: Cerebrotendinous xanthomatosis (CTX) is an inherited metabolic disorder characterized by progressive neurologic and extraneurologic findings. The aim of this retrospective, descriptive study was to explore the time of presentation and diagnosis, and to expand the phenotype and genotype of CTX, based on a nationwide and comprehensive series of patients in Turkey. METHODS: The demographic, clinical, biochemical and genotypic characteristics of the CTX patients were reviewed. Data on molecular analysis, age of onset and diagnosis, diagnostic delay, neurologic and extraneurologic symptomatology, results of plasma cholestanol levels, brain magnetic resonance imaging and electromyography at the time of diagnosis were reviewed. RESULTS: 100 confirmed CTX patients from 72 families were included. The mean age at diagnosis was 28.16 ± 14.28 years, and diagnostic delay was 18.39 ± 13.71 years. 36 patients were diagnosed in childhood. Frequency of intention tremor (p = 0.069), peripheral neuropathy (p = 0.234) and psychiatric manifestations (p = 0.396) did not differ between two groups, demonstrating the high rate in pediatric patients. Three adult patients showed a milder phenotype without neurologic involvement. Seven patients had normal plasma cholestanol levels despite neurological impairment. Sequencing of the CYP27A1 gene revealed 25 different variants, with a novel c.671_672del variant not previously described in literature. CONCLUSION: Based on the observations of this Turkish CTX cohort, it is emphasized that the true prevalence of CTX is probably underestimated and that it has a wide spectrum of clinical phenotypes even without neurological impairment. In children, abnormal cerebellar findings, peripheral neuropathy and psychiatric findings associated with intellectual disability have been suggested as warning signs to avoid diagnostic delay. In cases of clinical suspicion, molecular analysis is recommended despite normal plasma cholestanol levels, as severe neurologic involvement may occur in CTX patients without elevated cholestanol levels.

Concurrent Cobalamin C and Plasminogen Deficiencies in a Patient with Chronic Thrombotic Microangiopathy.

BACKGROUND: Although most patients with atypical hemolytic uremic syndrome (aHUS) have variants in genes participating in alternative complement pathways, rare variants in non-complement pathway-related genes, including DGKE, INF2, MMACHC, PLG, and THBD, have also been described. CASE PRESENTATION: We report an 18-year-old male patient with renal biopsy-proven chronic thrombotic microangiopathy that raised suspicion of aHUS. Whole-exome sequencing revealed a novel pathogenic homozygous MMACHC c.484G>T (p.Gly162Trp) variant. Subsequently, clinical and laboratory findings confirmed cobalamin C (Cbl C) deficiency. Also, homozygous missense c.1112C>T PLG (p.Thr371Ile) variant was detected (it had been reported as a variant of unknown significance). However, the low serum plasminogen (PLG) activity proved the pathogenicity of c.1112C>T. Hence, the patient was diagnosed with concurrent Cbl C and PLG deficiencies. Segregation analysis revealed that the mother and father had the same heterozygous PLG and MMACHC variants. PLG variants have generally been described in aHUS patients concomitant with complement gene variants in the literature; therefore, the association between aHUS and PLG variants is controversial. The possible contribution of PLG deficiency to thrombotic microangiopathy was also discussed in this case. CONCLUSION: Non-complement-mediated aHUS is an exceptional disorder. A limited number of genes are involved in this entity. To our knowledge, this is the first aHUS patient diagnosed with both Cbl C and PLG deficiencies in the literature.

A different perspective into clinical symptoms in CPT I deficiency.

Carnitine palmitoyltransferase I (CPT I) deficiency is an autosomal recessive disorder causing long-chain fatty acid oxidation defect, characterized by metabolic decompensation episodes accompanied by hypoketotic hypoglycemia, hepatomegaly, seizures, renal tubular acidosis, and hyperammonemia. The aim of this study was to investigate the neurological symptoms in CPT I deficiency and different outcomes with respect to predisposing factors for sequela and to draw attention to the neurological impairment that may develop during the course of the disease. The retrospective study reviewed clinical characteristics of 14 patients. Mean follow-up period was 10.3 ± 4.7 (range: 8 months-18.6 years; median: 10 years) years. Three patients were diagnosed with newborn screening. In the symptomatic group (n = 12) most common presenting symptoms were psychomotor retardation (n = 6), seizures (n = 5), encephalopathy (n = 5), dystonia (n = 1), Reye-like syndrome (n = 5), muscle weakness (n = 3), and autism (n = 1). Neurologic findings detected in the follow-up period included speech disorder (n = 9), abnormal cranial MRI findings (n = 5), neuropathy (n = 1), and attention deficit hyperactivity disorder (n = 1). Speech disorders collectively included delayed expressive language development, speech articulation disorder, speech delay, stuttering, and specific speech difficulties. After starting treatment for CPT I deficiency, speech disorders improved in 3 patients. Our findings confirmed that the clinical manifestations of CPT I deficiency is wider than previously thought, causing specific neurologic dysfunction, mainly speech disorders at a large scale, that were unexpected in a fatty acid oxidation disorder. We suggest that early diagnosis and treatment is the key factor to prevent neurologic sequelae while an extensive neurological evaluation is essential in patients with CPT I deficiency both at the time of diagnosis and during the follow-up period.

Evaluation of the risk factors for noncommunicable diseases in patients with inborn errors of amino acid metabolism receiving nutrition therapy.

OBJECTIVES: There is growing concern about the low-protein and high-energy diet therapies used in the treatment of inherited amino acid metabolism disorders. We aimed to identify the risk factors for noncommunicable diseases that may arise from nutritional therapies and suggests approaches that may prevent the development of the noncommunicable diseases. METHODS: The present study evaluates 112 patients, on long-term nutritional therapy for at least the last 2 years with a diagnosis of an inborn error of the amino acid metabolism, and their 28 healthy siblings. The participants are assessed for the development of overweight and metabolic syndrome based on an analysis of anthropometric parameters, body composition and the results of biochemical tests. RESULTS: Anthropometric measurements including BMI, weight Z-score, waist circumference and fat mass were not significantly different between patients and controls. Height Z-scores were similar in phenylketonuria patients compared to controls, but lower in urea cycle disorders, organic acidemia and maple syrup urine disease groups. No increased risk of development of overweight or metabolic syndrome was detected in the patient group, while there were findings suggesting malnutrition in patients diagnosed with urea cycle disorders. There was a correlation between patients' BMI and C3-carnitine levels in organic acidemia patients and leucine levels in maple syrup urine disease patients. CONCLUSIONS: All forms of malnutrition can be prevented in patient groups receiving limited nutrients under a dietary management protocol, based on the findings of anthropometric and biochemical evaluations and analyses of body composition.

Novel GALT variations and genetic spectrum in Turkish population with the correlation of genotype and phenotype.

Classic galactosemia (OMIM#230400) is an autosomal recessive inborn error of carbohydrate metabolism caused by a deficiency of the galactose-1-phosphate-uridyl-transferase enzyme encoded by the GALT gene. Even though a galactose-restricted diet efficiently resolves the acute complications, it is insufficient to prevent long-term complications regarding speech defects, intellectual functioning, premature ovarian failure, cataract, hepatomegaly, dysarthria, ataxia, and tremor. Seventy-seven patients who were genetically diagnosed with classic galactosemia were included in this cohort. Identified novel variants were classified based on their predicted effect on the GALT function. Further, potential genotype-phenotype correlations were investigated via statistical analysis. In total, 18 different sequence variants were identified, including four novels (c.200delG/p.(Arg67Profs* 19), c.533T>G/ p.(Met178Arg), c.708_709delGT/p.(Ser236Argfs* 30), c.467C>A/p.(Ser156* )). Jaundice was the most common short-term finding with 80% (61/77). Even with early diagnosis, intellectual disability is encountered with 36% (27/74) of the long-term complications. Patients with biallelic missense variants have a significantly higher prevalence of cataracts (OR: 17.9). Longitudinal observations showed attenuation of cataracts and hepatomegaly. This study has shown the GALT variation spectrum of the Turkish population with a 30-year retrospective cohort, submitting a significant contribution to the genotype/phenotype correlation in galactosemia. This study also highlights the cost-effective importance of Sanger sequencing in the diagnosis of single-gene metabolic diseases.

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

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

Clinical and bi-genomic DNA findings of patients suspected to have mitochondrial diseases.

Background: Mitochondrial diseases are the most common group of inherited metabolic disorders, causing difficulties in definite diagnosis due to clinical and genetic heterogeneity. Clinical components are predominantly associated with pathogenic variants shown in nuclear or mitochondrial genomes that affect vital respiratory chain function. The development of high-throughput sequencing technologies has accelerated the elucidation of the genetic etiology of many genetic diseases that previously remained undiagnosed. Methods: Thirty affected patients from 24 unrelated families with clinical, radiological, biochemical, and histopathological evaluations considered for mitochondrial diseases were investigated. DNA isolated from the peripheral blood samples of probands was sequenced for nuclear exome and mitochondrial DNA (mtDNA) analyses. MtDNA sequencing was also performed from the muscle biopsy material in one patient. For segregation, Sanger sequencing is performed for pathogenic alterations in five other affected family members and healthy parents. Results: Exome sequencing revealed 14 different pathogenic variants in nine genes encoding mitochondrial function peptides (AARS2, EARS2, ECHS1, FBXL4, MICOS13, NDUFAF6, OXCT1, POLG, and TK2) in 12 patients from nine families and four variants in genes encoding important for muscle structure (CAPN3, DYSF, and TCAP) in six patients from four families. Three probands carried pathogenic mtDNA variations in two genes (MT-ATP6 and MT-TL1). Nine variants in five genes are reported for the first time with disease association: (AARS2: c.277C>T/p.(R93*), c.845C>G/p.(S282C); EARS2: c.319C>T/p.(R107C), c.1283delC/p.(P428Lfs*); ECHS1: c.161G>A/p.(R54His); c.202G>A/p.(E68Lys); NDUFAF6: c.479delA/p.(N162Ifs*27); and OXCT1: c.1370C>T/p.(T457I), c.1173-139G>T/p.(?). Conclusion: Bi-genomic DNA sequencing clarified genetic etiology in 67% (16/24) of the families. Diagnostic utility by mtDNA sequencing in 13% (3/24) and exome sequencing in 54% (13/24) of the families prioritized searching for nuclear genome pathologies for the first-tier test. Weakness and muscle wasting observed in 17% (4/24) of the families underlined that limb-girdle muscular dystrophy, similar to mitochondrial myopathy, is an essential point for differential diagnosis. The correct diagnosis is crucial for comprehensive genetic counseling of families. Also, it contributes to making treatment-helpful referrals, such as ensuring early access to medication for patients with mutations in the TK2 gene.

Triosephosphate Isomerase Deficiency: E105D Mutation in Unrelated Patients and Review of the Literature.

Introduction: Chronic haemolytic anaemia, increased susceptibility to infections, cardiomyopathy, neurodegeneration, and death in early childhood are the clinical findings of triosephosphate isomerase (TPI) deficiency, which is an ultra-rare disorder. The clinical and laboratory findings and the outcomes of 2 patients with TPI deficiency are reported, with a review of cases reported in the literature. Case Presentation: Two unrelated patients with haemolytic anaemia and neurologic findings who were diagnosed as having TPI deficiency are presented. Neonatal onset of initial symptoms was observed in both patients, and the age at diagnosis was around 2 years. The patients had increased susceptibility to infections and respiratory failure, but cardiac symptoms were not remarkable. Screening for inborn errors of metabolism revealed a previously unreported metabolic alteration determined using tandem mass spectrometry in acylcarnitine analysis, causing elevated propionyl carnitine levels in both patients. The patients had p.E105D (c.315G>C) homozygous mutations in the TPI1 gene. Although severely disabled, both patients are alive at the ages of 7 and 9 years. Discussion: For better management, it is important to investigate the genetic aetiology in patients with haemolytic anaemia with or without neurologic symptoms who do not have a definitive diagnosis. The differential diagnosis of elevated propionyl carnitine levels using tandem mass spectrometry screening should also include TPI deficiency.

Reanalysis of exome sequencing data reveals a treatable neurometabolic origin in two previously undiagnosed siblings with neurodevelopmental disorder.

Neurodevelopmental disorders (NDDs) have broad heterogeneity both clinically and genetically. Inborn errors of metabolism can be one of the reasons of neurodevelopmental disruption causing specific NDDs. Although there is tremendous advance in molecular identification via next-generation sequencing (NGS), there are still many unsolved patients with NDD. Reanalysis of NGS data with different pipelines can at least partially accomplish this challenge. Herein, we report clinic and genetic components of an adult sib-pair with an undiagnosed NDD condition, which has been solved through reanalysis of whole-exome sequencing (WES). Parallel analysis of SNP-based genotyping and WES was performed to focus on variants only in loci with positive logarithm of the odds scores. WES data was analyzed through three different pipelines with two distinct bed files. Reanalysis of WES data led us to detect a homozygous FOLR1 variant (ENST00000393676.5:c.610C > T, p.(Arg204Ter), rs952165627) in the affected sib-pair. Surprisingly, the variant could not be detected in the first analysis as the variant region is not included in the first bed file which may frequently be used. Biochemical tests of CSF have confirmed the genetic analysis, CSF folic acid levels were detected low in sib-pair, and intravenous folinic acid treatment improved the disease course for the first 6 months of follow-up even at late diagnosis age. Although combined analysis of SNP-based genotyping and WES is a powerful tool to reveal the genetic components of heterogeneous diseases, reanalysis of genome data still should be considered in unsolved patients. Also, biochemical screening helps us to decipher undiagnosed NDD that may be a treatable neurometabolic condition.

Leucine tolerance in children with MSUD is not correlated with plasma leucine levels at diagnosis.

OBJECTIVES: Maple syrup urine disease (MSUD) is an inborn metabolic disease. The nutritional treatment with restricted intake of branched chain amino acids and prevention of leucine toxicity are crucially important for a favorable outcome. The aim of this study is to analyze the relation of blood leucine levels at diagnosis with future leucine tolerances, to determine whether any prediction about the future leucine tolerances or plasma leucine levels is possible by evaluating blood leucine levels at diagnosis. METHODS: The study group consisted of 45 MSUD patients. Leucine levels at diagnosis were compared with age at diagnosis, leucine tolerances, maximum leucine levels/ages, and average blood leucine levels. RESULTS: The mean plasma leucine level at diagnosis was 2,355.47 ± 1,251.7 µmol/L (ref: 55-164 µmol/L). The median age at diagnosis was 17 days. Leucine tolerances per kg body weight declined until the age of 8 years and stabilized subsequently. The average age of maximum leucine level during follow-up was 3.14 ± 1.92 years, and the mean maximum lifetime plasma leucine level on follow-up was 1,452.13 ± 621.38 µmol/L. The leucine levels at diagnosis did not have any significant relationship with lifetime leucine tolerances, maximum plasma leucine levels or mean plasma leucine levels. CONCLUSIONS: The plasma leucine levels at diagnosis did not have a predictive value for later leucine tolerances or plasma leucine levels. The maximum lifetime leucine level is likely to happen within the first 3 years of life, underlining the importance of good metabolic control and compliance to dietary treatment at early ages.

Cardiologic evaluation of Turkish mitochondrial fatty acid oxidation disorders.

BACKGROUND: Mitochondrial fatty acid oxidation disorders (FAODs) cause impairment in energy metabolism and can lead to a spectrum of cardiac pathologies including cardiomyopathy and arrhythmias. The frequency of underlying cardiac pathologies and the response to recommended treatment in FAODs was investigated. METHODS: Sixty-eight children (35 males, 33 females) with the diagnosis of a FAOD were included in the study. Cardiac function was evaluated with 12-lead standard electrocardiography, echocardiography, and 24 h Holter monitoring. RESULTS: Forty-five patients (66%) were diagnosed after disease symptoms developed and 23 patients (34%) were diagnosed in the pre-symptomatic period. Among symptomatic patients (n: 45), cardiovascular findings were detected in 18 (40%) patients, including cardiomyopathy in 14 (31.1%) and conduction abnormalities in 4 (8.8%) patients. Cardiac symptoms were more frequently detected in primary systemic carnitine deficiency (57.1%). Patients with multiple acyl-CoA dehydrogenase, long-chain 3-hydroxyacyl-CoA dehydrogenase, and mitochondrial trifunctional protein deficiencies also had an increased frequency of cardiac symptoms. Patients with medium-chain acyl-CoA dehydrogenase, very long-chain acyl-CoA dehydrogenase, and carnitine palmitoyltransferase I deficiencies had a lower prevalence of cardiac symptoms both during admission and during clinical follow up. Cardiomyopathy resolved completely in 8/14 (57%) patients and partially in 2/14 (14.3%) patients with treatment. Two patients with cardiomyopathy died in the newborn period; cardiomyopathy persisted in 1 (7.1%) patient with very long-chain acyl-CoA dehydrogenase deficiency. CONCLUSION: Early diagnosis, treatment and follow up made a significant contribution to the improvement of cardiac symptoms of patients with FAODs.

A multinational study of acute and long-term outcomes of Type 1 galactosemia patients who carry the S135L (c.404C > T) variant of GALT.

Patients with galactosemia who carry the S135L (c.404C > T) variant of galactose-1-P uridylyltransferase (GALT), documented to encode low-level residual GALT activity, have been under-represented in most prior studies of outcomes in Type 1 galactosemia. What is known about the acute and long-term outcomes of these patients, therefore, is based on very limited data. Here, we present a study comparing acute and long-term outcomes of 12 patients homozygous for S135L, 25 patients compound heterozygous for S135L, and 105 patients homozygous for two GALT-null (G) alleles. This is the largest cohort of S135L patients characterized to date. Acute disease following milk exposure in the newborn period was common among patients in all 3 comparison groups in our study, as were long-term complications in the domains of speech, cognition, and motor outcomes. In contrast, while at least 80% of both GALT-null and S135L compound heterozygous girls and women showed evidence of an adverse ovarian outcome, prevalence was only 25% among S135L homozygotes. Further, all young women in this study with even one copy of S135L achieved spontaneous menarche; this is true for only about 33% of women with classic galactosemia. Overall, we observed that while most long-term outcomes trended milder among groups of patients with even one copy of S135L, many individual patients, either homozygous or compound heterozygous for S135L, nonetheless experienced long-term outcomes that were not mild. This was true despite detection by newborn screening and both early and life-long dietary restriction of galactose. This information should empower more evidence-based counseling for galactosemia patients with S135L.

The Use of Social Network in Daily Pediatric Practice and Education: Turkish Pediatric Atelier.

Using social media applications in pediatric education is not outdated, and its effectiveness has not been tested yet. For this reason, we shared the first results of the Pediatric Atelier experience that we realized through telegram application. We make an online survey to investigate the needs, requirements, pleasure, and suggestions of members through a web-based questionnaire. This cross-sectional survey study was delivered only to participants who were members of the workshop via their email addresses. Online questionnaires organized using Google Forms were sent to pediatric workshop members between March and June 2019. The questionnaire consisted of questions that measured the participants' basic demographic data, the use of the workshop, and the overall impact of the workshop on their professional behavior. While the institutions and positions of the participants were recorded, no other personal data (such as address and telephone) were collected. Among the 997 members, 417 (42%) of them answered the questionnaire. Respondents included 300 (72%) pediatrician, 21 (5%) pediatric subspeciality fellows, and 75 (18%) pediatric subspecialists. Of the 417 respondents, 217 (52%) were working in Istanbul, and 200 (48%) were working in other cities of Turkey. Among the responders, 233 (56%) were working in private hospitals or doctor offices. A total of 520 cases were consulted in 241 days of study period. Most consultations (n = 309, %59) were made from the Istanbul metropolitan area, and 203 (40%) consultations were from other cities of Turkey. The most frequently consulted departments were Pediatric infectious diseases: 166 (32%), Pediatric hematology and oncology: 56 (11%), and Neonatology: 43 (8%). Of the 520 consulted cases, 44 (8%) were related to life-threatening events, and 25 of them were hospitalized in the intensive care units, and 6 of them were required surgical operations. Of the 94% of responders thought this platform was useful and 82% of them stated that the case counseling part of the atelier was the most useful part. We think that the development of technology and artificial intelligence may lead to the usage of on-line platforms or systems in clinical medical practice. Clinical Trial Registration (if any). Registry name, registration number, web link to study on registry, and data sharing statement.

Clinical presentation and outcome in a series of 32 patients with 2-methylacetoacetyl-coenzyme A thiolase (MAT) deficiency.

2-methylacetoacetyl-coenzyme A thiolase (MAT) deficiency, also known as beta-ketothiolase deficiency, is an inborn error of ketone body utilization and isoleucine catabolism. It is caused by mutations in the ACAT1 gene and may present with metabolic ketoacidosis. In order to obtain a more comprehensive view on this disease, we have collected clinical and biochemical data as well as information on ACAT1 mutations of 32 patients from 12 metabolic centers in five countries. Patients were between 23months and 27years old, more than half of them were offspring of a consanguineous union. 63% of the study participants presented with a metabolic decompensation while most others were identified via newborn screening or family studies. In symptomatic patients, age at manifestation ranged between 5months and 6.8years. Only 7% developed a major mental disability while the vast majority was cognitively normal. More than one third of the identified mutations in ACAT1 are intronic mutations which are expected to disturb splicing. We identified several novel mutations but, in agreement with previous reports, no clear genotype-phenotype correlation could be found. Our study underlines that the prognosis in MAT deficiency is good and MAT deficient individuals may remain asymptomatic, if diagnosed early and preventive measures are applied.

3-Hydroxy-3-methylglutaryl-coenzyme A lyase deficiency: Clinical presentation and outcome in a series of 37 patients.

3-Hydroxy-3-methylglutaryl-coenzyme A lyase deficiency (HMGCLD) is a rare inborn error of ketone body synthesis and leucine degradation, caused by mutations in the HMGCL gene. In order to obtain a comprehensive view on this disease, we have collected clinical and biochemical data as well as information on HMGCL mutations of 37 patients (35 families) from metabolic centers in Belgium, Germany, The Netherlands, Switzerland, and Turkey. All patients were symptomatic at some stage with 94% presenting with an acute metabolic decompensation. In 50% of the patients, the disorder manifested neonatally, mostly within the first days of life. Only 8% of patients presented after one year of age. Six patients died prior to data collection. Long-term neurological complications were common. Half of the patients had a normal cognitive development while the remainder showed psychomotor deficits. We identified seven novel HMGCL mutations. In agreement with previous reports, no clear genotype-phenotype correlation could be found. This is the largest cohort of HMGCLD patients reported so far, demonstrating that HMGCLD is a potentially life-threatening disease with variable clinical outcome. Our findings suggest that the clinical course of HMGCLD cannot be predicted accurately from HMGCL genotype. The overall outcome in HMGCLD appears limited, thus rendering early diagnosis and strict avoidance of metabolic crises important.

Rapid Desensitization for Immediate Hypersensitivity to Galsulfase Therapy in Patients with MPS VI.

Mucopolysaccharidosis type VI (MPS VI) is a progressive, chronic, and multisystem lysosomal storage disease. Enzyme replacement therapy (ERT) with the recombinant human arylsulfatase B enzyme (galsulfase [Naglazyme]) is recommended as first-line therapy. It is generally reported as safe and well tolerated. Frequently observed mild to moderate infusion-related reactions which can be easily handled by reducing or interrupting the infusion and/or administering additional antihistamines, antipyretics, and corticosteroids are mostly mediated by non-IgE mechanisms. Here we report two children with MPS VI who experienced IgE-mediated reactions with galsulfase at the second year of the therapy. One child had anaphylaxis and the other had urticarial eruptions. They could receive ERT after successful rapid desensitization. To our knowledge, this is the second report on galsulfase allergy with IgE-mediated reaction. It is important to recognize IgE-mediated reactions since they can be life-threatening and do not respond to the standard therapies. We recommend allergy skin tests in the evaluation of infusion-related reactions unresponsive to standard therapies, so that continuation of ERT will be feasible after successful desensitization.