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Biomedical subjects

M Goossens

Publications and source records attributed to M Goossens.

At least 127 records · Page 7Linked to original sources
PubMed1993

A naturally occurring growth hormone receptor mutation: in vivo and in vitro evidence for the functional importance of the WS motif common to all members of the cytokine receptor superfamily.

To obtain an animal model for studying the role of the GH receptor (GHR) in growth and development, we analyzed a sex-linked dwarf (SLD) chicken strain (Leghorn) which exhibits phenotype similarities with a human genetic growth disorder, an autosomal recessive GH resistance condition (Laron dwarfism). Having previously demonstrated the responsibility of the human GHR gene in the Laron phenotype, we focused our analysis on the corresponding gene in SLD chickens. Sequencing of the whole coding region of the chicken GHR cDNA identified a G-to-T transversion segregating with the SLD phenotype and generating an isoleucine instead of a serine at position 199 within a highly conserved region close to the junction between the extracellular and transmembrane domains. This defect involves the last invariant amino acid of the WS-like motif (amino acid sequence WSXWS) common to all members of the cytokine receptor superfamily. Transfection of a mutated GHR cDNA containing this mutation into eukaryotic cells led to the synthesis of a receptor protein that displayed impaired plasma membrane expression and binding activity. These data define the molecular basis for the SLD phenotype and identify this strain as an interesting model for studying Laron dwarfism in humans; this animal model may also represent a system in which therapeutic strategies to promote growth can be evaluated. Finally, the nature of the molecular defect identified provides direct evidence for the functional importance of the WS motif in GHRs and related receptors.

Amino Acid Sequence↗
PubMed1993

[The cystic fibrosis gene, its product CFTR protein and its mutations].

Cystic fibrosis (CF) is a fatal genetic disease primarily affecting Caucasians. Its etiology is complex, but it is chiefly a disease of electrolyte transport characterized by defects in fluid secretion by several epithelia. In this review are analyzed the data obtained since the cloning of the CF gene and the characterization of its product, the CF transmembrane conductance regulator (CFTR) protein, which has been shown to act like a cAMP-regulated chloride channel. This protein is a member of a family of ATP-binding proteins that are membrane-spanning, are found in a number of prokaryotic and eucaryotic cells, and have two ATP-binding domains. Unique to this family of proteins, the CFTR possesses an additional highly charged domain (the R domain). The majority of CF chromosomes (70%) have a single Phenylalanine codon deletion at position 508 of the protein (delta F508). A large number of other rare mutations (more than 230) have also been identified. This rapid accumulation of data is essential to genetic diagnosis and will aid in understanding the structure and function of the protein.

Cystic Fibrosis↗
PubMed1992

A comprehensive scanning method for rapid detection of beta-globin gene mutations and polymorphisms.

We describe a scanning procedure for the detection of beta-globin gene mutations and the prenatal diagnosis of beta-thalassemias. The method is based on the combined use of PCR and denaturing gradient gel electrophoresis (DGGE) of six amplified fragments encompassing the whole beta-globin coding region and splice junctions, as well as the promoter and 3' untranslated regions. The whole beta-globin gene can be rapidly scanned for the presence of deleterious mutations. The proposed diagnostic strategy provides a major improvement over current approaches to beta-globin gene analysis in both research and clinical laboratories, especially those which analyse DNA samples from individuals belonging to various ethnic or population groups. The use of this procedure has enabled us to detect six novel sequence changes in the beta-globin gene, including two deleterious mutations and four polymorphisms.

Base Sequence↗
PubMed1992

Two novel mutations responsible for hereditary type I protein C deficiency: characterization by denaturing gradient gel electrophoresis.

Hereditary protein C (PC) deficiency is usually associated with a high risk of thrombosis. We report the results of a study undertaken to screen for molecular defects in families with hereditary quantitative PC deficiency. Using a strategy combining polymerase chain reaction amplification of selected gene fragments, denaturing gradient gel electrophoresis of the amplification products, and direct sequencing of fragments with altered melting behavior, we studied the PC gene exons and exon/intron junctions of subjects with hereditary type I PC deficiency. Computer simulation of DNA melting was used to design several sets of primers, each containing a GC-clamp, permitting the complete analysis of each amplified exon sequence. Using this procedure, we identified two previously undescribed mutations located in exon VII: a C-to-T substitution generating a nonsense codon in place of Arg 157 in the mature PC and a G-to-A substitution converting Arg 178 to GIn. The two mutations were detected in, respectively, 3 and 2 apparently independent families. This strategy is therefore a valuable tool for screening patients, and the results emphasize its advantages over plasma assays in individuals with a family history of thrombosis.

Adult↗
PubMed1992

Rapid molecular characterization of mutations leading to unstable hemoglobin beta-chain variants.

Characterization of unstable hemoglobins by protein analysis is often difficult. However, it is facilitated by DNA analysis, especially in the case of hyperunstable beta-chain variants, which produce a beta-thalassemia phenotype. We have applied an efficient strategy to the detection of such variants at the DNA level, based on computer-designed denaturing gradient gel electrophoresis (DGGE) of amplified DNA fragments. This approach makes it possible to detect any anomaly in the beta-globin gene. We describe the use of the DGGE method for rapid characterization of beta-chain variants and report a new missense mutation in the beta-globin gene third exon, beta 127 CAG-CGG/Gln-Arg, which is responsible for the synthesis of a highly unstable hemoglobin.

Adolescent↗
PubMed1992

Molecular characterization of cystic fibrosis: 16 novel mutations identified by analysis of the whole cystic fibrosis conductance transmembrane regulator (CFTR) coding regions and splice site junctions.

The spectrum of cystic fibrosis (CF) mutations was determined in 105 patients by using denaturing gradient gel electrophoresis to screen the entire coding regions and adjacent cystic fibrosis transmembrane conductance regulator (CFTR) gene sequences. The nucleotide substitutions detected included 16 novel mutations, 11 previously described defects, and 11 nucleotide sequence polymorphisms. Among the novel mutations, 6 were of the missense type, 4 were nonsense mutations, 4 were frameshift defects, and 2 affected mRNA splicing. The mutations involved all the CFTR domains, including the R domain. Of the 61 non-delta F508 CF chromosomes studied, mutations were found on 36 (59%), raising the proportion of CF alleles characterized in our patient cohort to 88%. Given the efficacy of the screening method used, the remaining uncharacterized mutations probably lie in DNA sequences outside the regions studied, e.g., upstream-promoter sequences, the large introns, or putative regulatory regions. Our results further document the highly heterogeneous nature of CF mutations and provide the information required for DNA-based genetic testing.

Base Sequence↗
PubMed1992

Exhaustive screening of exon 10 CFTR gene mutations and polymorphisms by denaturing gradient gel electrophoresis: applications to genetic counselling in cystic fibrosis.

Several mutations in the cystic fibrosis (CF) gene have been reported. Ten, including the most prevalent mutation in Caucasians, delta F508, are located in exon 10 of the gene, in addition to five sequence polymorphisms. We have previously presented a strategy based on denaturing gradient gel analysis for the rapid detection of any nucleotide variation in all the exons and their immediate flanking regions. We now report the application of this method to the simultaneous detection of all mutations and polymorphisms located in exon 10, together with the use of exon 10 polymorphisms, especially the most frequent one (M470V), as intragenic markers for prenatal diagnosis of cystic fibrosis in families with at least one affected child and unknown disease-causing mutations.

Base Sequence↗
PubMed1992

Symbolic play development in toddlers with expressive specific language impairment (SLI-E).

Twenty toddlers with expressive specific language impairment (SLI-E) and 20 toddlers with normal language development were compared in their symbolic play development. The groups did not differ in amount of engagement with the toys or in functional conventional play behaviors. However, the children with SLI-E displayed less decentered play (use of play schemes with a doll or another person), less well-developed sequential play, and fewer occurrences of symbolic play transformations (use of a neutral object or an absent object to carry out pretending). The provision of structure in the form of thematically related toy sets, instructions, and modeling did not reduce the discrepancy between demonstrated play behaviors of toddlers with SLI-E and their normally developing peers. Three possible explanations for this discrepancy are considered: a "stylistic" difference in play, a developmental lag in symbol use, or a deficit in retrieval of stored symbolic representation.

Child Behavior↗
PubMed1992

Genetic linkage of recessive dystrophic epidermolysis bullosa to the type VII collagen gene.

Generalized mutilating recessive dystrophic epidermolysis bullosa (RDEB) is characterized by extreme skin fragility owing to loss of dermal-epidermal adherence. Immunohistochemical studies have implicated type VII collagen, the major component of anchoring fibrils, in the etiology of RDEB. In this study, we demonstrate genetic linkage of the type VII collagen gene and the generalized mutilating RDEB phenotype. We first identified a Pvull polymorphic site by digestion of an amplified product of the type VII collagen gene, which was shown to reside within the coding region. Genetic linkage analysis between this marker and the RDEB phenotype in 19 affected families which were informative for this polymorphism showed no recombination events, and gave a maximum lod score of 3.97 at a recombination fraction (theta) of 0, demonstrating that this DNA region is involved in this form of RDEB. These data provide strong evidence that the type VII collagen gene, which has also been linked with the dominant form of the disease, harbors the mutation(s) causing the generalized mutilating form of RDEB in these families, thus underscoring the major functional importance of type VII collagen in basement membrane zone stability.

Base Sequence↗
PubMed1992

[Molecular genetics of growth hormone resistance syndrome].

The cloning of a putative growth hormone receptor (GH-R) cDNA has opened new approaches for the understanding of the molecular basis of GH insensitivity in humans. This molecule belongs to a new class of transmembrane receptors including prolactin, granulocyte-macrophage colony stimulating factor, erythropoietin and some interleukin receptors. Although the domains responsible for signal transduction have not yet been identified, the molecular study of a GH-resistance syndrome described by Laron et al. should provide insight into the structure-function relationships of the GH-R and related receptors. This autosomal recessive disorder is characterized by very low serum levels of Insulin-Like Growth Factor I (IGF-I), despite increased secretion of GH with normal activity. Two approaches can be used to test the involvement of the GH-R in this syndrome. The first one, which is indirect, is performed through linkage analysis between GH-R and Laron phenotype; this allowed us to incriminate the GR-R gene in this syndrome. The second approach consists in the identification of molecular defects in the GH-R gene of patients with Laron syndrome; this allowed the detection of a partial gene deletion and different point mutations. The short stature of the Pygmee population could be related to the Laron syndrome because individuals from this population are also resistant to GH therapy. Therefore, it seems interesting to search for molecular variations of the GH-R gene in this population. Nevertheless, preliminary results indicate that the GH-R gene is not directly involved in this particular short stature condition.(ABSTRACT TRUNCATED AT 250 WORDS)

Black People↗