PubMed Health⌕ Search

Biomedical subjects

R B Schutgens

Publications and source records attributed to R B Schutgens.

At least 19 recordsLinked to original sources
PubMed2001

Mutations of MLC1 (KIAA0027), encoding a putative membrane protein, cause megalencephalic leukoencephalopathy with subcortical cysts.

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.

Alleles↗
PubMed2001

Prenatal diagnosis of succinic semialdehyde dehydrogenase deficiency: increased accuracy employing DNA, enzyme, and metabolite analyses.

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.

Aldehyde Oxidoreductases↗
PubMed2001

Plasma placenta growth factor levels in midtrimester pregnancies.

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.

Adult↗
PubMed2001

Pharmacologic rescue of lethal seizures in mice deficient in succinate semialdehyde dehydrogenase.

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.

Aldehyde Oxidoreductases↗
PubMed2001

Subunits of the translation initiation factor eIF2B are mutant in leukoencephalopathy with vanishing white matter.

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.

Base Sequence↗
PubMed2000

2-Methylbutyryl-coenzyme A dehydrogenase deficiency: a new inborn error of L-isoleucine metabolism.

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.

Amino Acid Metabolism, Inborn Errors↗
PubMed1999

The gene for leukoencephalopathy with vanishing white matter is located on chromosome 3q27.

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.

Chromosome Mapping↗
PubMed1998

Iatrogenic isolated isoleucine deficiency as the cause of an acrodermatitis enteropathica-like syndrome.

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.

Acrodermatitis↗
PubMed1998

Lorenzo's oil and platelet activation in adrenomyeloneuropathy and asymptomatic X-linked adrenoleukodystrophy.

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.

Journal Article↗
PubMed1997

Smith-Lemli-Opitz syndrome diagnosed in a 130-year-old anatomical specimen.

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.

Cadaver↗
PubMed1997

A new peroxisomal beta-oxidation disorder in twin neonates: defective oxidation of both cerotic and pristanic acids.

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.

Diseases in Twins↗
PubMed1997

Highly increased CSF concentrations of cholesterol precursors in Smith-Lemli-Opitz syndrome.

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.

Cholestadienols↗
PubMed1997

Folate-responsive homocystinuria and megaloblastic anaemia in a female patient with functional methionine synthase deficiency (cblE disease).

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.

5-Methyltetrahydrofolate-Homocysteine S-Methyltran↗
PubMed1996

Metabolic aspects of peroxisomal disorders.

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.

Cholesterol↗
PubMed1996

Variant rhizomelic chondrodysplasia punctata (RCDP) with normal plasma phytanic acid: clinico-biochemical delineation of a subtype and complementation studies.

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.

Cells, Cultured↗