1/53. Enlarged nuchal translucency and low serum protein concentrations as possible markers for zellweger syndrome. We present a case of a fetus in which an enlarged nuchal translucency was detected at 12 weeks' gestation. The karyotype was normal. Subsequent ultrasound examination showed no obvious fetal abnormalities apart from a mild pericardial effusion. serum screening revealed very low concentrations of estriol and human chorionic gonadotropin. After birth the diagnosis of zellweger syndrome was made. Nuchal translucency screening, estriol level identification and detailed ultrasound scanning may help to identify fetuses affected by this syndrome. ( info) |
| We describe the main clinical and biochemical findings in 15 patients with peroxisomal disorders, together with the results of 11 prenatal investigations for zellweger syndrome. The initial laboratory diagnosis depended in most cases on demonstration of elevated very long chain fatty acids in plasma, but follow-up studies using cultured fibroblasts were essential for complete classification. The patient group comprises nine cases of zellweger syndrome, one of neonatal adrenoleucodystrophy, two of infantile refsum disease, one of bifunctional protein deficiency, and two of rhizomelic chondrodysplasia punctata. The study illustrates the clinical and biochemical variability of this group of patients and the detailed studies that are required for classification. ( info) |
3/53. Developmental and pathological expression of peroxisomal enzymes: their relationship of D-bifunctional protein deficiency and zellweger syndrome. We present the developmental changes of peroxisomal enzymes, catalase, L-bifunctional protein (L-BF) and D-bifunctional protein (D-BF), in the normal brains, and patients with D-BF deficiency, a new peroxisomal disease. D-BF immunoreactivity was observed in controls as early as 13 gestational weeks (GW) and increased with maturation. The adult pattern with fine granule staining of somata and dendrites became apparent in adolescence. L-BF appeared at 20 GW in the cerebral cortex and purkinje cells and positive glia appeared early in the white matter at 17 GW, and then increased with age. catalase-positive neurons were identified in the same manner as L-BF, D-BF deficiency in both fetus and infant showed markedly diminished enzyme immunoreactivity. patients demonstrate reduced D-BF expression. zellweger syndrome shows decreased expression for the three proteins. This study shows that the peroxisomal enzymes may be closely related to neuronal maturation and gliogenesis in human brain and to disturbance of neuronal migration as seen in zellweger syndrome significant. D-BF deficiency may exhibit a range of symptoms during the neonatal and early infantile periods some of which may be similar to zellweger syndrome. ( info) |
4/53. Defective peroxisome membrane synthesis due to mutations in human PEX3 causes zellweger syndrome, complementation group G. Zellweger cerebro-hepato-renal syndrome is a severe congenital disorder associated with defective peroxisomal biogenesis. At least 23 PEX genes have been reported to be essential for peroxisome biogenesis in various species, indicating the complexity of peroxisomal assembly. Cells from patients with peroxisomal biogenesis disorders have previously been shown to segregate into >/=12 complementation groups. Two patients assigned to complementation group G who had not been linked previously to a specific gene defect were confirmed as displaying a cellular phenotype characterized by a lack of even residual peroxisomal membrane structures. Here we demonstrate that this complementation group is associated with mutations in the PEX3 gene, encoding an integral peroxisomal membrane protein. Homozygous PEX3 mutations, each leading to C-terminal truncation of PEX3, were identified in the two patients, who both suffered from a severe zellweger syndrome phenotype. One of the mutations involved a single-nucleotide insertion in exon 7, whereas the other was a single-nucleotide substitution eight nucleotides from the normal splice site in the 3' acceptor site of intron 10. Expression of wild-type PEX3 in the mutant cell lines restored peroxisomal biogenesis, whereas transfection of mutated PEX3 cDNA did not. This confirmed that the causative gene had been identified. The observation of peroxisomal formation in the absence of morphologically recognizable peroxisomal membranes challenges the theory that peroxisomes arise exclusively by growth and division from preexisting peroxisomes and establishes PEX3 as a key factor in early human peroxisome synthesis. ( info) |
5/53. A case of zellweger syndrome with extensive MRI abnormalities and unusual EEG findings. Differential diagnosis in a newborn with dysmorphic features and profound neurologic dysfunction should include the cerebro-hepato-renal syndrome of Zellweger. Its distinct clinical features, markedly elevated plasma levels of very long chain fatty acids and characteristic radiological findings support the diagnosis, which can now be confirmed by genetic markers. Quite consistent abnormalities of the neurophysiological studies in this syndrome have also been reported. We report a case with typical clinical and biochemical findings in whom distinctive brain MRI abnormalities were found. The results of neurophysiological studies with an unusual EEG pattern of continuous negative vertex sharp waves and spikes are discussed. We believe that such a pattern could be considered as a pathognomonic EEG finding, especially in cases of zellweger syndrome with extensive brain abnormalities and may even be closely associated with cortical dysplasias. ( info) |
| zellweger syndrome is a fatal autosomal-recessive hereditary disease characterized by the absence of peroxisomes in liver and kidneys. The absence of peroxisomes results in impairment of many metabolic pathways, especially beta-oxidation of very long chain fatty acids (VLCFAs). We report a case of a three-month-old male infant with facial dysmorphism, hypotonia, psychomotor retardation, and hepatomegaly. He had an elder brother with the same facial features and hypotonia who died of hepatic failure at four months of age. Biochemical studies revealed elevation of blood pipecolic acid and VLCFAs, compatible with peroxisomal disorder. Electron microscopy of liver biopsy revealed absence of peroxisomes. zellweger syndrome was diagnosed. Because this syndrome is usually fatal in early life, genetic counseling and prenatal diagnosis are crucial. ( info) |
| Peroxisome biogenesis disorders (PBD) are classified into zellweger syndrome (ZS), infantile refsum disease (IRD) and neonatal adrenoleukodystrophy. Disturbances in the differentiation of neural cells such as migration arrest are characteristic of PBD. So far the pathogenesis of these disturbances is not clearly understood. We describe an altered metabolism of glycosphingolipids in PBD which has not yet been investigated. We observed an increased amount of a-series gangliosides, GM2, GM1 and GD1a, in the fibroblasts of patients with ZS and IRD. gangliosides GM1 and GD1a were not present in detectable amounts in normal subjects. A key step in the synthesis of a-series gangliosides is a transfer of GalNAc to ganglioside GM3, so we determined the level of ganglioside GM3 by immunohistochemical methods. We found a granular structure, which was positive toward anti-ganglioside GM3 antibody in the cytoplasm of the patients' fibroblasts. In control cells, the cell membrane was slightly positive toward anti-GM3 antibody. These results may help to clarify the pathogenesis of PBD with respect to the functional roles of glycosphingolipids in cell differentiation, proliferation and apoptosis. ( info) |
| Cerebral metabolic abnormalities have been previously detected by 1H-MRS in infants with the zellweger syndrome as young as 3 months. We hypothesized that metabolic abnormalities could also be found shortly after birth. Two fullterm infants with zellweger syndrome were studied at 12 days and two months of age, respectively, using single voxel 1H-MRS. In the first case 1H-MRS was performed using PRESS with variable TE (31, 136, 272 ms); in the second, steam and PRESS sequences were used with different TE (steam at 30 and 144 ms; PRESS at 270 ms). In both cases a significant decrease of N-acetylaspartate (NAA) and an abnormal signal at 1.33 and 0.9 ppm, consisting of lactate (Lac) and lipids (Lip) were found. The reported MRS abnormalities, although not specific for peroxisomal dysfunctions, may support the suspicion of zellweger syndrome and may indicate direct referral to the specific laboratory and molecular studies necessary to establish the diagnosis and prognosis of this syndrome. ( info) |
9/53. First-trimester increased nuchal translucency and fetal hypokinesia associated with zellweger syndrome. We report the prenatal detection of increased nuchal translucency and decreased fetal movements, at 11 weeks of gestation, in a fetus at risk for zellweger syndrome. The diagnosis of zellweger syndrome was confirmed by metabolic studies on cultured chorionic villus sampling (CVS) cells and the pregnancy was terminated. The couple's subsequent pregnancy was monitored using the same method. In this pregnancy the nuchal translucency measured at 12 weeks' gestation was normal, the fetus was active, and biochemical studies using CVS and amniocentesis confirmed normal results. We believe this to be the first reported case of zellweger syndrome followed prenatally in which an increased nuchal translucency and fetal hypokinesia were detected in the first trimester. During the pregnancy with the affected child the maternal serum screen (MSS) showed low estriol level. We believe this to be the second report of a low estriol level on MSS in a pregnancy affected with zellweger syndrome. ( info) |
10/53. A new autosomal recessive syndrome with Zellweger-like manifestations. A son and daughter of consanguineous Ashkenazi Jewish parents presented with phenotypic features that are typically seen in zellweger syndrome: high forehead, broad nasal bridge, epicanthal fold, upslanting palpebral fissures, and micrognathia. In addition to the physical anomalies, they also have severe psychomotor retardation and hypotonia. However, results of peroxisomal studies including very long chain fatty acids and plasmalogen functions, were normal. There was partial deficiency of respiratory chain complexes. We suggest that this is a new autosomal recessive syndrome that could be due to a nuclear-encoded mitochondrial defect. ( info) |