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Biomedical subjects

A Superti-Furga

Publications and source records attributed to A Superti-Furga.

At least 55 records · Page 3Linked to original sources
PubMed1998

Schwartz-Jampel syndrome type 2 and Stüve-Wiedemann syndrome: a case for "lumping".

Recent studies demonstrated the existence of a genetically distinct, usually lethal form of the Schwartz-Jampel syndrome (SJS) of myotonia and skeletal dysplasia, which we called SJS type 2. This disorder is reminiscent of another rare condition, the Stüve-Wiedemann syndrome (SWS), which comprises campomelia at birth with skeletal dysplasia, contractures, and early death. To test for possible nosologic identity between these disorders, we reviewed the literature and obtained a follow-up of the only two surviving patients, one with SJS type 2 at age 10 years and another with SWS at age 7 years. Patients reported as having either neonatal SJS or SWS presented a combination of a severe, prenatal-onset neuromuscular disorder (with congenital joint contractures, respiratory and feeding difficulties, tendency to hyperthermia, and frequent death in infancy) with a distinct campomelic-metaphyseal skeletal dysplasia. The similarity of the clinical and radiographic findings is so extensive that these disorders appear to be a single entity. The follow-up observation of an identical and unique pattern of progressive bone dysplasia in the two patients (one with SJS type 2, one with SWS) surviving beyond infancy adds to the evidence in favor of identity. The hypothesis that SWS and SJS type 2 are the same disorder should be testable by molecular methods.

Abnormalities, Multiple↗
PubMed1998

Clinical homogeneity of the Stüve-Wiedemann syndrome and overlap with the Schwartz-Jampel syndrome type 2.

The Stüve-Wiedemann syndrome (SWS) is a rare disorder characterized by respiratory distress, hyperthermic episodes, and early lethality and radiologically by bowing of the long bones with internal cortical thickening and large metaphyses. We report findings in 8 new patients suggesting that this syndrome is clinically homogeneous. All patients had feeding and swallowing difficulties, respiratory insufficiency, abnormal appearance, muscle hypotonia, and postnatal short stature. Recurrent episodes of unexplained fever occurred in all and were the cause of death in 6 of 8 cases. Parental consanguinity and sib recurrence suggest autosomal recessive inheritance. The clinical, radiological, and histological similarities between our patients with SWS and those with the recently delineated "neonatal" Schwartz-Jampel syndrome (SJS type 2) lead us to suggest that SWS and SJS type 2 may be a single entity.

Abnormalities, Multiple↗
PubMed1998

The human glutaryl-CoA dehydrogenase gene: report of intronic sequences and of 13 novel mutations causing glutaric aciduria type I.

Glutaric acidemia type I (GAI) (McKusick 231670) is an autosomal recessive disease affecting the catabolism of the amino acids lysine, hydroxylysine and tryptophan, caused by a defect in the gene encoding glutaryl-coenzyme A dehydrogenase (GCDH) and associated with severe neurological symptoms. Several pathogenic mutations in GCDH have been reported to cause GAI. One mutation, R402W, is more common than the others, which seem to be private" mutations. Here we report the entire sequences of introns 1, 2, 3, 6, 7, 8 and 9, and part of those of introns 4, 5 and 10 as well as 21 different mutations in 20 patients with GAI, corresponding to 38 out of 40 alleles.

Amino Acid Metabolism, Inborn Errors↗
PubMed1998

Proteoglycan sulfation in cartilage and cell cultures from patients with sulfate transporter chondrodysplasias: relationship to clinical severity and indications on the role of intracellular sulfate production.

Mutations in the diastrophic dysplasia sulfate transporter (DTDST) gene have been associated with a family of chondrodysplasias that includes diastrophic dysplasia (DTD), atelosteogenesis type 2 (AO2) and the lethal condition achondrogenesis type 1B (ACG1B). There is a correlation between the nature of the mutations and the clinical phenotype, but our understanding of the pathophysiology of the disorder, which involves defective sulfation of cartilage proteoglycans, is far from complete. To evaluate the degree of proteoglycan undersulfation in vivo, we have extracted chondroitin sulfate proteoglycans from cartilage of twelve patients with sulfate transporter chondrodysplasias and analyzed their disaccharide composition by HPLC after digestion with chondroitinase ABC. The amount of non-sulfated disaccharide was elevated in patients' samples (controls, 5.5%+/-2.8 (n=10); patients, 11% to 77%), the highest amount being present in ACG1B patients, indicating that undersulfation of chondroitin sulfate proteoglycans occurs in cartilage in vivo and is correlated with the clinical severity. To investigate further the biochemical mechanisms responsible for the translation of genotype to phenotype, we have studied fibroblast cultures of patients with DTD, AO2 and ACG1B, and controls, by double-labelling with [35S]sulfate and [3H]glucosamine. The incorporation of extracellular sulfate, estimated by the 35S/3H ratio in proteoglycans, was reduced in all patients' cells, with ACG1B cells showing the lowest values. However, disaccharide analysis of chondroitin sulfate proteoglycans showed that these were normally sul fated or only moderately undersulfated; marked undersulfation was observed only after addition of the artificial glycosaminoglycan-chain initiator, beta-D-xyloside, to the culture medium. These results suggest that, while utilization of extracellular sulfate is impaired, fibroblasts can replenish their intracellular sulfate pool by oxidizing sulfur-containing compounds (such as cysteine) and thus partially rescue PG sulfation under basal conditions. This rescue pathway becomes insufficient when GAG synthesis rate is stimulated by beta-D-xyloside. These findings may explain why phenotypic consequences of DTDST mutations are restricted to cartilage, a tissue with high GAG synthesis rate and poor vascular supply, and imply that pharmacological therapy aimed at restoring the intracellular sulfate pool might improve PG sulfation in DTD and related disorders.

Anion Transport Proteins↗
PubMed1998

Diagnosis and management of glutaric aciduria type I.

Glutaric aciduria type I (GA1) is a preventable cause of acute brain damage in early childhood, leading to a severe dystonic-dyskinetic disorder that is similar to cerebral palsy and ranges from extreme hypotonia to choreoathetosis to rigidity with spasticity. Degeneration of the putamen and caudate typically occurs between 6 and 18 months of age and is probably linked to changes in metabolic demand caused by normal maturational changes and superimposed catabolic stress. Recognition of this biochemical disorder before the brain has been injured is essential to outcome. Diagnosis depends upon the recognition of relatively non-specific physical findings such as hypotonia, irritability and macrocephaly, and on performance of urine organic acid quantification by gas chromatography--mass spectrometry or selective searches of urine or blood specimens by tandem mass spectrometry for glutarylcarnitine. The diagnosis may also be suggested by characteristic findings on neuroimaging. In selected patients diagnosis can only be reached by enzyme assay. Specific current management by the authors of this paper includes pharmacological doses of L-carnitine, as well as dietary protein restriction. Metabolic decompensation must be treated aggressively to avoid permanent brain damage. Multicentre studies are needed to establish best methods of diagnosis and optimal therapy of this disorder.

Amino Acid Metabolism, Inborn Errors↗
PubMed1998

Mutations in orthologous genes in human spondyloepimetaphyseal dysplasia and the brachymorphic mouse.

The osteochondrodysplasias are a genetically heterogeneous group of disorders affecting skeletal development, linear growth and the maintenance of cartilage and bone. We have studied a large inbred Pakistani family with a distinct form of recessively inherited spondyloepimetaphyseal dysplasia (SEMD) and mapped a gene associated with this dwarfing condition to chromosome 10q23-24, a region syntenic with the locus for the brachymorphic mutation on mouse chromosome 19. We identified two orthologous genes, ATPSK2 and Atpsk2, encoding novel ATP sulfurylase/APS kinase orthologues in the respective regions of the human and mouse genomes. We characterized a nonsense mutation in ATPSK2 in the SEMD family and a missense mutation in the region of Atpsk2 encoding the APS kinase activity in the brachymorphic mouse. ATP sulfurylase/APS kinase catalyses the metabolic activation of inorganic sulfate to PAPS, the universal donor for post-translational protein sulfation in all cell types. The cartilage-specificity of the human and mouse phenotypes provides further evidence of the critical role of sulfate activation in the maturation of cartilage extracellular matrix molecules and the effect of defects in this process on the architecture of cartilage and skeletogenesis.

Amino Acid Sequence↗
PubMed1998

Mutation and deletion of the pseudoautosomal gene SHOX cause Leri-Weill dyschondrosteosis.

Leri-Weill Dyschondrosteosis (LWD; OMIM 127300) is a dominantly inherited skeletal dysplasia characterized by disproportionate short stature with predominantly mesomelic limb shortening. Expression is variable and consistently more severe in females, who frequently display the Madelung deformity of the forearm (shortening and bowing of the radius with dorsal subluxation of the distal ulna). The rare Langer Mesomelic Dysplasia (LD; OMIM 249700), characterized by severe short stature with hypoplasia/aplasia of the ulna and fibula, has been postulated to be the homozygous form of LWD (refs 4-6). In a six-generation pedigree with LWD, we established linkage to the marker DXYS6814 in the pseudoautosomal region (PAR1) of the X and Y chromosomes (Z max=6.28; theta=0). Linkage analysis of three smaller pedigrees increased the lod score to 8.68 (theta=0). We identified submicroscopic PAR1 deletions encompassing the recently described short stature homeobox-containing gene SHOX (refs 7,8) segregating with the LWD phenotype in 5 families. A point mutation leading to a premature stop in exon 4 of SHOX was identified in one LWD family.

Amino Acid Sequence↗
PubMed1997

Undersulfation of cartilage proteoglycans ex vivo and increased contribution of amino acid sulfur to sulfation in vitro in McAlister dysplasia/atelosteogenesis type 2.

Mutations in the diastrophic dysplasia sulfate transporter gene cause a family of chondrodysplasias including, in order of increasing severity, diastrophic dysplasia, atelosteogenesis type 2 and achondrogenesis type 1B. McAlister dysplasia is a lethal chondrodysplasia considered on the basis of minor radiographic features to be a disorder different from atelosteogenesis type 2. Here, we demonstrate that McAlister dysplasia arises from mutations in the diastrophic dysplasia sulfate transporter gene and that this disorder essentially coincides on molecular and biochemical grounds with atelosteogenesis type 2. The fetus affected by McAlister dysplasia we have studied is a compound heterozygote for mutations leading to R279W and N425D substitutions in the diastrophic dysplasia sulfate transporter. Proteoglycan sulfation was studied in epiphyseal cartilage and in chondrocyte cultures of the patient by high performance liquid chromatography of chondrotinase digested proteoglycans; a high amount of non-sulfated disaccharide was observed as a consequence of the alteration of the transporter function caused by the mutations. However, sulfated disaccharides were detectable even if in low amounts, both in cultured cells and tissue. Functional impairment of the sulfate transporter was demonstrated in vitro by reduced incorporation of [35S]sulfate relative to [3H]glucosamine in proteoglycans synthesized by chondrocytes and by sulfate-uptake assays in fibroblasts. Parallel in vitro studies in a patient with achondrogenesis 1B indicated that the severity of the clinical phenotype seems to be correlated to the residual activity of the sulfate transporter. The capacity of fibroblasts to use cysteine as an alternative source of sulfate was evaluated by double-labeling experiments. Relative incorporation of [35S]cysteine-derived sulfate in the glycosaminoglycan chains was increased in the patient's cells, indicating that, in vitro, the catabolism of sulfur-containing amino acids can partially compensate for intracellular sulfate deficiency. Residual sulfation observed in proteoglycans extracted from cartilage suggests that this mechanism may be operating also in vivo.

Anion Transport Proteins↗
PubMed1997

Heterogeneity in Schwartz-Jampel chondrodystrophic myotonia.

UNLABELLED: The Schwartz-Jampel syndrome (SJS; chondrodystrophic myotonia; McK 255,800) is a recessively inherited condition defined by myotonia, short stature, and bone dysplasia. Genetic linkage between SJS and chromosomal region 1q36-34 has been observed in several families, but the gene has not yet been identified. We studied the clinical and radiological features in 81 patients from the literature and 5 own patients trying to identify distinct subgroups. In addition, we tested genetic linkage to the SJS locus on chromosome 1 in one family with two affected sibs. We found that a group of patients have mild skeletal changes which may be secondary consequences of myotonia, while another group of patients appear to have primary bone dysplasia with myotonia. Within this latter group, there are differences in age of manifestation, clinical course and pattern of bone changes. We tentatively isolate three different types of SJS: type 1A, usually recognized in childhood, with moderate bone dysplasia, corresponding to the original descriptions of Schwartz, Jampel and Aberfeld; type 1B, similar to type 1A but recognizable at birth, with more pronounced bone dysplasia resembling Kniest dysplasia; and type 2, manifest at birth, with increased mortality and bone dysplasia resembling Pyle disease. Genetic analysis of the family with two sibs affected by SJS type 2 showed evidence against linkage to chromosome 1p36-34. CONCLUSIONS: SJS is clinically and radiologically heterogeneous. The causes of heterogeneity are not known yet but are likely to include both different mutations at the SJS locus on chromosome 1 and the presence of a second SJS locus. A tentative clinico-radiological classification can be useful for the characterization of patients and the development of genotype-phenotype correlations.

Adolescent↗
PubMed1997

Glutaric aciduria type 1 (glutaryl-CoA-dehydrogenase deficiency): advances and unanswered questions. Report from an international meeting.

Infants with macrocephaly, young children with acute disease resembling encephalitis, and children with truncal hypotonia, ataxia, or dystonia may be affected by glutaric aciduria type I (GA 1, glutaryl-CoA-dehydrogenase deficiency), a not-so-rare autosomal recessive neurometabolic disease. Well-known features of GA1 are fronto-temporal brain atrophy with macrocephaly and acute encephalopathic episodes with striatal necrosis followed by dystonia, but some patients develop motor disease without overt crises and other biochemically affected individuals remain asymptomatic. Biochemical and molecular characterization is available and allows post- and prenatal diagnosis. The pathogenesis of fronto-temporal atrophy, macrocephaly, and basal ganglia necrosis is still not understood, and there is no close correlation between biochemical parameters and clinical outcome. There is, however, evidence suggesting that carnitine supplementation and anticatabolic treatment of intercurrent illness may arrest or prevent neurological deterioration, while the role of limitation of dietary lysine and tryptophane is not yet clear. Although pathogenetic aspects are poorly understood, the natural course of glutaric aciduria type 1 can be changed by early diagnosis and treatment. Coordinated research is needed to understand the pathogenesis of brain toxicity, to define the role of dietary therapy, and to explore the possibility of neonatal screening.

Brain Diseases↗
PubMed1997

Detection and characterization of mitochondrial DNA rearrangements in Pearson and Kearns-Sayre syndromes by long PCR.

We used a strategy based on long PCR (polymerase chain reaction) for detection and characterization of mitochondrial DNA (mtDNA) rearrangements in two patients with clinical signs suggesting Pearson syndrome and Kearns-Sayre syndrome (KSS), respectively, and one patient with myopathic symptoms of unidentified origin. Mitochondrial DNA rearrangements were detected by amplification of the complete mitochondrial genome (16.6 kb) using long PCR with primers located in essential regions of the mitochondrial genome and quantified by three-primer PCR. Long PCR with deletion-specific primers was used for identification and quantitative estimation of the different forms of rearranged molecules, such as deletions and duplications. We detected significant amounts of a common 7.4-kb deletion flanked by a 12-bp direct repeat in all tissues tested from the patient with Pearson syndrome. In skeletal muscle from the patient with clinical signs of KSS we found significant amounts of a novel 3.7-kb rearrangement flanked by a 4-bp inverted repeat that was present in the form of deletions as well as duplications. In the patient suffering from myopathic symptoms of unidentified origin we did not detect rearranged mtDNA in blood but found low levels of two rearranged mtDNA populations in skeletal muscle, a previously described 7-kb deletion flanked by a 7-bp direct repeat and a novel 6.6-kb deletion with no repeat. These two populations, however, were unlikely to be the cause of the myopathic symptoms as they were present at low levels (10-40 ppm). Using a strategy based on screening with long PCR we were able to detect and characterize high as well as low levels of mtDNA rearrangements in three patients.

Adolescent↗
PubMed1997

The effect of the N-methyl-D-aspartate receptor antagonist dextromethorphan on perioperative brain injury in children undergoing cardiac surgery with cardiopulmonary bypass: results of a pilot study.

Experimental evidence indicates a role of the N-methyl-D-aspartate receptor in the pathogenesis of brain injury occurring during cardiac surgery with cardiopulmonary bypass (CPB). Dextromethorphan is a noncompetitive antagonist of this receptor with a favorable safety profile. Thirteen children age 3-36 months undergoing cardiac surgery with expected CPB of 60 minutes or more were randomly assigned to treatment with dextromethorphan (36-38 mg/kg/day) or placebo administered by naso-gastric tube. Dextromethorphan was absorbed well and reached putative therapeutic levels in blood and cerebrospinal fluid. Adverse effects were not observed. Mild hemiparesis developed after operation in one child of each group, and severe encephalopathy in one of the placebo group. Sharp waves were recorded in postoperative continuous electroencephalography in all placebo (n = 7) but only in 2/6 dextromethorphan treated children (p = 0.02). Pre- and postoperative cranial magnetic resonance imaging (MRI) revealed less pronounced ventricular enlargement in the dextromethorphan group (not significant). An increase of periventricular white matter lesions was visible in two placebo-treated children only. No elevations of cerebrospinal fluid enzymes were observed in either group. Although children with dextromethorphan showed less abnormalities in electroencephalography and MRI, dissimilarities of the treatment groups by chance diminished conclusions to possible protective effects of dextromethorphan at this time.

Brain Chemistry↗
PubMed1996

Undersulfation of proteoglycans synthesized by chondrocytes from a patient with achondrogenesis type 1B homozygous for an L483P substitution in the diastrophic dysplasia sulfate transporter.

Achondrogenesis type 1B is an autosomal recessive, lethal chondrodysplasia caused by mutations in the gene encoding a sulfate/chloride antiporter of the cell membrane (Superti-Furga, A., Hästbacka, J., Wilcox, W. R., Cohn, D. H., van der Harten, J. J., Rossi, A., Blau, N., Rimoin, D. L., Steinmann, B., Lander, E. S., and Gitzelmann, R.(1996) Nat. Genet. 12, 100-102). To ascertain the consequences of the sulfate transport defect on proteoglycan synthesis, we studied the structure and sulfation of proteoglycans in cartilage tissue and in fibroblast and chondrocyte cultures from a fetus with achondrogenesis 1B. Proteoglycans extracted from epiphyseal cartilage and separated on agarose gels migrated more slowly than controls and stained poorly with alcian blue. The patient's cultured cells showed reduced incorporation of [35S]sulfate relative to [3H]glucosamine, impaired uptake of sulfate, and higher resistance to chromate toxicity compared to control cells. Epiphyseal chondrocytes cultured in alginate beads synthesized proteoglycans of normal molecular size as judged by gel filtration chromatography, but undersulfated as judged by ion exchange chromatography and by the amount of nonsulfated disaccharide. High performance liquid chromatography analysis of chondroitinase-digested proteoglycans showed that sulfated disaccharides were present, although in reduced amounts, indicating that at least in vitro, other sources of sulfate can partially compensate for sulfate deficiency. A t1475c transition causing a L483P substitution in the eleventh transmembrane domain of the sulfate/chloride antiporter was present on both alleles in the patient who was the product of a consanguineous marriage. The results indicate that the defect of sulfate transport is expressed in both chondrocytes and fibroblasts and results in the synthesis of proteoglycans bearing glycosaminoglycan chains which are poorly sulfated but of normal length.

Achondroplasia↗
PubMed1996

A specific collagen type II gene (COL2A1) mutation presenting as spondyloperipheral dysplasia.

We report on a patient with a skeletal dysplasia characterized by short stature, spondylo-epiphyseal involvement, and brachydactyly E-like changes. This condition has been described as spondyloperipheral dysplasia and the few published cases suggest autosomal dominant inheritance with considerable clinical variability. We found our sporadic case to be due to a collagen type II defect resulting from a specific COL2A1 mutation. This mutation is the first to be located at the C-terminal outside the helical domain of COL2A1. A frameshift as consequence of a 5 bp duplication in exon 51 leads to a stop codon. The resulting truncated C-propeptide region seems to affect helix formation and produces changes of chondrocyte morphology, collagen type II fibril structure and cartilage matrix composition. Our case with its distinct phenotype adds another chondrodysplasia to the clinical spectrum of type II collagenopathies.

Amino Acid Sequence↗
PubMed1996

A chondrodysplasia family produced by mutations in the diastrophic dysplasia sulfate transporter gene: genotype/phenotype correlations.

Achondrogenesis type 1B (ACG-1B), atelosteogenesis type 2 (AO-2), and diastrophic dysplasia (DTD) are recessively inherited chondrodysplasias of decreasing severity caused by mutations in the diastrophic dysplasia sulfate transporter (DTDST) gene on chromosome 5. In these conditions, sulfate transport across the cell membrane is impaired which results in insufficient sulfation of cartilage proteoglycans and thus in an abnormally low sulfate content of cartilage. The severity of the phenotype correlates well with the predicted effect of the underlying DTDST mutations: homozygosity or compound heterozygosity for stop codons or transmembrane domain substitutions mostly result in achondrogenesis type 1B, while other structural or regulatory mutations usually result in one of the less severe phenotypes. The chondrodysplasias arising at the DTDST locus constitute a bone dysplasia family with recessive inheritance.

Animals↗