Prevalence of patients with lysosomal storage disorders and peroxisomal disorders: A nationwide survey in Japan.

INTRODUCTION: Lysosomal storage disorders and peroxisomal disorders are rare diseases caused by the accumulation of substrates of the metabolic pathway within lysosomes and peroxisomes, respectively. Owing to the rarity of these diseases, the prevalence of lysosomal storage disorders and peroxisomal disorders in Japan is unknown. Therefore, we conducted a nationwide survey to estimate the number of patients with lysosomal storage disorders and peroxisomal disorders in Japan. METHODS: A nationwide survey was conducted following the "Manual of nationwide epidemiological survey for understanding patient number and clinical epidemiology of rare diseases (3rd version)". A questionnaire asking for detailed information, such as disease phenotypes and medical history, was created and sent to 504 institutions with doctors who have experience in treating patients with lysosomal storage disorders and peroxisomal disorders. Result A total of 303 completed questionnaires were collected from 504 institutions (response rate: 60.1%). The number of patients was estimated by calculating the rate/frequency of overlap. The estimated number of patients was 1658 (±264.8) for Fabry disease, 72 (±11.3) for mucopolysaccharidosis I, 275 (±49.9) for mucopolysaccharidosis II, 211 (±31.3) for Gaucher disease, 124 (±25.8) for Pompe disease, 83 (±44.3) for metachromatic leukodystrophy, 57 (±9.4) for Niemann-Pick type C, and 262 (±42.3) for adrenoleukodystrophy. In addition the birth prevalence was calculated using the estimated number of patients and birth year data for each disease, and was 1.25 for Fabry disease, 0.09 for mucopolysaccharidosis I, 0.38 for mucopolysaccharidosis II, 0.19 for Gaucher disease, 0.14 for Pompe disease, 0.16 for metachromatic leukodystrophy, 0.16 for Niemann-Pick type C, and 0.20 for adrenoleukodystrophy. DISCUSSION: Among the diseases analyzed, the disease with the highest prevalence was Fabry disease, followed by mucopolysaccharidosis II, adrenoleukodystrophy, Gaucher disease and metachromatic leukodystrophy. In particular, the high prevalence of mucopolysaccharidosis II and Gaucher disease type II was a feature characteristic of Japan. CONCLUSION: We estimated the number of patients with lysosomal storage disorders and peroxisomal disorders in Japan. The details of the age at diagnosis and treatment methods for each disease were clarified, and will be useful for the early diagnosis of these patients and to provide appropriate treatments. Furthermore, our results suggest that supportive care and the development of an environment that can provide optimal medical care is important in the future.

Application of machine learning algorithms for the differential diagnosis of peroxisomal disorders.

We have established diagnostic thresholds of very long-chain fatty acids (VLCFA) for the differential diagnosis of peroxisomal disorders using the machine learning tools. The plasma samples of 131 controls and 90 cases were tested for VLCFA using gas chromatography-mass spectrometry following stable isotope dilution. These data were used to construct association rules and for recursive partitioning. The C26/22 in healthy controls ranged between 0.008 and 0.01. The C26 levels between 1.61 and 3.34 µmol/l and C26/C22 between 0.05 and 0.10 are diagnostic of X-linked adrenoleukodystrophy (X-ALD). Very high levels of C26 (>3.34 µmol/l) and C26/C22 ratio (>0.10) are diagnostic of Zellweger syndrome (ZS). Significant elevation of phytanic acid was observed in Refsum (t = 6.14, P < 0.0001) and Rhizomelic chondrodysplasia punctata (RCDP) (t = 16.72, P < 0.0001). The C26/C22 ratio is slightly elevated in RCDP (t = 2.58, P = 0.01) while no such elevation was observed in Refsum disease (t = 0.86, P = 0.39). The developed algorithm exhibited greater clinical utility (AUC: 0.99-1.00) in differentiating X-ALD, ZS and healthy controls. The algorithm has greater clinical utility in the differential diagnosis of peroxisomal disorders based on VLCFA pattern. Plasmalogens will add additional value in differentiating RCDP and Refsum disease.

Importancia de la semiología y la bioquímica en el abordaje diagnóstico de un trastorno de la biogénesis peroxisómica / The importance of semiology and biochemistry in the diagnostic management of a peroxisomal biogenesis disorder

Introducción. Los trastornos de la biogénesis de los peroxisomas se deben a mutaciones en los genes PEX, que codifican peroxinas requeridas para la biogénesis peroxisómica. Clínicamente se expresan como un espectro del síndrome de Zellweger, y hay una amplia variedad fenotípica. Su diagnóstico se realiza bioquímicamente y la confirmación es molecular. El objetivo de este caso ilustrativo es resaltar la importancia de la clínica y de las pruebas bioquímicas en el abordaje de una enfermedad peroxisómica. Caso clínico. Niño de 3 años con hipotonía neonatal, retraso global del desarrollo y fallo de medro, con un patrón en resonancia cerebral de leucodistrofia hipomielinizante, en quien se había sospechado un trastorno de la biogénesis de los peroxisomas por encontrarse una variante de significado incierto en PEX5, pero su clínica, los estudios bioquímicos y el análisis crítico de las pruebas moleculares hacían improbable este diagnóstico. Se hace énfasis en el abordaje que debería tenerse cuando se sospecha un trastorno del espectro del síndrome de Zellweger. Conclusión. En el caso descrito se sospechó un trastorno de la biogénesis de los peroxisomas por una secuenciación exómica que, al analizarse críticamente junto con la clínica y los hallazgos bioquímicos, hacía muy poco probable una enfermedad peroxisómica. Cuando se tiene sospecha clínica y por neuroimágenes, el abordaje diagnóstico principal debe partir del análisis bioquímico. Aunque la confirmación es molecular, estas pruebas deben interpretarse con precaución

Introduction. Peroxisomal biogenesis disorders are due to mutations in the PEX genes, which code for peroxins that are required for peroxisomal biogenesis. Clinically, they are expressed as a Zellweger syndrome spectrum, and there is a wide phenotypic variety. They are diagnosed biochemically, and confirmation is molecular. The aim of this illustrative case is to highlight the importance of the clinical features and biochemical testing in the management of a peroxisomal disease. Case report. A 3-year-old boy with neonatal hypotonia, overall developmental delay and failure to thrive and a pattern of hypomyelinating leukodystrophy in brain resonance. The suspected diagnosis was a disorder affecting the biogenesis of the peroxisomes due to having found a variant with an uncertain meaning in PEX5. The clinical features, the biochemical studies and critical analysis, however, made this diagnosis unlikely. Emphasis is placed on the management that must be applied when a Zellweger syndrome spectrum is suspected. Conclusion. In the case reported here, a peroxisomal biogenesis disorder was suspected owing to an exome sequencing which, on being critically analysed together with the clinical features and the biochemical findings, made a peroxisomal disease very unlikely. In cases of clinical suspicion, backed up by neuroimaging, the main diagnostic management must be based on the biochemistry analysis. Although confirmation is molecular, these tests must be interpreted with caution

A metabolomic map of Zellweger spectrum disorders reveals novel disease biomarkers.

PURPOSE: Peroxisome biogenesis disorders-Zellweger spectrum disorders (PBD-ZSD) are metabolic diseases with multisystem manifestations. Individuals with PBD-ZSD exhibit impaired peroxisomal biochemical functions and have abnormal levels of peroxisomal metabolites, but the broader metabolic impact of peroxisomal dysfunction and the utility of metabolomic methods is unknown. METHODS: We studied 19 individuals with clinically and molecularly characterized PBD-ZSD. We performed both quantitative peroxisomal biochemical diagnostic studies in parallel with untargeted small molecule metabolomic profiling in plasma samples with detection of >650 named compounds. RESULTS: The cohort represented intermediate to mild PBD-ZSD subjects with peroxisomal biochemical alterations on targeted analysis. Untargeted metabolomic profiling of these samples revealed elevations in pipecolic acid and long-chain lysophosphatidylcholines, as well as an unanticipated reduction in multiple sphingomyelin species. These sphingomyelin reductions observed were consistent across the PBD-ZSD samples and were rare in a population of >1,000 clinical samples. Interestingly, the pattern or "PBD-ZSD metabolome" was more pronounced in younger subjects suggesting studies earlier in life reveal larger biochemical changes. CONCLUSION: Untargeted metabolomics is effective in detecting mild to intermediate cases of PBD-ZSD. Surprisingly, dramatic reductions in plasma sphingomyelin are a consistent feature of the PBD-ZSD metabolome. The use of metabolomics in PBD-ZSD can provide insight into novel biomarkers of disease.

Plasma lipidomics as a diagnostic tool for peroxisomal disorders.

Peroxisomes are ubiquitous cell organelles that play an important role in lipid metabolism. Accordingly, peroxisomal disorders, including the peroxisome biogenesis disorders and peroxisomal single-enzyme deficiencies, are associated with aberrant lipid metabolism. Lipidomics is an emerging tool for diagnosis, disease-monitoring, identifying lipid biomarkers, and studying the underlying pathophysiology in disorders of lipid metabolism. In this study, we demonstrate the potential of lipidomics for the diagnosis of peroxisomal disorders using plasma samples from patients with different types of peroxisomal disorders. We show that the changes in the plasma profiles of phospholipids, di- and triglycerides, and cholesterol esters correspond with the characteristic metabolite abnormalities that are currently used in the metabolic screening for peroxisomal disorders. The lipidomics approach, however, gives a much more detailed overview of the metabolic changes that occur in the lipidome. Furthermore, we identified novel unique lipid species for specific peroxisomal diseases that are candidate biomarkers. The results presented in this paper show the power of lipidomics approaches to enable the specific diagnosis of different peroxisomal disorders.

Identification and diagnostic value of phytanoyl- and pristanoyl-carnitine in plasma from patients with peroxisomal disorders.

Phytanic acid is a branched-chain fatty acid, the level of which is elevated in patients with a variety of peroxisomal disorders, including Refsum disease, and Rhizomelic chondrodysplasia punctata type 1 and 5. Elevated levels of both phytanic and pristanic acid are found in patients with Zellweger Spectrum Disorders, and pristanic acid is elevated in patients with α-methylacyl-CoA racemase deficiency. For the diagnosis of peroxisomal disorders, a variety of metabolites can be measured in blood samples from suspected patients, including very long-chain fatty acids, phytanic and pristanic acid. Based on the fact that very long-chain fatty acylcarnitines are elevated in tissues and plasma from patients with certain peroxisomal disorders, we investigated whether phytanoyl- and pristanoyl-carnitine are also present in plasma from patients with different peroxisomal disorders. Our study shows that phytanoyl- and pristanoyl-carnitine are indeed present in plasma samples from patients with different types of peroxisomal disorders, but only when the total plasma levels of their corresponding fatty acids, phytanic acid and pristanic acid, are markedly elevated. We conclude that the measurement of phytanoyl- and pristanoyl-carnitine is not sensitive and specific enough to use these acylcarnitines as conclusive diagnostic markers for peroxisomal disorders.

Expanding the spectrum of PEX10-related peroxisomal biogenesis disorders: slowly progressive recessive ataxia.

Peroxisomal biogenesis disorders (PBDs) consist of a heterogeneous group of autosomal recessive diseases, in which peroxisome assembly and proliferation are impaired leading to severe multisystem disease and early death. PBDs include Zellweger spectrum disorders (ZSDs) with a relatively mild clinical phenotype caused by PEX1, (MIM# 602136), PEX2 (MIM# 170993), PEX6 (MIM# 601498), PEX10 (MIM# 602859), PEX12 (MIM# 601758), and PEX16 (MIM# 603360) mutations. Three adult patients are reported belonging to a non-consanguineous French family affected with slowly progressive cerebellar ataxia, axonal neuropathy, and pyramidal signs. Mental retardation and diabetes mellitus were optional. The age at onset was in childhood or in adolescence (3-15 years). Brain MRI showed marked cerebellar atrophy. Biochemical blood analyses suggested a mild peroxisomal defect. With whole exome sequencing, two mutations in PEX10 were found in the three patients: c.827G>T (novel) causing the missense change p.Cys276Phe and c.932G>A causing the missense change p.Arg311Gln. The phenotypic spectrum related to PEX10 mutations includes slowly progressive, syndromic recessive ataxia.

Clinical and Biochemical Pitfalls in the Diagnosis of Peroxisomal Disorders.

Peroxisomal disorders are a heterogeneous group of genetic metabolic disorders, caused by a defect in peroxisome biogenesis or a deficiency of a single peroxisomal enzyme. The peroxisomal disorders include the Zellweger spectrum disorders, the rhizomelic chondrodysplasia punctata spectrum disorders, X-linked adrenoleukodystrophy, and multiple single enzyme deficiencies. There are several core phenotypes caused by peroxisomal dysfunction that clinicians can recognize. The diagnosis is suggested by biochemical testing in blood and urine and confirmed by functional assays in cultured skin fibroblasts, followed by mutation analysis. This review describes the phenotype of the main peroxisomal disorders and possible pitfalls in (laboratory) diagnosis to aid clinicians in the recognition of this group of diseases.

The important role of biochemical and functional studies in the diagnostics of peroxisomal disorders.

Peroxisomes are dynamic organelles that play an essential role in a variety of metabolic pathways. Peroxisomal dysfunction can lead to various biochemical abnormalities and result in abnormal metabolite levels, such as increased very long-chain fatty acid or reduced plasmalogen levels. The metabolite abnormalities in peroxisomal disorders are used in the diagnostics of these disorders. In this paper we discuss in detail the different diagnostic tests available for peroxisomal disorders and focus specifically on the important role of biochemical and functional studies in cultured skin fibroblasts in reaching the right diagnosis. Several examples are shown to underline the power of such studies.

Effect of l-Arginine in One Patient with Peroxisome Biogenesis Disorder due to PEX12 Deficiency.

Peroxisome biogenesis disorders (PBD) are a heterogeneous group of disorders due to PEX genes mutations, with a broad clinical spectrum comprising severe neonatal disease to mild presentation. Recently, Berendse et al reported an improvement of peroxisomal functions with l-arginine supplementation in fibroblasts with specific mutations of PEX1, PEX6, and PEX12. We report the first treatment by l-arginine in a patient homozygous for the specific PEX12 mutation shown to be l-arginine responsive in fibroblasts. We described the effect of l-arginine on biochemical (decrease of some plasma peroxisomal parameters) and neurophysiological (improvement of deafness) parameters. Some subjective clinical effects have also been observed (no more sialorrhea, behavior improvement). More studies are needed to assess the efficacy of l-arginine in some PBD patients with specific mutations.

Determination of plasma pipecolic acid by an easy and rapid liquid chromatography-tandem mass spectrometry method.

Pipecolic acid (PA) is an important biochemical marker for the diagnosis of peroxisomal disorders. PA is also a factor responsible for hepatic encephalopathy and a possible biomarker for pyridoxine-dependent seizures. We developed an easy and rapid PA quantification method, by high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS), requiring no derivatization and applicable to small sample volumes. Plasma (100 µl) is extracted with 500 µl acetonitrile (ACN) containing 2 µmol/l [(2)H5]-phenylalanine as internal standard, vortexed and centrifuged. The supernatant is analyzed by HPLC-MS/MS in positive-ion mode using multiple reaction monitoring scan type. HPLC column is a Luna HILIC (150×3.0mm; 3 µ 200A): Buffer A: ammonium formate 5 mmol/l; Buffer B: ACN/H20 90:10 containing ammonium formate 5 mmol/l. PA retention time is 4.86 min. Recovery was 93.8%, linearity was assessed between 0.05 and 50 µmol/l (R(2)=0.998), lower limit of detection was 0.010 µmol/l and lower limit of quantification was 0.050 µmol/l. Coefficient of variation was 3.2% intra-assay and 3.4% inter-assay, respectively. Clinical validation was obtained by comparing PA plasma values from 5 patients affected by peroxisomal disorders (mean, 23.38 µmol/l; range, 11.20-37.1 µmol/l) to 24 ages related healthy subjects (mean, 1.711 µmol/l; range, 0.517-3.580 µmol/l).

Streamlined determination of lysophosphatidylcholines in dried blood spots for newborn screening of X-linked adrenoleukodystrophy.

BACKGROUND: Pre-symptomatic hematopoietic stem cell transplantation is essential to achieve best possible outcomes for patients with the childhood cerebral form of X-linked adrenoleukodystrophy (X-ALD). We describe a high-throughput method for measurement of C20-C26 lysophosphatidylcholines (LPCs) and biochemical diagnosis of X-ALD using the same dried blood spots (DBS) routinely used for newborn screening. METHODS: LPCs are extracted from 3-mm DBS punch with methanol containing an isotopically labeled LPC as internal standard. This extract is transferred to a 96-well plate, evaporated and then reconstituted in mobile phase for flow injection analysis tandem mass spectrometry (FIA-MS/MS) in selected reaction monitoring mode for measurement of four different LPCs (C20, C22, C24, C26) and the internal standard (d4-C26-LPC). Analysis time is 1.5min per sample. RESULTS: The mean CVs from the intra- and inter-assay experiments for LPCs were 6.3-15.1% for C20-LPC, 4.4-18.6% for C22-LPC and 4.5-14.3% for C24-LPC. Limits of detection were determined for C20-LPC (LOD=0.03µg/mL), C22-LPC (0.03µg/mL), C24-LPC (0.03µg/mL) and C26-LPC (0.01µg/mL). Reference ranges were established from DBS of 130 newborns and 20 adults. Samples of patients with X-ALD (n=16), peroxisomal biogenesis disorders (n=8), and X-ALD carriers (n=12) were analyzed blindly and all were correctly identified. CONCLUSION: Analysis of LPC species by FIA-MS/MS is a fast, simple and reliable method to screen for X-ALD and other peroxisomal disorders in DBS. To maximize specificity, abnormal results can be verified by a 2nd tier assay using LC-MS/MS.

Evidence of oxidative stress in peroxisomal disorders.

INTRODUCTION: Peroxisomal disorders are subdivided into peroxisome biogenesis disorders (PBDs) and single peroxisomal enzyme deficiency. Many peroxisomal diseases exhibit excessive oxidative stress, leading to neurological alterations and dysfunction. Peroxisomes use oxygen in oxidative reactions that generate hydrogen peroxide. This study aimed to investigate various oxidative stress parameters in patients suffering from peroxisomal disorders. METHODS: A total of 20 patients with peroxisomal disorders, aged six months to 13 years (mean age 5.9 ± 3.2 years), were compared to 14 healthy controls. All individuals were subjected to full history-taking, including a three-generation pedigree analysis concerning parental consanguinity and similarly affected members in the family, with meticulous clinical examination to detect any malformation or anomaly. Estimation of very-long-chain fatty acids and phytanic acid was done to verify the diagnosis. Brain magnetic resonance imaging, electroencephalogram, visual evoked potential, auditory potential and plain radiography were conducted to assess the pathological condition of the patients. Oxidative stress parameters, including nitric oxide (NO), malondialdehyde (MDA) and superoxide dismutase (SOD), were estimated in both the patients and controls. RESULTS: Significant increases in both MDA and NO were found in patients with PBDs. It was also demonstrated that SOD was significantly lower in patients with PDB than the controls. CONCLUSION: This study sheds more light on the link between oxidative stress and peroxisomal disorders, as oxidative stress may be a hallmark of peroxisomal disorders. Consequently, one of the useful neuronal rescue strategies could be treatment with antioxidant agents in addition to other lines of treatments.

Peanut consumption increases levels of plasma very long chain fatty acids in humans.

Peanut consumption has been suspected of raising plasma very long chain fatty acid (VLCFA) levels in humans. The effect of peanut consumption on VLCFAs was studied in six human subjects. After 3 to 4h of peanut butter ingestion, plasma C26:0 and C26:0/C22:0 were found to be significantly elevated to levels seen in patients with peroxisomal disorders. These levels returned to normal within 12h. Peanut consumption needs to be accounted for when interpreting VLCFAs.

Improved analysis of C26:0-lysophosphatidylcholine in dried-blood spots via negative ion mode HPLC-ESI-MS/MS for X-linked adrenoleukodystrophy newborn screening.

BACKGROUND: X-linked adrenoleukodystrophy (X-ALD) is the most common human peroxisomal disorder, and is caused by mutations in the peroxisomal transmembrane ALD protein (ALDP, ABCD1). The biochemical defect associated with X-ALD is an accumulation of very long-chain fatty acids (VLCFA, e.g. C24:0 and C26:0), which has been shown to result in the accumulation of C26:0-lysophosphatidylcholine (C26:0-LPC). METHODS: We describe the analysis of C26:0-LPC in dried-blood spots (DBS) using a rapid (30 min) and simple extraction procedure, isocratic HPLC resolution of LPC, and structure-specific analysis via negative ion mode tandem mass spectrometry. RESULTS: In putative normal DBS specimens from newborns (N=223) C26:0-LPC was 0.09±0.03 µmol/l whole blood, while in peroxisomal biogenesis disorder (including X-ALD) patients (N=28) C26:0-LPC was 1.13±0.67 µmol/l whole blood. Both multiple reaction monitoring and a neutral loss scan (225.1 Da) analysis of DBS were used to analyze LPC. CONCLUSIONS: Compared to a previous report of C26:0-LPC analysis in DBS, the method described here is simpler, faster, and more structure-specific for LPC with C26:0 acyl chains.

Peroxisomal biogenesis disorder biomarkers.

BACKGROUND: The pathological mechanisms underlying peroxisomal biogenesis disorders (PBD) are not fully understood and the available therapies are not sufficient. This stresses the importance of identifying biochemical markers that reflect the extent of peroxisomal dysfunction in plasma of PBD patients. METHODS: Very long chain fatty acids VLCFAs, Phytanic acid, inflammatory markers: tumor necrosis-alpha, interleukin-6, and interleukin-2 (TNF-alpha, IL-6, and IL-2), lipid peroxidation parameter malonedialdhyde (MDA), low density lipoprotein-cholesterol (LDL-C), high density lipoprotein-cholesterol (HDL-C), and catalase activity were measured. RESULTS: Significant increases in LDL-C, VLCFAs (C26:0, C26:0/C22:0 and C24:0/C22:0), Phytanic acid, MDA, and Catalase were observed along with significant decreases in Plasmalogen and HDL-C level. No significant difference could be found between male and female patients regarding the biochemical parameters. Both cholesterol and triglycerides showed no significant difference between patients and controls. The characteristic curve (ROC) showed that VLCFAs were the most significant diagnostic markers for PBD followed by TNF-alpha, IL2, IL6, MDA, and plasmalogens. CONCLUSIONS: PBD patients have impaired anti-oxidative defense together with increased inflammatory markers. We provide biomarkers that could guide therapies and prevention strategies. Based on our results we suggest clinical trials to investigate the role of dietary supplementation of antioxidants such as vitamin C and E as an adjuvant therapy for PBD patients.

Determination of pipecolic acid following trimethylsilyl and trifluoroacyl derivatisation on plasma filter paper by stable isotope GC-MS for peroxisomal disorders.

If early diagnosis is not made, patients with peroxisomal disorders rapidly progress to sudden death, physical defect or mental retardation resulted in storage of the toxic material into the brain. Therefore, it is necessary to develop the analytical method for rapid screening and/or correct confirmation diagnosis. The method utilizes [2H(9)]pipecolic acid as internal standard. The formation of trimethylsilyl derivative (TMS) of the carboxylic functional group was performed by adding MSTFA. And then 5 microL of methyl orange was added until the color of methyl orange was to yellow. Consecutively, the trifluoroacyl (TFA)-derivative of the -NH functional group was produced by adding MBTFA. GC-MS was set with specific ions (m/z 282, m/z 297) of the TMSTFA derivative of pipecolic acid for selected ion monitoring. The linearity of pipecolic acid in pooled plasma spots showed 0.9999 in the range of 10-150 ng investigated. The precision and accuracy was within S.D. of 5% (RSD, within 5%) for intra-day and inter-day assay. Normal control value has been determined in plasma spots of infant and adults aged 0-30 (including newborn). The utility of the method was demonstrated by quantifying various concentration of fortified pipecolic acid on a filter plasma spot. The new method was simple with just two step derivatisation, time and labor saving without SPE or liquid-liquid extraction, and convenience of delivery owing to the use of filter paper. The described method could be used for routine analysis, monitoring, and clinical diagnostic application of peroxisomal disorders on dietary therapy.

Rapid quantification of conjugated and unconjugated bile acids and C27 precursors in dried blood spots and small volumes of serum.

The aim of the study was to develop a method for fast and reliable diagnosis of peroxisomal diseases and to facilitate differential diagnosis of cholestatic hepatopathy. For the quantification of bile acids and their conjugates as well as C(27) precursors di- and trihydroxycholestanoic acid (DHCA, THCA), in small pediatric blood samples we combined HPLC separation on a reverse-phase C18 column with ESI-MS/MS analysis in the negative ion mode. Analysis was done with good precision (CV 3,7%-11.1%) and sufficient sensitivity (LOQ: 11-91 nmol/L) without derivatization. Complete analysis of 17 free and conjugated bile acids from dried blood spots and 10 microL serum samples, respectively, was performed within 12 min. Measurement of conjugated primary bile acids plus DHCA and THCA as well as ursodeoxycholic acid was done in 4.5 min. In blood spots of healthy newborns, conjugated primary bile acids were found in the range of 0.01 to 2.01 micromol/L. Concentrations of C(27) precursors were below the detection limit in normal controls. DHCA and THCA were specifically elevated in cases of peroxysomal defects and one Zellweger patient.

Plasmalogen levels in full-term neonates.

AIM: Plasmalogens are phospholipids characterized by the presence of a vinyl ether bond at the sn-1 position of the glycerol backbone. They are particularly abundant in the nervous system, the heart and striated muscle. Peroxisomes are essential for their biosynthesis and red blood cell (RBC) plasmalogen levels are a reliable test in the investigation of patients suspect for a peroxisomal defect. The functions attributed to them include protection against oxidative stress, myelin formation and signal transduction. The aim of the present study was the investigation of RBC plasmalogen levels in neonates. METHODS: A total of 25 healthy full-term, appropriate for gestational age neonates were studied. RBC plasmalogens were estimated using gas chromatography within the first five days of life. Fifteen healthy children 1-8-year olds served as controls. RESULTS: Statistically significant lower plasmalogen levels were found in neonates compared to older children. CONCLUSION: Our results indicate that a different range of normal values for plasmalogen levels should be used in the investigation of peroxisomal diseases in neonates. The lower levels of plasmalogens in neonates found in our study could render them more vulnerable to oxidative stress.