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Biomedical subjects

D Bonneau

Publications and source records attributed to D Bonneau.

At least 19 recordsLinked to original sources
PubMed1997

[Tissue expression of a gene potentially implicated in some diseases with retinal and renal involvement].

We have produced a monoclonal antibody (HA34) that specifically reveals the pigmented epithelium in the eye and the proximal convoluted tubules of the kidney, whatever the developmental stage. The results obtained with the kidney of other mammals suggest that the antigen is human specific. Its molecular weight is approximately 200 kDa. The epitope recognized by HA34 is always present on cell lines grown in vitro. This allowed us to use somatic cell interspecific hybrids to localize the gene implicated in the cytogenetic band 11q13, between microsatellites D11S1777 (AFMa046wa9) and D11S913 (AFM164zf12) in a 9 cM space. This region is involved in forms of retinitis pigmentosa, some of which can also include kidney abnormalities. We propose that this gene is possibly implicated in some of these diseases.

Animals↗
PubMed1997

Administration of a GABAB agonist baclofen before running to exhaustion in the rat: effects on performance and on some indicators of fatigue.

The present study was designed to examine the effects of administration of a GABAergic agonist (Baclofen) on run-time to exhaustion in trained and untrained rats, and on some indicators of fatigue. Run-time to exhaustion on a treadmill set at a speed of 25 m.min-1 was significantly increased in both untrained (p < 0.01) and trained rats (p < 0.005) administered with baclofen one hour before the exercise. The animals who had run the longest time displayed the lowest concentrations of liver and muscle glycogen, and a decrease in plasma glucose concentrations (p < 0.05). The results of this investigation suggest that fatigue during prolonged exercise can be influenced by pharmacological administration of a GABAergic agonist. Indicators of fatigue such as glycemia, liver and muscular glycogen are not the limiting factors of performance and central mechanisms play a key role at exhaustion.

Analysis of Variance↗
PubMed1996

Abnormal cholesterol biosynthesis in the Smith-Lemli-Opitz and the lethal acrodysgenital syndromes.

UNLABELLED: The Smith-Lemli-Opitz syndrome (SLO) is an autosomal recessive disorder characterized by dysmorphic facial features with abnormal limbs and genitalia. Two forms have been recognized based on clinical course and severity: the classical SLO (type I) and the lethal acrodysgenital syndrome (type II). Type I SLO has been recently ascribed to a defect in cholesterol synthesis. Taking advantage of a series of seven patients including five type I and two type II SLO, we describe micrognathia, severe microcephaly, major ante and post natal growth retardation and feeding difficulties as consistent features in the disease. In addition, we give support to the presence of abnormal cholesterol levels in the lethal acrodysgenital syndrome but find no correlation between plasma sterol levels and the clinical severity of the disease. CONCLUSION: The identification of the same biochemical defect in both types of Smith-Lemli-Opitz Syndrome suggests that despite major discrepancies in clinical course and severity, type I and type II SLo are probably allelic disorders.

Child↗
PubMed1996

Increased paternal age in CHARGE association.

The acronym CHARGE refers to a non-random clustering of congenital malformations whose cause remains unknown. Here, we report on a series of 41 patients and find a significant increase in mean paternal age of birth of CHARGE patients (33.7 +/- 8 years) compared with the control population (30.8 +/- 5 years). In contrast, maternal age was not statistically different in patients and controls. These data suggest the possible role of a dominant mutation or, less likely, a subtle chromosomal abnormality in CHARGE association.

Abnormalities, Multiple↗
PubMed1996

Evidence for a fourth locus in Usher syndrome type I.

Usher syndrome type I (US1) is an autosomal recessive condition in which three different genes have been already localised (USH1A, USH1B, and USH1C on chromosomes 14q32, 11q13, and 11p15 respectively). The genetic heterogeneity of US1 has been confirmed in a previous study by linkage analysis of 20 French pedigrees. Here, we report the genetic exclusion of the three previously reported loci in two large multiplex families of Moroccan and Pakistani origin, suggesting the existence of at least a fourth locus in Usher syndrome type I.

Abnormalities, Multiple↗
PubMed1995

A gene for blepharophimosis-ptosis-epicanthus inversus syndrome maps to chromosome 3q23.

Blepharophimosis-ptosis-epicanthus inversus syndrome (BPES) is an autosomal dominant malformation of the eyelids that may severely impair visual function. Chromosomal aberrations involving chromosomes 3q23, 3p25 and 7p34 have been reported in BPES but the disease gene has not been hitherto localized by linkage analysis. We have mapped a gene for BPES to chromosome 3q23 in a large French pedigree (Zmax = 4.62 at Theta = 0 for probe AFM 182yc5 at locus D3S1549). The best estimate for the location of the disease gene is at locus D3S1549, between the loci D3S1292 and D3S1555 (maximum lod score of 5.10).

Abnormalities, Multiple↗
PubMed1995

Exclusion of the cone-specific alpha-subunit of the transducin gene in Stargardt's disease.

Stargardt's disease is an autosomal recessive infantile macular degeneration of unknown origin whose gene has been recently mapped to chromosome 1p21-p13 by linkage analysis in eight multiplex families. Since the cone-specific alpha-subunit of the transducin gene (GNAT2) has been mapped to chromosome 1p13, we tested GNAT2 as the disease-causing gene in our series. Using a novel intragenic polymorphism, we show here that GNAT2 is most probably located centromeric to the genetic interval encompassing the disease gene (D1S424-D1S236, location score = 3.54). In addition, single-strand conformation polymorphism and sequence analyses of the eight exons of the GNAT2 gene was performed in our probands. No evidence of a deleterious base substitution was observed in any affected individual. Taken together, these results support the exclusion of GNAT2 as the causal disease gene of Stargardt's disease. come. The pathogenesis is unknown and the treatment is limited to ultraviolet ray protection with dark glasses. Stargardt's disease has been recently mapped to chromosome 1p21-p13 in the genetic interval defined by loci D1S424 and D1S236. In addition, our previous study has suggested that Stargardt's disease is genetically homogeneous (Kaplan et al. 1993). With respect to the physical mapping of the proteins specific to the retinal pigmentary epithelium or to cones we noted that the cone-specific alpha-subunit of the transducin gene (GNAT2) has been mapped to chromosome 1p13 (Wilkie et al. 1992). The human GNAT2 is 9967 bp in length and consists of eight exons with seven introns (Morris and Fong 1993). In the present study, we examined this gene as the candidate gene in eighteen unrelated patients affected with Stargardt's disease.

Base Sequence↗
PubMed1995

[Hyperexplexia].

Hyperexplexia is a disease of neonatal onset characterized by an exaggerated startle reflex. Early diagnosis is important to rule out epilepsy. Clinical findings are mainly hypertony and generalized startle reflex which is exaggerated by tiredness and some exogenous stimuli. Electroencephalogram is normal. The expression of the disease is variable including minor forms that may be unnoticed and major forms with arthrogryposis-like symptoms, orthopedic complications, false passages, apnea and even sudden infant death (SID). The evolution is generally benign and symptoms disappear within 2 or 3 years. A neuromotor retardation is often present, without intellectual deficit. In severe forms, the risk of SID requires a multidisciplinary follow-up including monitoring and treatment with clonazepam. A low GABA level in cerebrospinal fluid has been reported. Present etiological hypotheses include neuromediator and/or receptor dysfunction.

Humans↗
PubMed1995

Mutation in the iron responsive element of the L ferritin mRNA in a family with dominant hyperferritinaemia and cataract.

The synthesis of ferritin, the iron-storing molecule, is regulated at the translational level by iron through interaction between a cytoplasmic protein, iron regulatory protein (IRP), and a conserved nucleotide motif present in the 5' non-coding region of all ferritin mRNAs--the iron responsive element (IRE). This region forms a stem-loop structure and when the supply of iron to the cells is limited, the IRP is bound to IRE and represses ferritin synthesis. Ferritin is composed of a 24-subunit protein shell surrounding an iron core. The two types of subunit, H and L, are encoded by two genes located on chromosomes 11q13 and 19q13.1, respectively. Both genes are ubiquitously expressed but transcriptional regulation mediates tissue-specific changes in the H/L mRNA ratio and isoferritin profiles. We now report the identification of a single point mutation in the IRE of the L-ferritin mRNA in members from a family affected with dominantly inherited hyperferritinaemia and cataract. This mutation consists of an A to G change in the highly conserved CAGUGU motif that constitutes the IRE loop and mediates the high-affinity interaction with the IRP. We show that this mutation abolishes the binding of IRP in vitro and leads to a high constitutive, poorly regulated L-ferritin synthesis in cultured lymphoblastoid cells established from affected patients. This is, to our knowledge, the first mutation affecting the IRP-IRE interaction and the iron-mediated regulation of ferritin synthesis. We suggest that excess production of ferritin in tissues is responsible for the hyperferritinaemia and that intracellular accumulation of ferritin leads to cataract.

Base Sequence↗
PubMed1995

A gene for Leber's congenital amaurosis maps to chromosome 17p.

Leber's congenital amaurosis (LCA) is an autosomal recessive disease responsible for congenital blindness. It is the most early and severe form of inherited retinopathy and accounts for 5% of all inherited retinal dystrophies. Here we report the first mapping of a gene for LCA to the distal short arm of chromosome 17 by linkage analysis in 15 multiplex families (Zmax = 5.14 at theta = 0.15 for probe AFM070xg5 at the D17S1353 locus). When our sample was split into two groups according to the ethnic origin of the patients we were able to confirm the presence of a gene for LCA on chromosome 17p by both homozygosity mapping and linkage analysis in five families of Maghrebian origin (LCA1, Zmax = 7.21 at theta = 0.01 at the D17S1353 locus), while negative results were found in 10 families of French ancestry. Haplotype analyses supported the placement of LCA1 between loci D17S796 and D17S786 (maximum likelihood estimate for location of the disease gene over the D17S1353 locus). The genetic heterogeneity of LCA will complicate the prenatal detection of this frequent cause of congenital blindness.

Blindness↗
PubMed1995

No evidence of genetic heterogeneity in dominant optic atrophy.

Autosomal dominant optic atrophy (OPA, MIM 165500) is an eye disease causing a variable reduction of visual acuity with an insidious onset in the first six years of life. It is associated with a central scotoma and an acquired blue-yellow dyschromatopsia. A gene for dominant optic atrophy (OPA1) has recently been mapped to chromosome 3q in three large Danish pedigrees. Here, we confirm the mapping of OPA1 to chromosome 3q28-qter by showing close linkage of the disease locus to three recently reported microsatellite DNA markers in the interval defined by loci D3S1314 and D3S1265 in four French families (Zmax = 5.13 at theta = 0 for probe AFM 308yf1 at locus D3S1601). Multipoint analysis supports the mapping of the disease gene to the genetic interval defined by loci D3S1314 and D3S1265. The present study provides three new markers closely linked to the disease gene for future genetic studies in OPA.

Chromosome Mapping↗