The PompeQoL questionnaire: Development and validation of a new measure for children and adolescents with Pompe disease.

Genetic disorders pose great challenges for affected individuals and their families, as they must cope with the irreversible nature of the disease and a life-long dependence on medical assistance and treatment. Children and adolescents dealing with Pompe disease (PD) often struggle to keep up with their peers in physical activities. To gain valuable insights into their subjective experiences and better understand their perception and coping related to daily challenges linked to their condition and treatment, the use of standardized questionnaires is crucial. This study introduces the novel PompeQoL 1.0 questionnaire for children and adolescents with PD, designed for comprehensive assessment of both disease-specific FDH and HRQoL through self- and proxy reports. Content validity was ensured through patients' and parents' involvement at the initial stages of development and in subsequent cognitive debriefing process. Participants found the questionnaire easy to understand, answerable, relevant, and comprehensive. Adjustments based on feedback from patients and their parents improved its utility as a patient- and observer-reported outcome measure. After careful item examination, 52 items were selected, demonstrating moderate to excellent test-retest reliability for most scales and initial evidence for satisfactory construct validity. The PompeQoL questionnaire stands as a valuable screening instrument for both clinical and research purposes. Future research should prioritize additional revisions and larger validation studies, focusing on testing the questionnaire in clinical practice and trials. Nevertheless, the PompeQoL 1.0 stands out as the first standardized measure providing insights into disease-specific FDH and HRQoL among children and adolescents with various forms of PD.

Poor adherence during adolescence is a risk factor for becoming lost-to-follow-up in patients with phenylketonuria.

Purpose: A high rate of lost to follow-up (LTFU) in patients with phenylketonuria (PKU) represents a main challenge. In this study, we investigated potential risk factors for becoming LTFU related to adolescence as a critical period of life. Methods: We retrospectively analyzed longitudinal data collected from 1993 to 2019 of patients diagnosed with classic PKU that were followed at our center during adolescence (14-18 y) and at least once in adulthood (>18 y). Patients who interrupted their contact with our center after the 18th birthday for at least 2 years were classified as LTFU. We performed a multivariate regression analysis to investigate following potential risk factors for becoming LTFU in adult life: sex, dietary compliance during adolescence assessed through the mean of the annual medians of phenylalanine plasma values, average number of contacts with the center during adolescence and age at first visit after the 18th birthday. Results: 93 patients (52 males, 41 females) were included in the study. 58% became LTFU during adulthood. The mean age at the last visit before becoming LTFU was 26.2 ± 5.1 years. In the multivariate Cox regression analysis we found that poor dietary compliance during adolescence was significantly associated with a higher risk of becoming LTFU during adulthood (p-value = 0.028). Discussion: Adult patients who displayed poor treatment adherence during adolescence should be identified and carefully monitored to prevent loss of contact.

Brain function in classic galactosemia, a galactosemia network (GalNet) members review.

Classic galactosemia (CG, OMIM #230400, ORPHA: 79,239) is a hereditary disorder of galactose metabolism that, despite treatment with galactose restriction, affects brain function in 85% of the patients. Problems with cognitive function, neuropsychological/social emotional difficulties, neurological symptoms, and abnormalities in neuroimaging and electrophysiological assessments are frequently reported in this group of patients, with an enormous individual variability. In this review, we describe the role of impaired galactose metabolism on brain dysfunction based on state of the art knowledge. Several proposed disease mechanisms are discussed, as well as the time of damage and potential treatment options. Furthermore, we combine data from longitudinal, cross-sectional and retrospective studies with the observations of specialist teams treating this disease to depict the brain disease course over time. Based on current data and insights, the majority of patients do not exhibit cognitive decline. A subset of patients, often with early onset cerebral and cerebellar volume loss, can nevertheless experience neurological worsening. While a large number of patients with CG suffer from anxiety and depression, the increased complaints about memory loss, anxiety and depression at an older age are likely multifactorial in origin.

Galactose epimerase deficiency: lessons from the GalNet registry.

BACKGROUND: Galactose epimerase (GALE) deficiency is a rare hereditary disorder of galactose metabolism with only a few cases described in the literature. This study aims to present the data of patients with GALE deficiency from different countries included through the Galactosemia Network to further expand the existing knowledge and review the current diagnostic strategy, treatment and follow-up of this not well characterized entity. METHODS: Observational study collecting medical data from December 2014 to April 2022 of 22 not previously reported patients from 14 centers in 9 countries. Patients were classified as generalized or non-generalized based on their genotype, enzyme activities in different tissues and/or clinical picture and professional judgment of the treating physician. RESULTS: In total 6 patients were classified as generalized and 16 as non-generalized. In the generalized group, acute neonatal illness was reported in 3, cognitive and developmental delays were present in 5 and hearing problems were reported in 3. Four generalized patients were homozygous for the genetic variant NM_001008216.2:c.280G > A (p.Val94Met). In the non-generalized group, no clearly related symptoms were found. Ten novel genetic variants were reported in this study population. CONCLUSION: The phenotypic spectrum of GALE deficiency ranges from asymptomatic to severe. The generalized patients have a phenotype that is in line with the 9 described cases in the literature and prescribing dietary interventions is the cornerstone for treatment. In the non-generalized group, treatment advice is more difficult. To be able to offer proper counseling, in addition to red blood cell enzyme activity, genetic studies, transferrin glycoform analysis and enzymatic measurements in fibroblasts are recommended. Due to lack of facilities, additional enzymatic testing is not common practice in many centers nor a tailored long-term follow-up is performed.

100 years of inherited metabolic disorders in Austria-A national registry of minimal birth prevalence, diagnosis, and clinical outcome of inborn errors of metabolism in Austria between 1921 and 2021.

Inherited metabolic disorders (IMDs) are a heterogeneous group of rare disorders characterized by disruption of metabolic pathways. To date, data on incidence and prevalence of IMDs are limited. Taking advantage of a functioning network within the Austrian metabolic group, our registry research aimed to update the data of the "Registry for Inherited Metabolic Disorders" started between 1985 and 1995 with retrospectively retrieved data on patients with IMDs according to the Society for the Study of Inborn Errors of Metabolism International Classification of Diseases 11 (SSIEM ICD11) catalogue. Included in this retrospective register were 2631 patients with an IMD according to the SSIEM ICD11 Classification, who were treated in Austria. Thus, a prevalence of 1.8/10 000 for 2020 and a median minimal birth prevalence of 16.9/100 000 (range 0.7/100 000-113/100 000) were calculated for the period 1921 to February 2021. We detected a male predominance (m:f = 1.2:1) and a mean age of currently alive patients of 17.6 years (range 5.16 months-100 years). Most common diagnoses were phenylketonuria (17.7%), classical galactosaemia (6.6%), and biotinidase deficiency (4.2%). The most common diagnosis categories were disorders of amino acid and peptide metabolism (819/2631; 31.1%), disorders of energy metabolism (396/2631; 15.1%), and lysosomal disorders (395/2631; 15.0%). In addition to its epidemiological relevance, the "Registry for Inherited Metabolic Disorders" is an important tool for enhancing an exchange between care providers. Moreover, by pooling expertise it prospectively improves patient treatment, similar to pediatric oncology protocols. A substantial requirement for ful filling this goal is to regularly update the registry and provide nationwide coverage with inclusion of all medical specialties.

A retrospective study on disease management in children and adolescents with phenylketonuria during the Covid-19 pandemic lockdown in Austria.

BACKGROUND: In classical phenylketonuria (PKU) phenylalanine (Phe) accumulates due to functional impairment of the enzyme phenylalanine hydroxylase caused by pathogenic variants in the PAH gene. PKU treatment prevents severe cognitive impairment. Blood Phe concentration is the main biochemical monitoring parameter. Between appointments and venous blood sampling, Austrian PKU patients send dried blood spots (DBS) for Phe measurements to their centre. Coronavirus disease-19 (COVID-19), caused by the SARS CoV-2 virus, was classified as a pandemic by the World Health Organization in March 2020. In Austria, two nationwide lockdowns were installed during the first and second pandemic wave with variable regional and national restrictions in between. This retrospective questionnaire study compared the frequency of Phe measurements and Phe concentrations during lockdown with the respective period of the previous year in children and adolescents with PKU and explored potential influencing factors. RESULTS: 77 patients (30 female, 47 male; mean age 12.4 [8-19] years in 2020) from five centres were included. The decline of venous samples taken on appointments in 2020 did not reach significance but the number of patients with none or only one DBS tripled from 4 (5.2%) in 2019 to 12 (15.6%) in 2020. Significantly more patients had a decline than a rise in the number of DBS sent in between 2019 and 2020 (p < 0.001; Chi2 = 14.79). Especially patients ≥ 16 years sent significantly less DBS in 2020 (T = 156, p = 0.02, r = 0.49). In patients who adhered to DBS measurements, Phe concentrations remained stable. Male or female sex and dietary only versus dietary plus sapropterin treatment did not influence frequency of measurements and median Phe. CONCLUSION: During the COVID pandemic, the number of PKU patients who stopped sending DBS to their metabolic centre increased significantly, especially among those older than 16 years. Those who kept up sending DBS maintained stable Phe concentrations. Our follow-up system, which is based on DBS sent in by patients to trigger communication with the metabolic team served adherent patients well. It failed, however, to actively retrieve patients who stopped or reduced Phe measurements.

Project "Backtoclinic I": An overview on the state of care of adult PKU patients in Austria.

BACKGROUND: High rates of lost to follow-up (LTFU) adult patients are a major concern in the long-term management of phenylketonuria (PKU). To address this issue, we designed the project "Backtoclinic" with the purpose of identifying LTFU adult PKU patients in Austria as a first step to reestablish appropriate treatment. SUBJECTS AND METHODS: Individuals born between 1966 and 1999 and diagnosed with PKU through the National Austrian Newborn Screening Program (NANSP) were identified using the NANSP's database. Follow-up data were collected in the Austrian metabolic centers (Medical University of Vienna, Graz, Innsbruck and Salzburg). Patients with no contact to any of these centers within the previous two years were classified as LTFU. Epidemiological characteristics of the whole study population as well as of LTFU- and currently in follow-up patients were analyzed. RESULTS: Between 1966 and 1999, 281 individuals were diagnosed with PKU through the NANSP. Two patients died in their first year of life and were excluded from the analysis. Of the remaining 279 patients (mean age ± SD: 36.7 ± 9.1 y, 42.7% females), 177 (63.4%) are currently LTFU. The rate of LTFU patients is higher in men than in women (68.1% vs 57.5%), and markedly increases with age in both sexes. The gender gap is greatest in young adults (52.6% vs. 25.0% in the age range 20.0-24.9 y) and declines with age (94.4% vs. 80.0% in the age range > 45.0 y). CONCLUSIONS: We found an alarming rate of 63.4% of LTFU adult PKU patients in Austria, and observed a gender gap in the PKU state of care. Our findings illustrate the urgent need for the metabolic community to identify LTFU adult PKU patients and to develop strategies to reestablish appropriate treatment for men and women with PKU.

Galactokinase deficiency: lessons from the GalNet registry.

PURPOSE: Galactokinase (GALK1) deficiency is a rare hereditary galactose metabolism disorder. Beyond cataract, the phenotypic spectrum is questionable. Data from affected patients included in the Galactosemias Network registry were collected to better characterize the phenotype. METHODS: Observational study collecting medical data of 53 not previously reported GALK1 deficient patients from 17 centers in 11 countries from December 2014 to April 2020. RESULTS: Neonatal or childhood cataract was reported in 15 and 4 patients respectively. The occurrence of neonatal hypoglycemia and infection were comparable with the general population, whereas bleeding diathesis (8.1% versus 2.17-5.9%) and encephalopathy (3.9% versus 0.3%) were reported more often. Elevated transaminases were seen in 25.5%. Cognitive delay was reported in 5 patients. Urinary galactitol was elevated in all patients at diagnosis; five showed unexpected Gal-1-P increase. Most patients showed enzyme activities ≤1%. Eleven different genotypes were described, including six unpublished variants. The majority was homozygous for NM_000154.1:c.82C>A (p.Pro28Thr). Thirty-five patients were diagnosed following newborn screening, which was clearly beneficial. CONCLUSION: The phenotype of GALK1 deficiency may include neonatal elevation of transaminases, bleeding diathesis, and encephalopathy in addition to cataract. Potential complications beyond the neonatal period are not systematically surveyed and a better delineation is needed.

Hepatorenal Tyrosinaemia: Impact of a Simplified Diet on Metabolic Control and Clinical Outcome.

Background: Tyrosinaemia type 1 is a rare inherited metabolic disease caused by an enzyme defect in the tyrosine degradation pathway. It is treated using nitisinone and a low-protein diet. In a workshop in 2013, a group of nutritional specialists from Germany, Switzerland and Austria agreed to advocate a simplified low-protein diet and to allow more natural protein intake in patients with tyrosinaemia type 1. This retrospective study evaluates the recommendations made at different treatment centers and their impact on clinical symptoms and metabolic control. Methods: For this multicenter study, questionnaires were sent to nine participating treatment centers to collect data on the general therapeutic approach and data of 47 individual patients treated by those centers. Results: Dietary simplification allocating food to 3 categories led to increased tyrosine and phenylalanine blood concentrations without weighing food. Phenylalanine levels were significantly higher in comparison to a strict dietary regimen whereas tyrosine levels in plasma did not change. Non-inferiority was shown for the simplification and liberalization of the diet. Compliance with dietary recommendations was higher using the simplified diet in comparison to the stricter approach. Age correlates negatively with compliance. Conclusions: Simplification of the diet with increased natural protein intake based on three categories of food may be implemented in the diet of patients with tyrosinaemia type 1 without significantly altering metabolic control. Patient compliance is strongly influencing tyrosine blood concentrations. A subsequent prospective study with a larger sample size is necessary to get a better insight into the effect of dietary recommendations on metabolic control.

Manifestations of neurological symptoms and thromboembolism in adults with MTHFR-deficiency.

BACKGROUND: Methylenetetrahydrofolate-reductase (MTHFR) deficiency is a rare autosomal recessive disorder affecting intracellular folate metabolism with affection of different organ systems and clinical manifestation usually in childhood. OBJECTIVE: We report on four adult members of a family with MTHFR deficiency presenting with neurological and thromboembolic complications in adulthood. METHODS: Extensive diagnostic work-up including genetic testing was performed in four adult members. RESULTS: The male siblings aged 42 and 32years presented with various neurological symptoms, and a recent history of deep vein thrombosis. Extensive diagnostic work-up revealed total homocysteine (tHcy) plasma concentrations of 135µmol/L and 231µmol/L. and compound heterozygosity for two novel MTHFR gene mutations in exon 2 (c.202C>G, p.Arg68Gly) and intron 10 (c.1632+2T>G), and the known polymorphic variant MTHFR c.665C>T (p.Ala222Val, MTHFR 677C>T). Their mother was heterozygous for MTHFR c.1632+2T>G and c.665C>T, and a paternal relative was heterozygous for MTHFR c.202.C>G and MTHFR c.665C>T mutation. Both brothers showed partial response to therapy with betaine and multivitamins with clinical improvement. MTHFR activity was determined in fibroblast extracts and was around 4% of the mean control. Cell culture analysis indicated a re-methylation defect due to MTHFR deficiency. CONCLUSION: Severe hyperhomocysteinemia due to two mutations of the MTHFR gene resulted in severe neurological symptoms in adulthood. Vitamin and methionine supplementation stabilize tHcy plasma levels. Severity of clinical manifestation varied greatly between the siblings. Damages to the nervous system may be present for years before becoming clinically manifest.

Demethylation of the promoter region of GPX3 in a newborn with classical phenylketonuria.

OBJECTIVES: Phenylketonuria (PKU) is characterized by a high phenylalanine (phe) in plasma and oxidative stress. However, the monitoring of oxidative stress in newborns with PKU using the activity levels of antioxidant enzymes is not optimal. We investigated the possibility of monitoring an increased reactive oxygen species (ROS) production using DNA methylation changes of an oxidative stress response element in the promoter region of an enzymatic antioxidant gene. DESIGN AND METHODS: Using DNA extracted from blood leukocytes, the cytosine phosphodiester bond guanine positions of an overlapping CCAAT box/metal response element (CGATTGGCTG) of the glutathione peroxidase 3 promoter activated by oxidative stimuli and expressed in plasma were analysed for methylation changes in 20 newborns with hyperphenylalaninemia and 20 healthy controls. RESULTS: A demethylated allele was detected in a PKU patient at a phe level of 465µmol/L on day 2 after birth, but not in other patients (phe<465µmol/L, ≥day 2 after birth; phe>465µmol/L, ≥day 3 after birth) and healthy controls (phe<465µmol/L, ≥day 2 after birth). CONCLUSIONS: The detection of the demethylated allele could be time and phe concentration dependent. The demethylated allele is suggested as an early epigenetic marker for an extracellular monitoring of an increased ROS production in newborns with PKU.

Riboflavin-Responsive and -Non-responsive Mutations in FAD Synthase Cause Multiple Acyl-CoA Dehydrogenase and Combined Respiratory-Chain Deficiency.

Multiple acyl-CoA dehydrogenase deficiencies (MADDs) are a heterogeneous group of metabolic disorders with combined respiratory-chain deficiency and a neuromuscular phenotype. Despite recent advances in understanding the genetic basis of MADD, a number of cases remain unexplained. Here, we report clinically relevant variants in FLAD1, which encodes FAD synthase (FADS), as the cause of MADD and respiratory-chain dysfunction in nine individuals recruited from metabolic centers in six countries. In most individuals, we identified biallelic frameshift variants in the molybdopterin binding (MPTb) domain, located upstream of the FADS domain. Inasmuch as FADS is essential for cellular supply of FAD cofactors, the finding of biallelic frameshift variants was unexpected. Using RNA sequencing analysis combined with protein mass spectrometry, we discovered FLAD1 isoforms, which only encode the FADS domain. The existence of these isoforms might explain why affected individuals with biallelic FLAD1 frameshift variants still harbor substantial FADS activity. Another group of individuals with a milder phenotype responsive to riboflavin were shown to have single amino acid changes in the FADS domain. When produced in E. coli, these mutant FADS proteins resulted in impaired but detectable FADS activity; for one of the variant proteins, the addition of FAD significantly improved protein stability, arguing for a chaperone-like action similar to what has been reported in other riboflavin-responsive inborn errors of metabolism. In conclusion, our studies identify FLAD1 variants as a cause of potentially treatable inborn errors of metabolism manifesting with MADD and shed light on the mechanisms by which FADS ensures cellular FAD homeostasis.

Clinical outcome, biochemical and therapeutic follow-up in 14 Austrian patients with Long-Chain 3-Hydroxy Acyl CoA Dehydrogenase Deficiency (LCHADD).

BACKGROUND: LCHADD is a long-fatty acid oxidation disorder with immediate symptoms and long-term complications. We evaluated data on clinical status, biochemical parameters, therapeutic regimens and outcome of Austrian LCHADD patients. STUDY DESIGN: Clinical and outcome data including history, diagnosis, short- and long-term manifestations, growth, psychomotor development, hospitalizations, therapy of 14 Austrian patients with LCHADD were evaluated. Biochemically, we evaluated creatine kinase (CK) and acyl carnitine profiles. RESULTS: All LCHADD patients are homozygous for the common mutation. Three are siblings. Diagnosis was first established biochemically. Nine/14 (64%) were prematures, with IRDS occurring in six. In nine (64%), diagnosis was established through newborn screening, the remaining five (36%) were diagnosed clinically. Four pregnancies were complicated by HELLP syndrome, one by preeclampsia. In two, intrauterine growth retardation and placental insufficiency were reported. Five were diagnosed with hepatopathy at some point, seven with cardiomyopathy and eight with retinopathy, clinically relevant only in one patient. Polyneuropathy is only present in one. Three patients have a PEG, one is regularly fed via NG-tube. Growth is normal in all, as well as psychomotor development, except for two extremely premature girls. In 11 patients, 165 episodes with elevated creatine kinase concentrations were observed with 6-31 (median 14) per patient; three have shown no elevated CK concentrations. Median total carnitine on therapy was 19 µmol/l (range 11-61). For 14 patients, there have been 181 hospitalizations (median 9 per patient), comprising 1337 in-patient-days. All centres adhere to treatment with a fat-defined diet; patients have between 15% and 40% of their energy intake from fat (median 29%), out of which between 20% and 80% are medium-chain triglycerides (MCT) (median 62%). Four patients have been treated with heptanoate (C7). CONCLUSION: Our data show LCHADD outcome can be favourable. Growth and psychomotor development is normal, except in two prematures. Frequency of CK measurements decreases with age, correlating with a decreasing number of hospitalizations. About 50% develop complications affecting different organ systems. There is no relevant difference between the patients treated in the respective centers. Concluding from single case reports, anaplerotic therapy with heptanoate should be further evaluated.

Cross-sectional observational study of 208 patients with non-classical urea cycle disorders.

Urea cycle disorders (UCDs) are inherited disorders of ammonia detoxification often regarded as mainly of relevance to pediatricians. Based on an increasing number of case studies it has become obvious that a significant number of UCD patients are affected by their disease in a non-classical way: presenting outside the newborn period, following a mild course, presenting with unusual clinical features, or asymptomatic patients with only biochemical signs of a UCD. These patients are surviving into adolescence and adulthood, rendering this group of diseases clinically relevant to adult physicians as well as pediatricians. In preparation for an international workshop we collected data on all patients with non-classical UCDs treated by the participants in 20 European metabolic centres. Information was collected on a cohort of 208 patients 50% of which were ≥ 16 years old. The largest subgroup (121 patients) had X-linked ornithine transcarbamylase deficiency (OTCD) of whom 83 were female and 29% of these were asymptomatic. In index patients, there was a mean delay from first symptoms to diagnosis of 1.6 years. Cognitive impairment was present in 36% of all patients including female OTCD patients (in 31%) and those 41 patients identified presymptomatically following positive newborn screening (in 12%). In conclusion, UCD patients with non-classical clinical presentations require the interest and care of adult physicians and have a high risk of neurological complications. To improve the outcome of UCDs, a greater awareness by health professionals of the importance of hyperammonemia and UCDs, and ultimately avoidance of the still long delay to correctly diagnose the patients, is crucial.

Understanding the role of argininosuccinate lyase transcript variants in the clinical and biochemical variability of the urea cycle disorder argininosuccinic aciduria.

Argininosuccinic aciduria (ASA) is an autosomal recessive urea cycle disorder caused by deficiency of argininosuccinate lyase (ASL) with a wide clinical spectrum from asymptomatic to severe hyperammonemic neonatal onset life-threatening courses. We investigated the role of ASL transcript variants in the clinical and biochemical variability of ASA. Recombinant proteins for ASL wild type, mutant p.E189G, and the frequently occurring transcript variants with exon 2 or 7 deletions were (co-)expressed in human embryonic kidney 293T cells. We found that exon 2-deleted ASL forms a stable truncated protein with no relevant activity but a dose-dependent dominant negative effect on enzymatic activity after co-expression with wild type or mutant ASL, whereas exon 7-deleted ASL is unstable but seems to have, nevertheless, a dominant negative effect on mutant ASL. These findings were supported by structural modeling predictions for ASL heterotetramer/homotetramer formation. Illustrating the physiological relevance, the predominant occurrence of exon 7-deleted ASL was found in two patients who were both heterozygous for the ASL mutant p.E189G. Our results suggest that ASL transcripts can contribute to the highly variable phenotype in ASA patients if expressed at high levels. Especially, the exon 2-deleted ASL variant may form a heterotetramer with wild type or mutant ASL, causing markedly reduced ASL activity.

Prevalence of tetrahydrobiopterine (BH4)-responsive alleles among Austrian patients with PAH deficiency: comprehensive results from molecular analysis in 147 patients.

Phenylketonuria (PKU, MIM 261600) is an autosomal recessive disorder caused by mutations of the phenylalanine hydroxylase gene (PAH, GenBank U49897.1, RefSeq NM_000277). To date more than 560 variants of the PAH gene have been identified. In Europe there is regional distribution of specific mutations. Due to recent progress in chaperone therapy, the prevalence of BH4-responsive alleles gained therapeutic importance. Here we report the mutational spectrum of PAH deficiency in 147 unrelated Austrian families. Overall mutation detection rate was 98.6 %. There was a total of 62 disease-causing mutations, including five novel mutations IVS4 + 6T>A, p.H290Y, IVS8-2A>G, p.A322V and p.I421S. The five most prevalent mutations found in patients were p.R408W, IVS12 + 1G>A, p.R261Q, p.R158Q and IVS2 + 5G>C. Neonatal phenylalanine levels before treatment were available in 114/147 patients. Prediction of BH4-responsiveness in patients with full genotypes was exclusively made according to published data. Among the 133 patients needing dietary treatment, 28.4 % are expected to be BH4 "non-responsive", 4.5 % are highly likely BH4-responsive, 35.8 % are probably BH4-responsive while no interpretation was possible for 31.3 %. The mutation data reflect the population history of Austria and provide information on the likely proportion of Austrian PKU patients that may benefit from BH4-therapy.

3-methylcrotonyl-CoA carboxylase deficiency: clinical, biochemical, enzymatic and molecular studies in 88 individuals.

BACKGROUND: Isolated 3-methylcrotonyl-CoA carboxylase (MCC) deficiency is an autosomal recessive disorder of leucine metabolism caused by mutations in MCCC1 or MCCC2 encoding the α and ß subunit of MCC, respectively. The phenotype is highly variable ranging from acute neonatal onset with fatal outcome to asymptomatic adults. METHODS: We report clinical, biochemical, enzymatic and mutation data of 88 MCC deficient individuals, 53 identified by newborn screening, 26 diagnosed due to clinical symptoms or positive family history and 9 mothers, identified following the positive newborn screening result of their baby. RESULTS: Fifty-seven percent of patients were asymptomatic while 43% showed clinical symptoms, many of which were probably not related to MCC deficiency but due to ascertainment bias. However, 12 patients (5 of 53 identified by newborn screening) presented with acute metabolic decompensations. We identified 15 novel MCCC1 and 16 novel MCCC2 mutant alleles. Additionally, we report expression studies on 3 MCCC1 and 8 MCCC2 mutations and show an overview of all 132 MCCC1 and MCCC2 variants known to date. CONCLUSIONS: Our data confirm that MCC deficiency, despite low penetrance, may lead to a severe clinical phenotype resembling classical organic acidurias. However, neither the genotype nor the biochemical phenotype is helpful in predicting the clinical course.

The national Austrian newborn screening program - eight years experience with mass spectrometry. past, present, and future goals.

BACKGROUND: the National Austrian Newborn Screening Program for inherited metabolic and endocrinologic disorders was introduced in 1966. The program continuously evolved by expanding the screening panel from phenylketonuria and galactosemia to congenital hypothyroidism, biotinidase deficiency, cystic fibrosis, and congenital adrenal hyperplasia. In 2002, the introduction of tandem mass spectrometry (MS/MS) substantially increased the number of detectable inborn errors of metabolism and now includes disorders of fatty acid oxidation, organic acidurias and various disorders of amino acid metabolism. OBJECTIVE: in this study we report our eight years experience with MS/MS in Austria and give an overview of the incidence of diseases, organization, updates on methods and current development and future aspects. METHODS: a total of 622,489 newborns were screened by MS/MS for more than 20 diseases in Austria between April 2002 and December 2009. Dried blood spot samples were collected and sent to the National Laboratory for Newborn Screening located at the Medical University of Vienna, Vienna, Austria. RESULTS: The resulting overall prevalence of inherited metabolic disorder identified by MS/MS was 1:2855, including 125 newborns with amino acidemias (1:4,980), 46 with organic acidurias (1:13,532), and 47 with fatty acid oxidation disorders (1:13,244). CONCLUSION: the introduction of MS/MS technology in Austria significantly increased the detection of inherited metabolic disorders that were previously not covered. A primary goal is the continuous effort by developing second-tier strategies with the inclusion of more specific markers in order to minimize the risk of false-negatives and to improve the positive predictive value of screening results. Early recognition of these disorders enables diagnosis and treatment before the onset of symptoms.

Total homocysteine, B-vitamins and genetic polymorphisms in patients with classical phenylketonuria.

Hyperhomocysteinemia has occasionally been reported in patients with phenylketonuria (PKU) and B-vitamin deficiency. In our study total homocysteine (tHcy) and B-vitamins were measured in treated PKU patients and healthy controls. In the patients, dietary parameters and genetic polymorphisms affecting the Hcy pathway were investigated to identify parameters modulating tHcy. A case control study including 37 PKU patients and 63 healthy controls was conducted. t-Tests for independent samples were used to test between groups. Multiple regressions with tHcy as dependent variable were calculated. Hardy-Weinberg expectations were tested against the observed distribution of genotypes applying the Chi-square goodness-of-fit method. THcy concentrations were not significantly different (p=0.059) while folate and cobalamin (Cbl) concentrations were significantly higher in PKU patients compared to controls. However, 29.7% of patients had tHcy concentrations >97th centile. THcy did not vary with age nor correlate with folate and Cbl concentrations probably due to high saturatory levels. The presence of genetic polymorphisms had no impact on tHcy. In conclusion, in PKU patients treated with amino acid mixtures enriched with B-vitamins, tHcy is not significantly higher than in healthy controls, but tHcy concentrations exceed the 97th centile in about one third of patients. Even higher B-vitamin saturation may be required to further decrease tHcy concentrations and factors generally influencing tHcy such as betaine are to be investigated in PKU patients in the future.

Transcultural pediatrics: compliance and outcome of phenylketonuria patients from families with an immigration background.

Living in a foreign country with a different lifestyle and a different orientation is a many-faceted challenge for immigrants. A considerable percentage (30-50%) of patients with metabolic disease come from immigrant families from Turkey and the Middle East. Phenylketonuria is one example of metabolic disease in which severe mental retardation can be entirely prevented by early detection via newborn screening and consistent dietary treatment. We report 7 phenylketonuria patients from 3 Turkish families who had considerable difficulty in coping with the diagnosis and adherence to the diet. Blood phenylalanine levels beyond recommended limits and IQ values below average, clearly demonstrate the risks arising from language as well as psychological and cultural communication barriers, despite standardized follow-up care structures and the observance of continuity by medical caregivers. To propose a basis for systematic improvement in the care of patients from immigrant families we suggest that a) the services of professional interpreters be used in case of language barriers; b) social workers with appropriate sociocultural and language competence should accompany the family in a professional manner; c) it would be meaningful to introduce treatment contracts that clearly establish the limits of the client's rights and duties as well as those of the care-givers. From the viewpoint of legislation, providing medical information is duty of the hospital and the use of translator is mandatory with patients from foreign countries and with foreign languages.