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Serum amyloid P component (SAP) and complement C1q are found highly co-localized with extracellular fibrillar amyloidbeta (Abeta) deposits in Alzheimer's disease (AD) brain. Conflicting data were reported earlier about the cerebrospinal fluid (CSF) levels of SAP and C1q in AD compared to controls. The objective of the present study was to compare the levels of Abeta(1-42), tau, C1q and SAP in CSF of a well characterized group of AD patients and controls, and to assess the association with dementia severity. Significantly decreased CSF levels of Abeta(1-42) were observed in the AD group (480 +/- 104 ng/L) as compared to controls (1,040 +/- 213 ng/L), whereas tau levels were significantly higher in patients with AD (618 +/- 292 ng/L) than in controls (277 +/- 136 ng/L). Combining the results of Abeta(1-42) and tau measurements resulted in a clear separation between the AD group and the controls. No significant differences in CSF levels of SAP and C1q were observed between the well characterized AD patients and non demented control group. Furthermore, we could not demonstrate a correlation between SAP and C1q CSF levels and the severity of the disease, expressed in Mini-Mental State Examination (MMSE) scores. Therefore, in our opinion these factors can be excluded from the list of potentially interesting biomarkers for AD diagnosis and progression.

Megalencephalic leukoencephalopathy with subcortical cysts (MLC) is an inherited neurologic disorder with macrocephaly before the age of one and slowly progressive deterioration of motor functions. Magnetic resonance imaging shows diffusely abnormal and swollen white matter of the cerebral hemispheres and the presence of subcortical cysts in the anterior-temporal region and often also in the frontoparietal region. Mutations in the MLC1 gene, encoding a putative membrane protein, have been recently identified as a cause for MLC. Here, we describe 14 new mutations in 18 patients. Two identified polymorphisms lead to alterations of amino acid residues. The role, suggested by others, of a mutation in the MLC1gene in catatonic schizophrenia and the possible function of the MLC1 protein as a cation channel are discussed.

Leukoencephalopathy with vanishing white matter is a recently defined autosomal recessive disorder. The course is chronic progressive with additional episodes of rapid deterioration, provoked by fever and minor head trauma. A previous study showed that mutations in the genes encoding the epsilon- or the beta-subunit of the eukaryotic translation initiation factor eIF2B, a complex consisting of five subunits, cause the disease in most patients. Seven unsolved patients remained. The unsolved patients were investigated by mutation analysis of the genes encoding the alpha-, gamma-, and delta-subunit of eIF2B and the gene encoding the alpha-subunit of eIF2, because phosphorylation of this latter subunit regulates eIF2B activity. Mutations were found in the genes encoding the alpha- (1 patient), gamma- (2 patients), and delta-subunits (2 patients) of eIF2B, but no mutations were found in the gene encoding the alpha-subunit of eIF2. In 2, both less typical patients, no mutations were found. Mutations in all five genes eIF2B subunit genes can cause VWM. eIF2B is essential for the initiation of translation of RNA into protein and is involved in regulation of the process, especially under circumstances of stress, such as fever. A defect in eIF2B may explain the sensitivity to stress factors in vanishing white matter patients.

Leukoencephalopathy with vanishing white matter (VWM) is an inherited brain disease that occurs mainly in children. The course is chronic-progressive with additional episodes of rapid deterioration following febrile infection or minor head trauma. We have identified mutations in EIF2B5 and EIF2B2, encoding the epsilon- and beta-subunits of the translation initiation factor eIF2B and located on chromosomes 3q27 and 14q24, respectively, as causing VWM. We found 16 different mutations in EIF2B5 in 29 patients from 23 families. We also found two distantly related individuals who were homozygous with respect to a missense mutation in EIF2B2, affecting a conserved amino acid. Three other patients also had mutations in EIF2B2. As eIF2B has an essential role in the regulation of translation under different conditions, including stress, this may explain the rapid deterioration of people with VWM under stress. Mutant translation initiation factors have not previously been implicated in disease.

Background: There is increasing evidence that oxidation of low-density lipoprotein (LDL) in the vascular wall plays an important role in the development of atherosclerosis. The present study was undertaken to characterise how different constituents of LDL contribute to its in vitro oxidisability., Methods: The LDL composition, i.e. lipids, antioxidants, fatty acids, plasmenylcholines, and baseline level of conjugated dienes (CD) of 94 well-controlled and normolipidaemic type 2 diabetic patients was measured. Two oxidisability indices were determined: the lag time, reflecting the resistance of LDL to copper-induced oxidation, and the amount of conjugated dienes formed during oxidation of LDL., Results: The lag time was not related to the total level of saturated, monounsaturated, and polyunsaturated fatty acids, but a strong inverse relationship was observed with fatty acids with three or more double bonds (r = -0.56, p < 0.001). In addition, an inverse relation was observed between the lag time and LDL-plasmenylcholine (r = -0.35, p < 0.001). Although not related to lag time in univariate analysis, alpha-tocopherol was a significant determinant in multiple regression analysis. A multiple linear regression model with LDL polyunsaturated fatty acids with three or more double bonds, alpha-tocopherol, monounsaturated fatty acids, and plasmenylcholines as determinants explained 47% of the variation in lag time. CD production was negatively correlated to oleic acid and positively to linoleic acid (r = -0.45 and r = 0.73, respectively; p<0.001)., Conclusions: Fatty acids with three or more double bonds were the most important predictor of LDL lag time, whereas oleic acid and linoleic acid were major determinants of the amount of CD formed during oxidation of LDL., (Copyright 2001 John Wiley & Sons, Ltd.)

Succinate semialdehyde dehydrogenase (ALDH5A1, encoding SSADH deficiency is a defect of 4-aminobutyric acid (GABA) degradation that manifests in humans as 4-hydroxybutyric (gamma-hydroxybutyric, GHB) aciduria. It is characterized by a non-specific neurological disorder including psychomotor retardation, language delay, seizures, hypotonia and ataxia. The current therapy, vigabatrin (VGB), is not uniformly successful. Here we report the development of Aldh5a1-deficient mice. At postnatal day 16-22 Aldh5a1-/- mice display ataxia and develop generalized seizures leading to rapid death. We observed increased amounts of GHB and total GABA in urine, brain and liver homogenates and detected significant gliosis in the hippocampus of Aldh5a1-/- mice. We found therapeutic intervention with phenobarbital or phenytoin ineffective, whereas intervention with vigabatrin or the GABAB receptor antagonist CGP 35348 (ref. 2) prevented tonic-clonic convulsions and significantly enhanced survival of the mutant mice. Because neurologic deterioration coincided with weaning, we hypothesized the presence of a protective compound in breast milk. Indeed, treatment of mutant mice with the amino acid taurine rescued Aldh5a1-/- mice. These findings provide insight into pathomechanisms and may have therapeutic relevance for the human SSADH deficiency disease and GHB overdose and toxicity.

Objective: Previous studies have shown decreased levels of placenta growth factor in serum of pregnant women with preeclampsia. The aim of this study was to investigate whether levels of placenta growth factor are decreased before the clinical onset of preeclampsia, and whether placenta growth factor levels are decreased in pregnancies complicated by intrauterine growth restriction., Methods: From an ongoing longitudinal study, 101 plasma samples were collected from 72 pregnant women at weeks 11-21 of gestation. Placenta growth factor levels were determined retrospectively in plasma using an enzyme-linked immunosorbent assay. Correlations between plasma concentrations of placenta growth factor and pregnancy outcome were evaluated., Results: Plasma samples of 72 patients were analyzed. Forty-four patients had no pregnancy complications, 18 developed preeclampsia, and 10 women had pregnancies complicated by intrauterine growth restriction. Between week 17 and week 21 of pregnancy, a significantly lower level of placenta growth factor was found in plasma of patients who later developed preeclampsia (n = 10), compared with control pregnancies (n = 25, P = .004). In women with a growth-restricted baby at birth (n = 5), levels of placenta growth factor were also low., Conclusions: Our results show that plasma placenta growth factor levels are decreased before preeclampsia is clinically evident. The data suggest that placenta growth factor may be useful to determine the relative risk of developing preeclampsia and intrauterine growth restriction.

Megalencephalic leukoencephalopathy with subcortical cysts (MLC) is an autosomal recessive disorder characterized by macrocephaly, deterioration of motor functions with ataxia, and spasticity, eventuating in mental decline. The brain appears swollen on magnetic resonance imaging, with diffuse white-matter abnormalities and the invariable presence of subcortical cysts. MLC was recently localized on chromosome 22q(tel). We have narrowed down the critical region by linkage analysis of 11 informative families with MLC to a region of approximately 250 kb, containing four known genes. One family with two patients who were siblings did not display linkage between the MLC phenotype and any of the analyzed microsatellite markers on chromosome 22q(tel), suggesting genetic heterogeneity and the existence of at least a second MLC locus. The maximum two-point LOD score for the 11 families was 6.6 at recombination fraction .02. Twelve different mutations in seven informative and six uninformative families were found in one of the candidate genes, KIAA0027, which we renamed "MLC1." The gene encodes a putative membrane protein with eight predicted transmembrane domains. The patients of one family were compound heterozygotes for mutations that both introduced stop codons. The mutations further included frameshifts, splice-acceptor mutations, a putative splice-donor mutation, and amino acid substitutions of residues in predicted transmembrane domains. These data provide strong evidence that mutations of MLC1 cause the disease.

Inherited succinic semialdehyde dehydrogenase (SSADH; EC1.2.1.24; McKusick 271980) deficiency is a defect of GABA degradation which leads to accumulation of 4-hydroxybutyric acid (gamma-hydroxybutyric acid; GHB) in physiologic fluids of patients. Prenatal diagnosis (PND) was performed in three at-risk pregnancies employing combinations of: (1) reverse-transcription-polymerase chain reaction (RT-PCR) and genomic DNA amplification followed by sequencing using isolated leukocytes or cultured human lymphoblasts; (2) GHB quantitation in amniotic fluid; or (3) SSADH enzyme assay in chorionic villus (CV) and/or amniocytes. In two pregnancies, all analyses were concordant for prediction of disease status in the fetus. In the third case, enzyme activity in CV (deficient) and metabolite analysis in amniotic fluid (normal) were discordant. For clarification, mutation analysis was undertaken in CV, confirming heterozygosity for the mutation previously identified in the proband. We hypothesize that delayed transit time for shipment of CV between Greece and the United States (8 days) led to enhanced degradation of heterozygous SSADH enzyme activity. Our data demonstrate the importance of combined metabolite, enzyme, and DNA analysis for increased accuracy in the PND of SSADH deficiency., (Copyright 2001 Academic Press.)

An 4-mo-old male was found to have an isolated increase in 2-methylbutyrylglycine (2-MBG) and 2-methylbutyrylcamitine (2-MBC) in physiologic fluids. In vitro oxidation studies in cultured fibroblasts using 13C- and 14C-labeled branched chain amino acids indicated an isolated block in 2-methylbutyryl-CoA dehydrogenase (2-MBCDase). Western blotting revealed absence of 2-MBCDase protein in fibroblast extracts; DNA sequencing identified a single 778 C>T substitution in the 2-MBCDase coding region (778 C>T), substituting phenylalanine for leucine at amino acid 222 (L222F) and absence of enzyme activity for the 2-MBCDase protein expressed in Escherichia coli. Prenatal diagnosis in a subsequent pregnancy suggested an affected female fetus, supporting an autosomal recessive mode of inheritance. These data confirm the first documented case of isolated 2-MBCDase deficiency in humans.

Leukoencephalopathy with vanishing white matter (VWM) is an autosomal recessive disorder with normal early development and, usually, childhood-onset neurological deterioration. At present, diagnosis of VWM is based on clinical examination and the results of repeat magnetic resonance imaging and magnetic resonance spectroscopy, which show that, with time, increasing amounts of the cerebral white matter vanish and are replaced by cerebrospinal fluid. We have performed a genome linkage screening of a panel of 19 families of different ethnic origins. Significant linkage to chromosome 3q27 was observed in a 7-cM interval between markers D3S3730 and D3S3592, with a maximum multipoint LOD score of 5.1 calculated from the entire data set. The results of genealogical studies have suggested that seven parents in four Dutch families with VWM may have inherited an allele for the disease from a common ancestor who lived at least eight generations ago. Analysis of these families provided further evidence for the localization of the gene for VWM to 3q27. The patients shared a haplotype spanning 5 cM between markers D3S1618 and D3S3592. In one family of a different ethnic background, the patient had, in the same region, homozygosity for 13 consecutive markers spanning at least 12 cM, suggesting consanguinity between the parents. A healthy sibling of this patient had the same homozygous haplotype, which suggests that the healthy sibling is presymptomatic for the disease.

We present two patients with a suspected inborn error of metabolism. A female newborn presented with dysmorphic features and convulsions. Metabolic screening suggested a defect in isoleucine degradation. Within 2 weeks after the introduction of an isoleucine-restricted diet, she developed a severe acrodermatitis enteropathica-like syndrome. The plasma level of isoleucine was low with a normal leucine/isoleucine ratio. The second patient, a female infant deficient in leucine as a result of a leucine-restricted diet, did not develop a dermatosis. Isoleucine is essential for normal growth and differentiation of keratinocytes and enterocytes. Deficiency of isoleucine, and not leucine or an imbalance in the leucine/isoleucine ratio, may result in an acrodermatitis enteropathica-like syndrome.

X-linked adrenoleukodystrophy (X-ALD) is an inherited disorder of peroxisomal beta-oxidation, which results in accumulation of very long-chain fatty acids, causing damage to the nervous system, adrenal cortex and testis. The two most frequent phenotypes are childhood cerebral adrenoleukodystrophy (CCALD) and adrenomyeloneuropathy (AMN). Some affected males demonstrate no clinical signs (asymptomatic ALD), whereas female carriers can also be affected. Patients with X-ALD have been treated with Lorenzo's oil, a 4:1 combination of oleic acid and erucic acid, with thrombocytopenia as the main side effect and sometimes leading to a hemorrhagic diathesis. We studied platelet count, size and membrane surface exposure of platelet activation antigens in 17 adult X-ALD patients. Eight patients used the prescribed amount of erucic acid (as glyceroltrierucate) or more (very compliant), five used less(compliant), and four did not use the diet. All eight very compliant patients had highly enlarged platelets and seven manifested thrombocytopenia. An enhanced in vivo platelet activation status was established by increased platelet surface expression of P-selectin (CD62P, PADGEM, GMP-140) in five of the seven thrombocytopenic patients, and of increased fibrinogen receptor exposure (measured with the antibody PAC-1) in three of these five patients. The other nine compliant or untreated patients had normal platelet counts and, generally, normal P-selection and fibrinogen receptor expression. A diet-induced 7- to 27-fold enrichment of erucic acid was observed in the platelets of the four patients studied. We conclude that the thrombocytopenia in AMN patients using Lorenzo'soil is associated with circulating platelets that have an increased erucic acid content, size and activation status. We hypothesize that the erucic acid in some way induces the increased size and thus, directly or indirectly, increased platelet activation or instability in vivo. This then causes the thrombocytopenia, with circulating platelets representing a population that has not yet been sufficiently changed to be removed, but has clear signs of activation.

This first detailed report of a female patient with functional methionine synthase deficiency due to the cblE defect describes treatment with several vitamins and cofactors and clinical progress for 17 years. Before treatment, major findings were microcephaly, psychomotor retardation, episodic reduced consciousness, megaloblastic anaemia, increased plasma free homocystine (> 20 mumol/L), low plasma methionine (< 10 mumol/L) and increased excretion of formiminoglutamate. On high-dose folic acid, biochemical abnormalities such as formiminoglutamate excretion and homocystinuria nearly normalized, but clinical and haematological abnormalities remained. On replacement of folate with methylcobalamin, alertness, motor function, speech and the electroencephalogram improved, biochemical features were similar, but the mean corpuscular volume increased. The best control was observed on a combination of folate and methylcobalamin. At 17 years of age she remains severely mentally retarded. In cultured fibroblasts methionine synthesis was reduced (0.03 nmol/mg/per 16 h, controls 2.4-6.9); methionine synthase activity was normal under high reducing conditions but decreased on limiting the reducing agent, dithiothreitol, to 5 mmol/L (18% of total, controls 51-81%); formation of methylcobalamin was low (4.5% of total cobalamins, control 57.5%) and complementation studies indicated the cblE defect. Methionine formation showed only minor increases in cells grown in folate- or cobalamin-supplemented medium. Serine synthesis, which was low in normal medium, increased with cobalamin supplementation. These studies suggest further heterogeneity within cblE mutants, show the difficulty of establishing the enzyme defect in vitro, and indicate a role for folate in addition to cobalamin in treatment.

Twin brothers were born with clinical symptoms indicating that they were suffering from Zellweger syndrome. However, instead of a generalized peroxisomal dysfunction, only very long-chain fatty acids and the pristanic acid/phytanic acid ratio were elevated in plasma and decreased oxidation of very long-chain fatty acids and pristanic acid was the only impairment found in fibroblasts. The other peroxisomal parameters tested were normal, including normal oxidation of phytanic acid and normal activity of dihydroxyacetonephosphate acyltransferase in fibroblasts as well as normal plasma bile acids. Although the biochemical results point to a defect in peroxisomal beta-oxidation, the isolated finding of impaired oxidation of very long-chain fatty acids and pristanic acid has to our knowledge not been reported previously and is difficult to explain by a deficiency of a known peroxisomal beta-oxidation enzyme.

The Smith-Lemli-Opitz syndrome is a genetic disorder characterized by typical clinical features including reduced myelination of both brain and peripheral nervous system and defective cholesterol biosynthesis. In patients this results in very low cholesterol concentrations and accumulation of cholesterol precursors in plasma, tissues, cultured cells and faeces. We now show that the cholesterol concentration in CSF of Smith-Lemli-Opitz patients is markedly decreased and that 7- and 8-dehydrocholesterol concentrations are highly increased in comparison to controls. Moreover, dietary treatment of patients with cholesterol seems not to affect CSF cholesterol concentration.

The Museum Vrolik collection of human anatomy comprises 360 recently re-described specimens with congenital anomalies. The external findings in one of these specimens, originally described by Willem Vrolik (1801-1863) 130 years ago, were suggestive of Smith-Lemli-Opitz (SLO) syndrome. Cholesterol synthesis was analyzed in skin biopsies, obtained from the suspected SLO specimen and a control specimen. The cholesterol levels in the SLO specimen and in the control specimen were in the proportion of 1 to 45. This confirms the diagnosis in this specimen which, to our knowledge, represents the oldest known case of SLO syndrome.

In recent years an increasing number of inherited diseases in man have been identified in which there is an impairment in one or more peroxisomal functions. This paper discusses the current state of knowledge on these disorders with particular emphasis on the metabolic abnormalities in these diseases.

Unlabelled: Rhizomelic chondrodysplasia punctata (RCDP) is clinically characterized by symmetrical shortening of the proximal limbs, contractures of joints, a characteristic dysmorphic face, and cataracts. In the classical form an impairment of several peroxisomal functions and enzymes (plasmalogen synthesis, phytanic acid oxidation, 3-oxoacyl-CoA thiolase) has been repeatedly shown. Recently a variant involving only the peroxisomal dihydroxyacetonephosphate acyltransferase (DHAP-AT) has been described. We present a patient with isolated DHAP-AT deficiency and all clinical, radiological and pathological features of classical RCDP. For the first time, microscopy and immunocytochemistry of hepatocytes could be performed., Conclusion: In contrast to studies on classical rhizomelic chondrodysplasia punctata which have shown enlarged peroxisomes in numbers varying from hepatocyte to hepatocyte, the peroxisomes in our patient seem to be normal in size, number and shape.

We report three cases of L-2-hydroxyglutaric acidemia and three cases of Canavan disease. The L-2-hydroxyglutaric acidemia cases are the first biochemically proven Turkish cases. Magnetic resonance imaging findings in the cases and similarities between the two diseases are emphasized. Both diseases are characterized by predominant subcortical white-matter involvement and dentate nuclei lesions with variable basal ganglia involvement. Canavan disease differs from L-2-hydroxyglutaric acidemia by the presence of typical brainstem involvement.

Canavan disease is inherited as an autosomal recessive trait that is caused by the deficiency of aspartoacylase (ASPA). The majority of patients with Canavan disease are from an Ashkenazi Jewish background. Mutations in ASPA that lead to loss of enzymatic activity have been identified, and E285A and Y231X are the two predominant mutations that account for 97% of the mutant chromosomes in Ashkenazi Jewish patients. The current study was aimed at finding the molecular basis of Canavan disease in 25 independent patients of non-Jewish background. Eight novel and three previously characterized mutations accounted for 80% (40/50) of mutant chromosomes. The A305E missense mutation accounted for 48% (24/50) of mutant chromosomes in patients of western European descent, while the two predominant Jewish mutations each accounted for a single mutant chromosome. The eight novel mutations identified included 1- and 4-bp deletions (32 deltaT and 876 deltaAGAA, respectively) and I16T, G27R, D114E, G123E, C152Y, and R168C missense mutations. The homozygous 32 deltaT deletion was identified in the only known patient of African-American origin with Canavan disease. The heterozygosity for 876 deltaAGAA mutation was identified in three independent patients from England. Six single-base changes leading to missense mutations were identified in patients from Turkey (D114E, R168C), The Netherlands (I16T), Germany (G27R), Ireland (C152Y), and Canada (G123E). A PCR-based protocol is described that was used to introduce mutations in wild-type cDNA. In vitro expression of mutant cDNA clones demonstrated that all of these mutations led to a deficiency of ASPA and should therefore result in Canavan disease.

Rhizomelic chondrodysplasia calcificans punctata (RCDP) is an autosomal recessive peroxisomal disorder which affects phytanic acid oxidation and de novo biosynthesis of plasmalogens in liver and fibroblasts. Peroxisomal thiolase is present in its unprocessed precursor form (44 kDa). We studied a mentally retarded 9-year-old girl with cataracts and atypical bone dysplasia. Neurological findings were mild compared to classic RCDP. Plasma phytanic acid was normal. Results of de novo plasmalogen synthesis and phytanic acid oxidation studied in cultured skin fibroblasts were intermediate between normal controls and classic RCDP. Peroxisomal thiolase was present only as the unprocessed 44 kDa protein. Taken together these results suggest that we are dealing with a variant form of RCDP with clinical and biochemical abnormalities much milder as compared to classic RCDP. In order to establish the genetic relationship between our patient and classic RCDP patients complementation studies were carried out. Earlier studies had already shown that fibroblasts from all RCDP patients studied belong to a single complementation group. Fibroblasts from our patient could also be assigned to this complementation group suggesting that the phenotypic variability results from different mutations within the same gene.

The peroxisomal disorders represent a group of inherited diseases in man in which there is an impairment in one or more peroxisomal functions. The disorders known up to now are usually subdivided into three groups depending upon whether there is a more generalized, multiple or single loss of peroxisomal functions. In this paper we will briefly describe the peroxisomal disorders known thus far with the biochemical abnormalities identified. Furthermore, we will describe a straightforward approach for the postnatal identification of patients suspected to suffer from a peroxisomal disorder which is of great importance since reliable prenatal diagnostic methods have become available for each of these disorders.

Peroxisomal deficiency disorders, which are genetically transmitted, are assumed to be expressed in all cells, and the use of cultured skin fibroblasts for diagnosis and research is based on this assumption. We describe three patients with clinical, biochemical, and microscopic evidence of a peroxisomal disorder. However, their liver displays mosaicism, i.e., parenchymal cells with peroxisomes are adjacent to cells without peroxisomes. Ten percent (volume), 8%, and less than 1% of the parenchyma possessed peroxisomes that can be identified in immunocytochemical tests for six matrix and membrane proteins performed by light and electron microscopy. In the bulk of the parenchyma, catalase is localized in the cytoplasm, and in such cells no peroxisomes are evident by electron microscopy and immunolabeling for the 43-kd peroxisomal membrane protein (PMP) in two patients; in the third case, peroxisomal membrane ghosts are present. Immunoblots of peroxisomal beta-oxidation enzymes show a pattern similar to that from patients with a generalized peroxisomal deficiency. In contrast to the clinical and biochemical signs of peroxisomal dysfunction and hepatic histopathology, cultured fibroblasts from two patients demonstrate normal peroxisomal functions, including very-long-chain fatty acid oxidation and plasmalogen synthesis.

A case is reported of a male fetus at risk of X-linked adrenoleucodystrophy who showed a normal cultured chorionic villus cell very long chain fatty acid (VLCFA) profile but at birth exhibited grossly abnormal plasma and cultured fibroblast VLCFAs. Maternal contamination or a sample mix-up was excluded by chromosome analysis and analysis of polymorphic markers. This is the second report of a fetus affected with this disorder who showed normal cultured chorionic villus cell VLCFAs. It highlights the importance of a proper audit of all prenatal diagnoses to evaluate method reliability.

One of the main functions of mammalian peroxisomes is the beta-oxidation of a variety of fatty acids and fatty acid derivatives, including very long-chain fatty acids. Oxidation of these fatty acids is deficient in a number of different peroxisomal disorders, including the disorders of peroxisome biogenesis (Zellweger syndrome, neonatal adrenoleukodystrophy and infantile Refsum disease), X-linked adrenoleukodystrophy and a number of other disorders of peroxisomal beta-oxidation of known and unknown aetiology. Accurate measurement of peroxisomal fatty acid oxidation is of utmost importance for correct postnatal and prenatal diagnosis of these disorders. In this paper we describe a straightforward and accurate assay method to measure the beta-oxidation of palmitic acid (C16:0), hexacosanoic acid (C26:0) and pristanic acid in intact fibroblasts.

Dihydroxyacetone-phosphate acyltransferase (DHAPAT) is a peroxisomal enzyme catalysing the first step in ether-phospholipid biosynthesis. DHAPAT is deficient in cells from patients suffering from a variety of peroxisomal disorders. Accurate measurement of the activity of this enzyme is of great importance, especially since it is a central parameter in the prenatal diagnosis of the disorders of peroxisome biogenesis, rhizomelic chondrodysplasia punctata and DHAPAT-deficiency. We describe a straightforward and accurate assay allowing the activity of DHAPAT to be measured reliably in chorionic villus samples, blood cells, cultured skin fibroblasts, cultured chorionic villus fibroblasts and cultured amniocytes.

Identification of a patient as suffering from a peroxisomal disorder usually starts by the finding of elevated very long-chain fatty acids in plasma and/or serum. This is followed by more detailed studies in blood, fibroblasts and tissues, including immunoblot analysis. Indeed, immunoblot analysis has become a valuable tool in the correct diagnosis and assignment of individual patients, except for X-linked adrenoleukodystrophy (X-ALD). We describe a simple immunoblotting procedure applicable to liver and fibroblast homo-genates using antibodies raised against catalase and the three beta-oxidation enzyme proteins acyl-CoA oxidase I, bifunctional protein and peroxisomal thiolase. The same procedure can also be used for chorionic villus biopsy specimens and has now become the method of choice for the prenatal diagnosis of Zellweger syndrome (and other disorders of peroxisome biogenesis) and rhizomelic chondrodysplasia punctata.

We describe two siblings, presently 5 and 9 years of age, who had neurodegenerative symptoms after the first year of life. Although they lacked clinical characteristics of a peroxisomal disorder, they had elevated levels of plasma very long chain fatty acids, pipecolic and phytanic acids, and abnormal bile acid intermediates, which suggested a generalized peroxisome deficiency disorder. Immunocytochemical study and electron microscopy of the liver disclosed absence of peroxisomes in approximately 90% of hepatocytes. However, the remaining 10% of the hepatocytes had numerous normal-looking peroxisomes containing catalase activity and catalase antigen. Alanine glyoxylate aminotransferase and the peroxisomal beta-oxidation enzymes acyl-coenzyme A oxidase and 3-ketoacyl coenzyme A thiolase were also present in the organelles. Both cell types were grouped in clusters. In contrast to most of the liver cells, fibroblasts cultured from skin biopsy specimens had normal peroxisomal functions. Thus this defect in peroxisome biogenesis is characterized by variable expression in different tissues (liver vs fibroblasts), as well as within individual cells in the same tissue (liver mosaicism). Awareness of the heterogeneity in tissue expression of peroxisomal disorders could be of critical importance in prenatal diagnosis.

Peroxisomal disorders represent a recently recognized group of inherited diseases in man, now comprising 14 different disorders. If discussion is restricted to those peroxisomal disorders in which there is neurological involvement (thereby excluding hyperoxaluria and acatalasaemia), results over the least few years have shown that analysis of very-long-chain fatty acids (VLCFAs) is a highly reliable initial test to establish whether or not one is dealing with a peroxisomal disorder. Rhizomelic chondrodysplasia punctata, its recently identified variant form and glutaryl-CoA oxidase deficiency will show no abnormalities and must be identified by other means. Recently we have found a few clinically proven cases of adrenoleukodystrophy showing normal VLCFA in plasma but clearly abnormal values in fibroblasts. This suggests that great care is warranted in interpreting plasma VLCFA analyses. Furthermore, plasma bile acids, phytanic acid, pristanic acid and pipecolic acid should be analysed in any patient with clinical symptoms suggestive for a peroxisomal disorder but normal plasma VLCFAs.

A boy aged 21 months who was being investigated for developmental delay and failure to thrive was found to have punctate epiphyseal calcification. He had no evidence of rhizomelic shortening of the limbs or cataracts. Investigation revealed defective plasmalogen synthesis due to isolated deficiency of dihydroxyacetonephosphate acyltransferase (DHAP-AT). The parents were consanguineous and a sister was similarly affected, suggesting autosomal recessive inheritance. Hitherto, recessively inherited isolated DHAP-AT deficiency has only been described in patients with a phenotype similar to that of rhizomelic chondrodysplasia punctata. This report indicates that the same biochemical disorder can be associated with a less severe phenotype.

In order to evaluate the efficacy of L-phenylalanine (L-Phe) in combination with UVA therapy for vitiligo an open trial (149 patients, 18 months) and a small double-blind trial (32 patients, 6 months) were conducted. Oral L-Phe loading resulted in peak plasma levels of L-Phe after 30-60 min and a slight increase in the plasma tyrosine level. Response to L-Phe plus UVA irradiation was positive, and various grades of repigmentation not exceeding 77% in the open and 60% in the blind trial were observed. An increased L-Phe dose resulted in increased L-Phe plasma levels but not in improved clinical results. The optimal L-Phe dose appears to be lower than 50 mg/kg/day. Although it is difficult to draw firm conclusions from the present investigation, we think that L-Phe may have a place in the treatment of vitiligo and its role merits further investigation.

We report a 7-year-old patient with chondrodysplasia punctata but without rhizomelia. He was born with typical clinical and radiological symptoms of this disease. He developed slowly with considerable psychomotor retardation but improved later, gaining some speech and psychosocial contacts. Joint contractures and bilateral cataracts are still major problems. De novo plasmalogen synthesis in fibroblasts was greatly reduced and DHAP-AT activity was at the lower limit of controls. Peroxisomal thiolase was present in its precursor form only. Membrane fluidity (measured by TMA-DPH fluorescence anisotropy) was increased in erythrocyte ghosts and in lymphocytes. Plasma phytanic acid concentration was elevated 5-fold. The patient represents a mild clinical course of chondrodysplasia punctata, resembling Conradi-Hünermann syndrome, but biochemically he has the typical peroxisomal dysfunction of rhizomelic chondrodysplasia punctata except for a high residual activity of DHAP-AT.

In the liver biopsy from an 8.5-year-old girl with the biochemical characteristics of rhizomelic chondrodysplasia punctata (RCDP), but with normal limbs, normal catalase-containing peroxisomes were absent. Light microscopy after diaminobenzidine staining for catalase activity (the peroxisomal marker enzyme) and immunostaining against catalase protein indicated a cytosolic localization of the enzyme. By electron microscopy, rare and extremely large, irregularly shaped vesicles were found in the parenchymal cells. The three peroxisomal beta-oxidation enzymes (acyl-CoA oxidase, bi(tri)functional enzyme, and 3-ketoacyl-CoA thiolase) and alanine-glyoxylate aminotransferase were immunolocalized in these organelles. However, a weak to negative label was obtained after staining against catalase. Diaminobenzidine staining demonstrated a minimal catalase reaction product in some vesicles only. Morphometry revealed a corrected mean d-circle of 1.44 microns and a maximum d-circle of 2.767 microns (controls: 0.635 microns and 1.027 microns, respectively). Numerical, volume, and surface densities were reduced to 3%, 41%, and 17% of control values, respectively. The large size, irregular shape, and rarity of the organelles are morphologic features of peroxisomal "ghosts." It seems that in this patient, apart from the known peroxisomal defects in RCDP, catalase incorporation into the peroxisomes is impaired together with a normal proliferation (division) of the organelles. In the cultured skin fibroblasts from the patient, however, immuno-electron microscopy showed normal catalase-containing peroxisomes in apparently normal numbers.

Profiles of saturated very-long-chain (> C22) fatty acids were studied in plasma, fibroblasts, erythrocytes, platelets, and leukocytes of patients affected by peroxisomal disorders such as Zellweger syndrome, X-linked adrenoleukodystrophy (X-ALD), and classic rhizomelic chondrodysplasia punctata (RCDP) and in controls. In Zellweger patients, the concentration of hexacosanoic acid (C26:0) and the C26:0/C22:0 ratio are greatly increased in plasma and fibroblasts. However, the plasma concentration of docosanoic acid (C22:0) is greatly decreased. Also in platelets, leukocytes, and to a lesser extent erythrocytes, the C26:0 concentrations and both the C26:0/C22:0 and C24:0/C22:0 ratios are greatly increased. The C24:0/C22:0 ratio is significantly increased in plasma, platelets, and leukocytes, but not in erythrocytes. In X-ALD, the C26:0 concentration and the C26:0/C22:0 and C24:0/C22:0 ratios are significantly increased in plasma, fibroblasts, platelets, and leukocytes, but the erythrocytes show substantial overlap in the 5-90% ranges between controls and patients. In RCDP, slightly increased C26:0 and C26:0/C22:0 ratios are found in erythrocytes, platelets, and leukocytes, but not in plasma and fibroblasts. We conclude that plasma and fibroblasts are the specimens of choice for biochemical diagnosis of Zellweger syndrome and X-ALD, respectively. The slight increase in C26:0 in blood cells of RCDP patients suggests a decreased flux of very-long-chain fatty acids through the peroxisomal beta-oxidation pathway in liver in this genetic disorder.

In 16 consecutive patients with clinically suspected and biochemically proven X-linked adrenoleukodystrophy (X-ALD), total delay (interval between onset of symptoms and diagnosis) and specialist delay (interval between referral to a specialist and diagnosis) were determined. All patients previously were unaware of the existence of X-ALD in their families. From the time of onset of symptoms attributable to this disease until diagnosis, mean total delay was 9.9 (range 1-33) years and mean specialist delay was 8.4 (range 0-33) years. Three patients who presented with adrenocortical insufficiency had mean total and specialist delays of 17.3 (range 9-33) years. Five patients with an initial diagnosis of multiple sclerosis had mean total and specialist delays of 12.8 (range 5-25) and 11.2 (range 1-23) years, respectively. In 12 patients with adrenomyeloneuropathy--the second most frequent phenotype of X-ALD--mean total delay was 11.0 (range 2-33) years and mean specialist delay 9.1 (range 0-33) years. Since 1981 X-ALD can be reliably diagnosed on the basis of elevated levels of very long chain fatty acids in plasma and/or cultured fibroblasts. The delays therefore must have been due to the unfamiliarity with the clinical manifestations and diagnostic possibilities of this disease. Once X-ALD is diagnosed, dietary treatment and/or bone marrow transplantation may be considered. Genetic counseling should be performed, and screening of other family members is essential for the early identification of affected relatives.

We describe a 16-year-old boy suffering from psychomotor retardation, sensorineuronal hearing impairment, peripheral neuropathy, hepatosplenomegaly, short stature and delayed puberty. Postnatally, muscular hypotonia, mild facial dysmorphism and delayed fontanelle closure had been noticed. At the time of our examination, adrenal cortical function was normal. Biochemical analysis revealed accumulation of very long (> C22) chain fatty acids in plasma and fibroblasts. Furthermore, elevated levels of intermediates of bile acid synthesis and phytanic acid were detectable. These findings are consistent with a defect in the peroxisomal beta-oxidation system. A generalised defect of peroxisomal function was excluded by normal plasmalogen levels in erythrocytes and normal plasmalogen de novo synthesis in fibroblasts. Immunoblotting of the peroxisomal beta-oxidation enzymes gave normal results suggesting retained immunoreactivity but catalytic inactivity of one of the enzymes involved, probably either the trifunctional protein or the peroxisomal ketothiolase. This case markedly differs clinically from the few published reports on isolated deficiencies of peroxisomal beta-oxidation. Among the patients with comparable biochemical findings, this is the first report of survival into adolescence.

An infant with the characteristic phenotype of classical rhizomelic chondrodysplasia punctata was found to have an isolated deficiency of the peroxisomal enzyme acyl CoA dihydroxyacetone phosphate acyltransferase (DHAP-AT). All other peroxisomal functions measured were found to be normal. Previously described in one other case report, this confirms the existence of another distinct form of peroxisomal disorder characterised biochemically by a deficiency in de novo plasmalogen biosynthesis only.

The degradation of leukotrienes by beta-oxidation from the omega-end proceeds in peroxisomes (Jedlitschky et al. J. Biol. Chem. 1991. 266:24763-24772). Peroxisomal degradation of leukotrienes was studied in humans by analyses of endogenous leukotrienes in urines from eight patients with biochemically established peroxisome deficiency disorder and eight age- and sex-matched healthy infant controls. Leukotriene metabolites were separated by high-performance liquid chromatography, quantified by radioimmunoassays, and identified as well as quantified by gas chromatography-mass spectrometry. Urinary leukotriene E4 (LTE4) and N-acetyl-LTE4 excretions, relative to creatinine, were increased > 10-fold in the patients in comparison to healthy infants. The beta-oxidation product omega-carboxy-tetranor-LTE3 averaged 0.05 mumol/mol creatinine in the controls but was not detectable in the patients. However, omega-carboxy-LTE4 (median 13.6 mumol/mol creatinine) was significantly increased in the patients' urine, whereas LTB4 (median 0.07 mumol/mol creatinine) and omega-carboxy-LTB4 were detected exclusively in the urines of the patients. These data indicate an impairment of the inactivation and degradation of both LTE4 and LTB4 in patients with peroxisomal deficiency. The increased levels of the biologically active, proinflammatory mediators LTE4 and LTB4 might be of pathophysiological significance in peroxisome deficiency disorders. This is the first and so far only condition with a pronounced urinary excretion of omega-carboxy-LTE4, omega-carboxy-LTB4, and LTB4. This impaired catabolism of leukotrienes and the altered pattern of metabolites may be of diagnostic value. These findings underline the essential role of peroxisomes in the catabolism of leukotrienes in humans.