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J Bonaventure

Publications and source records attributed to J Bonaventure.

At least 55 records · Page 3Linked to original sources
PubMed1996

Clinical and genetic heterogeneity of hypochondroplasia.

Hypochondroplasia (HCH) is an autosomal dominant condition characterised by short stature, micromelia, and lumbar lordosis. In a series of 29 HCH probands (13 sporadic cases, 16 familial cases), we tested their DNA for the N540K recurrent mutation previously described in the proximal tyrosine kinase domain of the FGFR3 gene on chromosome 4p16.3, and we detected this mutation in 21/29 HCH patients. Interestingly, three familial cases were clearly unlinked to chromosome 4p16.3. Reviewing the clinical and radiological manifestations of the disease a posteriori, we observed that the N540K mutation was associated with relative macrocrania with a high and large forehead and short hands. By contrast, in the three pedigrees inconsistent with linkage to chromosome 4p16.3, the clinical phenotype was milder, macrocephaly and shortening of the long bones was less obvious, the hands were normal, and no metaphyseal flaring was noted. This study supports the view that HCH is a clinically and genetically heterogeneous condition.

Achondroplasia↗
PubMed1996

Mutations of the fibroblast growth factor receptor-3 gene in achondroplasia.

Achondroplasia (ACH), the most common cause of chondrodysplasia in man (1 in 15,000 live births), is an autosomal dominant condition of unknown origin characterized by short-limbed dwarfism and macrocephaly. Recently, a gene for ACH has been mapped to chromosome 4p16.3. The genetic interval encompassing the disease gene contains a member of the fibroblast growth factor receptor (FGFR) family which is expressed in articular chondrocytes (FGFR3). We report here recurrent missense mutations, in a CpG doublet of the transmembrane domain of the FGFR3 protein (G380R) in 17 sporadic cases and 6 unrelated familial forms of ACH and show that the mutant genotype segregates with the disease in these families. Thus, it appears that recurrent mutations of a single amino acid in the transmembrane domain of the FGFR3 protein account for all cases (23/23) of achondroplasia in our series.

Achondroplasia↗
PubMed1995

Substitution of aspartic acid for glycine at position 310 in type II collagen produces achondrogenesis II, and substitution of serine at position 805 produces hypochondrogenesis: analysis of genotype-phenotype relationships.

Two different mutations were found in two unrelated probands with lethal chondrodysplasias, one with achondrogenesis type II and the other with the less severe phenotype of hypochondrogenesis. The mutations in the COL2A1 gene were identified by denaturing gradient gel electrophoresis analysis of genomic DNA followed by dideoxynucleotide sequencing and restriction site analysis. The proband with achondrogenesis type II had a heterozygous single-base mutation that substituted aspartate for glycine at position 310 of the alpha 1(II) chain of type II procollagen. The proband with hypochondrogenesis had a heterozygous single-base mutation that substituted serine for glycine at position 805. Type II collagen extracted from cartilage from the probands demonstrated the presence of type I collagen and a delayed electrophoretic mobility, indicating post-translational overmodifications. Analysis of CNBr peptides showed that, in proband 1, the entire peptides were overmodified. Examination of chondrocytes cultured in agarose or alginate indicated that there was a delayed secretion of type II procollagen. In addition, type II collagen synthesized by cartilage fragments from the probands demonstrated a decreased thermal stability. The melting temperature of the type II collagen containing the aspartate-for-glycine substitution was reduced by 4 degrees C, and that of the collagen containing the serine-for-glycine substitution was reduced by 2 degrees C. Electron microscopy of the extracellular matrix from the chondrocyte cultures showed a decreased density of matrix and the presence of unusually short and thin fibrils. Our results indicate that glycine substitutions in the N-terminal region of the type II collagen molecule can produce more severe phenotypes than mutations in the C-terminal region. The aspartate-for-glycine substitution at position 310, which was associated with defective secretion and a probable increased degradation of collagen, is the most destabilizing mutation yet reported in type II procollagen.

Amino Acid Sequence↗
PubMed1995

Identification of COL2A1 gene mutations in patients with chondrodysplasias and familial osteoarthritis.

OBJECTIVE: To use a recently developed procedure for analysis of blood leukocyte DNA to detect mutations in the gene for type II procollagen (COL2A1) in patients with cartilage diseases ranging from early-onset familial osteoarthritis (OA) to lethal chondrodysplasias. METHODS: The technique of denaturing gradient gel electrophoresis was used to scan polymerase chain reaction (PCR) products from 45 exons and exon-flanking sequences of the COL2A1 gene in more than 70 patients with cartilage diseases whose severity ranged from mild to lethal. PCR products with abnormal migrations were then sequenced. RESULTS: Among the 3 patients with lethal hypochondrogenesis who were analyzed, all 3 were found to have a mutation in the COL2A1 gene. Among 17 patients with spondyloepiphyseal or spondyloepimetaphyseal dysplasia, 2 well-defined and 2 probable mutations were found. Among 15 patients with the Wagner-Stickler syndrome, 2 well-defined and 2 probable mutations were found. Among 45 patients with early-onset familial OA, 1 probable mutation was found. CONCLUSION: Using the procedure developed for analysis of the COL2A1 gene, mutations were detected in > 20% of patients with chondrodysplasias and up to 2% of patients with early-onset familial OA. However, these percentages are only minimal estimates because all possible mutations in the gene cannot be detected with this procedure.

Cartilage, Articular↗
PubMed1995

Genetic homogeneity of cartilage-hair hypoplasia.

Cartilage-hair hypoplasia (CHH) is an autosomal recessive metaphyseal chondrodysplasia characterized by short stature and hypoplasia of the hair. Associated pleiotropic features include deficient erythrogenesis, impaired T-cell mediated immunity, Hirschsprung's disease, and an increased risk of malignancies. CHH is most prevalent among the Old Order Amish in the United States and among the Finns, but sporadic families have been described among many other populations. We have previously mapped the gene for CHH to the short arm of chromosome 9 in Finnish and Amish families. The CHH locus resides close to D9S163 within an interval of 1.5 cM flanked by D9S165 and D9S50. In order to investigate the genetic homogeneity of CHH in various populations, we studied nine families with no genealogical connections to either Amish or Finns. No recombinants were detected between the CHH gene and any of the three closest marker loci studied, suggesting that CHH in these families results from mutation(s) at the same locus as in the Amish and Finnish families.

Canada↗
PubMed1995

Mutations in three subdomains of the carboxy-terminal region of collagen type X account for most of the Schmid metaphyseal dysplasias.

We have used the polymerase chain reaction and single strand conformation polymorphism (SSCP) methods to analyse the COL10A1 gene, which encodes collagen type X, in DNA samples from patients with metaphyseal dysplasia type Schmid (SMCD) and other related forms of metaphyseal dysplasia. Five cases of SMCD were sporadic and three others were familial. Abnormal SSCP profiles were observed in six instances. In two families, the altered pattern segregated with the phenotype. The heterozygous mutations corresponded to a glycine substitution by glutamic acid at position 595 and to an asparagine substitution by lysine at position 617. In one sporadic case, the sequence studies demonstrated that the individual was heterozygous for a single base deletion (del T 1908) that produced a premature stop codon. Three additional mutations were single base substitutions that affected highly conserved residues at positions 597, 644 and 648. In two additional individuals with SMCD, in two patients with unclassifiable forms of metaphyseal dysplasia, and in one family with epiphyso-metaphyseal dysplasia, SSCP analysis detected neutral polymorphisms in the entire coding sequence of the gene but no mutations. Our results demonstrate that mutations in the carboxy-terminal region of collagen X are specific for the SMCD phenotype. Mutations appear to be clustered into three small subdomains: one of them is rich an aromatic residues, the second includes the putative N-linked oligosaccharide attachment site and the third contains mostly hydrophilic residues. The absence of clinical variability between patients carrying heterozygous single base substitutions or small deletions suggests that, in both instances, the mutant collagen chains either fail to be incorporated into stable trimers or disturb type X collagen assembly.

Base Sequence↗
PubMed1994

Mutations in the gene encoding fibroblast growth factor receptor-3 in achondroplasia.

Achondroplasia, the most common cause of chondrodysplasia in man (1 in 15,000 live births), is a condition of unknown origin characterized by short-limbed dwarfism and macrocephaly. More than 90% of cases are sporadic and there is an increased paternal age at the time of conception of affected individuals, suggesting that de novo mutations are of paternal origin. Affected individuals are fertile and achondroplasia is transmitted as a fully penetrant autosomal dominant trait, accounting for rare familial forms of the disease (10%). In contrast, homozygous achondroplasia is usually lethal in the neonatal period and affects 25% of the offspring of matings between heterozygous achondroplasia parents. The gene responsible for achondroplasia has been mapped to chromosome 4p16.3 (refs 7, 8); the genetic interval encompassing the disease gene contains a member of the fibroblast-growth-factor receptor (FGFR3) family which is expressed in articular chondrocytes. Here we report the finding of recurrent missense mutations in a CpG doublet of the transmembrane domain of the FGFR3 protein (glycine substituted with arginine at residue 380, G380R) in 17 sporadic cases and 6 unrelated familial forms of achondroplasia. We show that the mutant genotype segregates with the disease in these families. Thus it appears that recurrent mutations of a single amino acid in the transmembrane domain of the FGFR3 protein account for all cases (23/23) of achondroplasia in our series.

Achondroplasia↗
PubMed1994

Mutation in the COL2A1 gene in a patient with hypochondrogenesis. Expression of mutated COL2A1 gene is accompanied by expression of genes for type I procollagen in chondrocytes.

A new dominant mutation in the COL2A1 gene was found in a 38-week-old fetus with hypochondrogenesis. Denaturing gradient gel electrophoresis was used to analyze all 44 exons coding for the triple-helical domain of COL2A1 gene and the corresponding exon-intron boundaries. The technique detected a new sequence variation in exon 35. Sequencing of exon 35 demonstrated a single base mutation that converted the codon for glycine at position 604 to a codon for alanine. Electrophoresis of pepsin-digested collagen extracted from the diseased cartilage showed a doublet band of the alpha 1(II) chain of type II collagen and the presence of alpha 1(I) and alpha 2(I) chains of type I collagen. Two-dimensional analysis of cyanogen bromide peptides from the type II collagen revealed post-translational overmodification of peptides CB12, CB11, CB8, and CB10.5, whereas peptide CB9.7 migrated normally. Microscopic examination of cartilage showed that the mutation altered the organization of the growth plate. Also, articular chondrocytes contained large cisternae of rough endoplasmic reticulum. The density of the extracellular matrix was reduced, and the intensity of the staining with an antibody to type II collagen was diminished. In contrast, a significant staining with an antibody to type I collagen was observed. In situ hybridization with cRNA probes revealed a significant level of alpha 1(I) mRNA in the cytoplasm of the patient's chondrocytes. The signal for alpha 1(II) mRNA was about the same in control samples. The results indicated, therefore, that the genes for both type I and type II procollagens were simultaneously expressed in chondrocytes from the patient.

Adult↗
PubMed1994

Achondrogenesis type IB (Fraccaro): study of collagen in the tissue and in chondrocytes cultured in agarose.

A lethal chondrodysplasia characterized by extreme micromelia was diagnosed by ultrasound examination in two sibs whose nonconsanguineous parents were healthy. Radiographic and histopathologic data indicated that the two foetuses (18 and 21 weeks old) had achondrogenesis type IB (Fraccaro). Quantitation of total collagen extractable from dried cartilage samples demonstrated a 50% decrease when compared to an age-related control. This decrease was essentially related to type II collagen. Nevertheless, the alpha chains and the CB peptides of type II collagen had a normal electrophoretic mobility. A significant amount of collagen type I was also detected. The electrophoretic pattern of collagens type IX and XI did not differ significantly from control sample. The extracellular matrix elaborated by patient chondrocytes cultured in agarose for 10-12 days, contained less collagen type II than normal cells. Labelling with 14C-proline of cultured cells showed the presence of procollagen and type II collagen chains with a normal electrophoretic mobility, but an alpha 2(I) chain was detectable in the patient material, indicating the presence of collagen type I which supported the tissue findings. The significance of the type II collagen reduction in the patient's cartilage is unclear but it is unlikely to be the primary defect in achondrogenesis type I.

Blotting, Western↗
PubMed1994

Reexpression of cartilage-specific genes by dedifferentiated human articular chondrocytes cultured in alginate beads.

We have used the three-dimensional culture system in alginate beads to redifferentiate human articular chondrocytes which were first expanded on a plastic support. After 15 days in alginate beads, electron microscopy showed that cells had synthesized an extracellular matrix containing collagen fibrils. Electrophoretic analysis of proline-labeled cells demonstrated that redifferentiated chondrocytes synthesized mainly type II collagen and its precursors (pro alpha 1II, pc alpha 1II, and pn alpha 1II). After pepsin digestion a small amount of collagen type XI was also detected. These results were confirmed by Northern blot analysis of total RNAs. Hybridization with collagen cDNA probes coding for the alpha 1(II) and alpha 1(I) chains of collagen types II and I showed that chondrocytes cultured in alginate expressed mainly alpha 1(II) mRNA, whereas alpha 1(I) mRNA transcripts were almost undetectable. Such a result was observed even after several passages on plastic flasks, suggesting that dedifferentiated cells were able to revert to a chondrocytic phenotype in this three-dimensional system. However, SV40-transformed chondrocytes were not able to redifferentiate in alginate as no alpha 1(II) mRNAs were detected. Total RNA was converted into cDNA by reverse transcription and amplified by polymerase chain reaction. This technique was employed to amplify mRNAs specific for collagen type II and type X and the large aggregating proteoglycan aggrecan. Two transcripts resulting from an alternative splicing of the complement regulatory protein (CRP)-like domain of aggrecan were originally identified in chondrocytes in monolayers. Like intact cartilage, chondrocytes in alginate expressed only the larger transcript with the CRP domain, whereas the two transcripts were equally expressed in SV40-transformed chondrocytes. Thus, the alginate system appears to represent a relevant model for the redifferentiation of human chondrocytes, especially when only a small cartilage biopsy is available, and could prove useful for pulse-chase studies of patients with skeletal chondrodysplasias. However it was unable to restore the chondrocytic phenotype in virally transformed cells.

Alginates↗
PubMed1994

Localization of the expression of type I, II and III collagen genes in human normal and hypochondrogenesis cartilage canals.

The expression of type I, II and III collagens genes was examined in human normal and hypochondrogenesis cartilage canals employing electrophoretic analysis, immunohistochemistry and in situ hybridization techniques. In normal cartilage, collagens type I and III were present in perichondrium, in the connective tissue surrounding the vessels of cartilage canals and in the dense fibrous tissue. However, types I and III procollagen mRNAs were detected only in fibroblasts of the perichondrium and of the canals, but not in the polymorphic cells. Type II collagen was present in the cartilage matrix and in the dense fibrous tissue, in good accordance with the localization of type II procollagen mRNAs detected in the chondrocytes and in the polymorphic cells. These data suggest that there are no transitional cells expressing type I, II and III collagen genes and that polymorphic cells are of chondrocytic origin. In the case of hypochondrogenesis, type II collagen was less abundant than in normal cartilage, whereas the corresponding mRNA level was equivalent. That suggests that a postranscriptional regulation of this protein is involved in the decrease of type II collagen production. Type I collagen, unexpectedly detected in the cartilage matrix, was synthesized by chondrocytes and polymorphic cells, suggesting a replacement of type II by type I collagen. The canal hypertrophy observed in this pathological case could thus be due to a modification in the regulation of the growth of cartilage canals caused by a defective cartilage matrix.

Cartilage↗
PubMed1994

A gene for achondroplasia-hypochondroplasia maps to chromosome 4p.

Achondroplasia (ACH) is a frequent condition of unknown origin characterized by short-limbed dwarfism and macrocephaly. Milder forms, termed hypochondroplasias (HCH) result in short stature with radiological features similar to those observed in ACH. We report on the mapping of a gene causing ACH/HCH to human chromosome 4p16.3, by linkage to the iduronidase A (IDUA) locus, in 15 informative families (Z max = 3.01 at theta = 0 for ACH; Z max = 4.71 at theta = 0 for ACH/HCH). Multipoint linkage analysis provides evidence for mapping the disease locus telomeric to D4S412 (location score in log 10 = 4.60). Moreover, this study supports the view that ACH and HCH are genetically homogeneous in our series.

Achondroplasia↗
PubMed1992

Type II collagen defect in two sibs with the Goldblatt syndrome, a chondrodysplasia with dentinogenesis imperfecta, and joint laxity.

We report on a syndrome of spondylo-epimetaphyseal dysplasia, dentinogenesis imperfecta, and ligamentous hyperextensibility in two sibs born to nonconsanguineous parents. This chondrodysplasia was characterized by severe shortness of stature and an osteoporosis without fractures. Electron microscopic examination of the cartilage documented large vacuoles of dilated rough endoplasmic reticulum within the cytoplasm of chondrocytes. Gel electrophoresis of pepsin-soluble collagen extracted from cartilage demonstrated the presence of type II collagen chains with an abnormal mobility. Prolyl and lysyl hydroxylations were slightly increased. The abnormal molecules melted at a higher temperature than the normal ones. CNBr peptide mapping of type II collagen showed an altered electrophoretic migration of peptides CB 11, CB 8, and CB 10,5 whereas CB 9,7 looked normal. In addition, two small non-collagenous proteins isolated from cartilage were not found in an age-matched control individual but were detected in a normal newborn infant. The quantitation of proline-labelled collagen synthesized by dermal fibroblasts demonstrated a 50% reduction of total collagen. This decrease essentially affected the amount of extracellular type I collagen, which was secreted less efficiently than in control cells. Nevertheless, type I collagen chains behaved normally on 5% polyacrylamide gels. The reduced mRNA levels of alpha 1I and alpha 2I chains might reflect either a transcriptional defect or a decreased stability of mRNA transcripts. We suggest that the association of both pathological chondrocytes producing altered collagen type II and decreased synthesis of type I could be responsible for this peculiar phenotype. The overmodification of alpha 1II CNBr peptides is consistent with the presence of a single-base substitution in the COL2A1 gene. Whether there is a direct causal relationship between the type II collagen defect and the underexpression of type I collagen will require clarification.

Abnormalities, Multiple↗
PubMed1992

Transforming growth factor-beta 1 (TGF-beta 1) up-regulation of collagen type II in primary cultures of rabbit articular chondrocytes (RAC) involves increased mRNA levels without affecting mRNA stability and procollagen processing.

The effect of transforming growth factor-beta 1 (TGF-beta 1) on collagen biosynthesis was investigated in confluent primary monolayer cultures of rabbit articular chondrocytes (RAC). Exposure to TGF-beta (0.1, 1, and 10 ng/ml) in serum-free medium caused a dose- and time-dependent stimulation of collagen biosynthesis associated with an increase of steady-state levels of procollagen type II mRNA. Elevation of the mRNA steady-state did not result from a stabilization of the transcript, as shown by measure of the mRNA half-life. Electrophoresis (SDS-PAGE) showed that TGF-beta stimulates the synthesis of most collagen isotypes, including type II, without qualitative change in their distribution. Moreover, pulse-chase experiments revealed that TGF-beta did not affect the processing rate of type II procollagen. TGF-beta slightly stimulated the production of prostaglandin E2 (PGE2), which could in turn exert an inhibition on collagen synthesis. However, addition of indomethacin to block prostaglandin synthesis did not further enhance the TGF-beta-induced stimulation of collagen production, suggesting that this mediator was not implicated in the effect. Moreover, TGF-beta increased steady-state levels of procollagen type II, I, and III mRNAs even in the presence of indomethacin. Despite these increased mRNA levels, only the production of type II collagen was significantly augmented, suggesting that type I procollagen mRNA was not fully translated. In addition, the TGF-beta-induced stimulation of collagen synthesis was observed whenever ascorbic acid is added or not in the culture medium. In conclusion, TGF-beta, which is present in great amount in bone and cartilage, can increase the collagen production of cultured RAC and might therefore play a role in the early events of cartilage repair, such as those observed in osteoarthritis.

Animals↗