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Biomedical subjects

F Munier

Publications and source records attributed to F Munier.

At least 19 recordsLinked to original sources

Diagnosis and current management of retinoblastoma.

Retinoblastoma represents the prototypic model for inherited cancers. The RB1 gene was the first tumor suppressor gene to be identified. It represents the most frequent primary eye cancer in children under 15 years old, habitually occurring in infancy, even in utero, but can be observed in older children or young adults. Many other retinal lesions may also simulate retinoblastoma. The two major presenting signs are leukocoria and strabismus, but other ocular or general signs may be observed. A highly malignant tumor, retinoblastoma can nowadays be cured. The heritable form, however, carries a high risk of second nonocular tumors. Treatment in the early stages of disease holds a good prognosis for survival and salvage of visual function. In very late stages, however, the prognosis for ocular function and even survival is jeopardized.

Cell Division↗

Evanescent white linear flecks and posterior microphthalmos: new features of a recently established disease.

BACKGROUND: Posterior microphthalmos is a rare autosomal recessive condition with normal anterior segment and small posterior segment resulting in axial hyperopia and retinal folding. HISTORY AND SIGNS: The proband from a consanguineous Turkish family was clinically investigated at 5 months of age and followed for the next 8 years. At five months of age, refraction revealed a severe hyperopia of + 10 diopters in both eyes (OU) with a mean axial length of 16.5 mm. Fundus examination showed a dystrophic maculo-papillar bundle. Multiple whitish deep intraretinal linear lesions sparing the macula were present in the mid-periphery with no preferential orientation. THERAPY AND OUTCOME: By 8 years of age, visual acuity was 20/25 in the right eye (OD) and 20/30 in the left eye (OS) with S + 14 OU. The whitish linear lesions had disappeared and were replaced by retinal pigment epithelium alterations. Optical coherence tomography (OCT) revealed a thickened retina with normal appearance at the site of the linear lesions. CONCLUSIONS: This is the first report of long-term follow-up and OCT findings in this rare ocular developmental abnormality.

Child↗

Pseudoxanthoma elasticum: evaluation of diagnostic criteria based on molecular data.

BACKGROUND: Pseudoxanthoma elasticum (PXE) is a genetic disorder due to mutations in the gene encoding the transmembrane transporter protein adenosine triphosphate binding cassette (ABC)-C6, resulting in calcification of elastic fibres in the skin, eyes and cardiovascular system. OBJECTIVES: To evaluate the diagnostic criteria for PXE based on molecular data. METHODS: Of 10 families with a positive history of PXE 142 subjects were investigated for clinical symptoms, histological findings and genetic haplotype analysis. RESULTS: Of these, 25 subjects were haplotypic homozygous for PXE and 23 had typical clinical and histopathological manifestations. Two of the 25 patients showed such marked solar elastosis and macular degeneration that PXE could not be confirmed clinically. Sixty-seven subjects were haplotypic heterozygous carriers and 50 were haplotypic homozygous unaffected. Of these 117 subjects, 116 showed no cutaneous or ophthalmological signs of PXE. In one of the 50 haplotypic homozygous unaffected patients important solar elastosis and scarring of the retina mimicked PXE lesions. Only four of the 67 haplotypic heterozygous carriers had biopsies of nonlesional skin; all were histopathologically normal. CONCLUSIONS: In our patients, PXE presents as an autosomal recessive genodermatosis. Correlation of haplotype and phenotype confirmed actual major diagnostic criteria. In patients with marked solar elastosis and/or severe macular degeneration clinical diagnosis can be impossible and molecular testing is needed to confirm the presence of PXE. To the best of our knowledge our large study compares for the first time clinical findings with molecular data.

ATP-Binding Cassette Transporters↗

Pulverulent cataract with variably associated microcornea and iris coloboma in a MAF mutation family.

AIMS: To report the detailed clinical findings in a three generation pedigree with autosomal dominant cataract, microcornea, and coloboma resulting from mutation of the lens development gene, MAF. METHODS: Five members of a three generation pedigree with progressive cataracts underwent detailed ophthalmic examination to characterise associated ocular phenotypic features. RESULTS: The cataracts present in all affected individuals were cortical, and/or nuclear, pulverulent opacities. Corneal diameters of 10-10.25 mm were present in two family members. Axial lengths were in the normal range. Bilateral iris coloboma in the 6 o'clock position was present in one patient. Uveal melanoma was present in one patient, with uveal naevi in this and one other patient. CONCLUSION: The bZIP transcription factor MAF is a key lens development gene that regulates the expression of the crystallins. Individuals with a mutation in MAF may have pulverulent cataract alone or cataract in association with microcornea or iris coloboma.

Adolescent↗

[Centenary of the first radiotherapy treatment of retinoblastoma (Hilgartner, 1903)].

One hundred years ago, Hilgartner used external radiotherapy for the first time in the treatment of retinoblastoma. This first case was published in the Texas Medical Journal in 1903. Immediate results were reported to be excellent but the long-term outcome was not known. The first documented cure of retinoblastoma over a long period of time was a case initially treated by Verhoeff (Boston) in 1917, with histopathological findings provided 71 years later by Marcus et al. at the patient's death. Henry Louis Hilgartner was born in 1868 in Baltimore and died in 1937 at the age of 69. His revolutionary treatment developed from the discovery of X-rays in 1895 by Wilhelm Conrad Röntgen and the parallel discovery of radioactivity by Henri Bequerel and Marie and Pierre Curie. In the sociopolitical context of 1903, Emile Loubet was president of France and this same year saw the Wright brothers' first motorized flight with the first power-driven heavier-than-air machine. The development of radiotherapy in the treatment of retinoblastoma can be divided into three distinct periods: an initial period of trial and error lasting from 1903 to 1928; a second period from 1929 to 1948 covering the introduction of calibrated radon needles up to the advent of external radiotherapy, and a third period, from 1948 to the present day, which can be considered a time of technical improvement and innovation. One hundred years ago, radiotherapy made a triumphant entry on the scene of retinoblastoma management. With our present knowledge of its side effects, we are now trying to remove it.

Baltimore↗

Use of denaturing HPLC and automated sequencing to screen the VMD2 gene for mutations associated with Best's vitelliform macular dystrophy.

We identified three novel VMD2 mutations in patients with Best's macular dystrophy. DHPLC analysis of the 11 VMD2 exons revealed abnormal profiles in exon 8. Direct sequencing showed that these abnormal profiles were due to monoallelic transitions and transversions. We also found three polymorphic sequence changes that have been reported previously and annotated to an online database (http://www.uni-wuerzburg.de/humangenetics/vmd2.html).

Bestrophins↗

[New strategies in the management of retinoblastoma].

It was rare that a child survived retinoblastoma at the beginning of the twentieth century. Today the survival rate is in the order of 95% in reference centers, with new strategies improving prognosis step by step. Systematic enucleation used to be the starting point of any true and structured management, until the advent of radiotherapy made it possible not only to save lives but also to retain some useful vision. Early diagnosis has enabled focal therapies such as photocoagulation, cryocoagulation, and radioactive applicators to open up a new era of targeted tumor treatment. However, the onset of nonocular tumors secondary to radiotherapy, the resistance of certain tumors to irradiation, and unsightly cosmetic consequences all justify research into alternative therapeutic strategies. New types of chemotherapy have shown spectacular results and are currently under study: chemoreduction to make large tumors more manageable and enable less aggressive treatment of tumors located in delicate sites, thermochemotherapy using the effect of heat on plasma membrane permeability to antimitotics, and chemotherapy associated with cyclosporine to reduce the multidrug resistance of certain tumors. The aim is to avoid primary enucleation and external beam radiation as far as possible. The future may lie in local chemotherapy, hyperthermia, and dynamic phototherapy, accelerated proton beam radiotherapy also has promising prospects.

Antineoplastic Agents↗

Leber's hereditary optic neuropathy mitochondrial DNA mutations in normal-tension glaucoma.

BACKGROUND: in Leber's hereditary optic neuropathy, increased optic nerve cupping has been reported by several authors. Recently, a mitochondrial DNA (mtDNA) mutation at nucleotide 11778 typically associated with Leber's hereditary optic neuropathy (LHON) was identified in a patient treated for glaucoma but lacking typical signs of LHON. The question arises: should all normal-tension glaucoma patients be further evaluated for LHON? METHODS: we screened 54 unselected patients with normal-tension glaucoma (age range 20-96 years, 16 men and 38 women) for the primary mtDNA LHON mutations at nucleotides 3460, 11778 and 14484. RESULTS: none of the patients harboured the mtDNA mutations at nucleotides 3460, 11778 or 14484 (95% confidence intervals for each mutation ranged from 0% to 5.3%). CONCLUSIONS: primary LHON mtDNA mutations are rare or absent in unselected normal-tension glaucoma patients. Therefore, unselected normal-tension glaucoma patients should not be screened for these mutations. It is probable that only normal-tension glaucoma patients with atypical features (rapid progression, early deep central scotoma, pallor of neuroretinal rim, elevated disc, peripapillary teleangiectasia) or a positive family history of visual loss compatible with a matrilinear transmission should be further evaluated.

Adult↗

[Diagnosis and treatment of intraocular tumors in the child].

PURPOSE: To remind of the absolute necessity for early diagnosis in the presence of ocular signs in children giving rise to possible intraocular tumours. METHOD: Based on our own experience of intraocular tumours in children, together with findings from the literature, diagnostic criteria and methods of treatment are presented. RESULTS: Retinoblastoma is the predominant cause of intraocular tumours in children, representing over 80% of cases under the age of 15 years. Other diseases may give rise to the same initial signs, usually leukocoria, sometimes strabismus, more rarely other atypical signs. Elements taken into account for diagnosis include age, sex, laterality, heredity, size of the globe, clinical aspect of the tumours, presence of calcifications and vitreous seeding. Full fundus examination under general anaesthetic is usually necessary. Biological examination, ultrasonography, computerized tomography and MRI enable an accurate diagnosis to be made in the majority of doubtful cases. The management of retinoblastoma is adapted for each individual case from the wide range of treatments available. Enucleation, radioactive applicators (...), brachytherapy (...), cryo- and photocoagulation represent classical measures. Primary chemotherapy, combined with other treatments such as thermotherapy, has become the treatment of choice in those cases where external beam radiotherapy has been used up to now, or in some instances before enucleation. Enucleation is usually carried out for medullo-epitheliomas, but brachytherapy may offer an alternative. CONCLUSION: Any unexplained ocular sign in children should be considered as a possible retinoblastoma, making an accurate and certain diagnosis imperative. Early treatment may save not only the life but also the vision of patients carrying this highly malignant lesion.

Child↗

Mutations of the gene encoding the transmembrane transporter protein ABC-C6 cause pseudoxanthoma elasticum.

We recently published the precise chromosomal localization on chromosome 16p13.1 of the genetic defect underlying pseudoxanthoma elasticum (PXE), an inherited disorder characterized by progressive calcification of elastic fibers in skin, eye, and the cardiovascular system. Here we report the identification of mutations in the gene encoding the transmembrane transporter protein, ABC-C6 (also known as MRP-6), one of the four genes located in the region of linkage, as cause of the disease. Sequence analysis in four independent consanguineous families from Switzerland, Mexico, and South Africa and in one non-consanguineous family from the United States demonstrated several different mis-sense mutations to cosegregate with the disease phenotype. These findings are consistent with the conclusion that PXE is a recessive disorder that displays allelic heterogeneity, which may explain the considerable phenotypic variance characteristic of the disorder.

ATP-Binding Cassette Transporters↗

Meiotic segregation analysis of RB1 alleles in retinoblastoma pedigrees by use of single-sperm typing.

In hereditary retinoblastoma, different epidemiological studies have indicated a preferential paternal transmission of mutant retinoblastoma alleles to offspring, suggesting the occurrence of a meiotic drive. To investigate this mechanism, we analyzed sperm samples from six individuals from five unrelated families affected with hereditary retinoblastoma. Single-sperm typing techniques were performed for each sample by study of two informative short tandem repeats located either in or close to the retinoblastoma gene (RB1). The segregation probability of mutant RB1 alleles in sperm samples was assessed by use of the SPERMSEG program, which includes experimental parameters, recombination fractions between the markers, and segregation parameters. A total of 2,952 single sperm from the six donors were analyzed. We detected a significant segregation distortion in the data as a whole (P=.0099) and a significant heterogeneity in the segregation rate across donors (.0092). Further analysis shows that this result can be explained by segregation distortion in favor of the normal allele in one donor only and that it does not provide evidence of a significant segregation distortion in the other donors. The segregation distortion favoring the mutant RB1 allele does not seem to occur during spermatogenesis, and, thus, meiotic drive may result either from various mechanisms, including a fertilization advantage or a better mobility in sperm bearing a mutant RB1 gene, or from the existence of a defectively imprinted gene located on the human X chromosome.

Adult↗

First-line chemotherapy with local treatment can prevent external-beam irradiation and enucleation in low-stage intraocular retinoblastoma.

PURPOSE: To evaluate the efficacy of first-line chemotherapy (CT) in preventing external-beam radiotherapy (EBR) and/or enucleation in patients with retinoblastoma (Rbl). PATIENTS AND METHODS: Twenty-four patients with newly diagnosed unilateral or bilateral Rbl received CT associated with local treatment (LT). Two to five courses of etoposide and carboplatin were administered at 3- to 4-week intervals, depending on tumor response, and were completed each time by LT. RESULTS: Tumor response was observed in all eyes. Twenty-one of 24 patients showed a complete response (CR) that persisted at a median follow-up (FU) of 31 months (range, 4 to 41 months). Among the three patients who relapsed, two were lost to FU and one died of progressive disease. CR was achieved by CT and LT alone in 15 (71.4%) of 21 patients with less advanced disease (groups I to III). Six other patients with advanced disease (groups IV and V) experienced treatment failure and needed salvage treatment by EBR and/or enucleation. The difference between the two patient groups with regard to disease stage was statistically significant (P <.0001). EBR could be avoided in 13 (68.4%) of 19 patients, who presented with groups I to III (15 eyes) and group V (one eye) disease, whereas enucleation could be avoided in only two (40%) of five. CONCLUSION: CT combined with intensive LT is effective in patients with groups I to III Rbl, permitting the avoidance of EBR in the majority of these young children and, thus, reducing the risk of long-term sequelae. This is in contrast with the disappointing results for patients with groups IV and V Rbl, in whom EBR and/or enucleation was needed.

Adolescent↗

[Leukokoria in a child: emergency and challenge].

PURPOSE: To heighten the awareness of the medical world to the importance of correct and rapid diagnosis in the presence of leukocoria in the child. METHODS: Starting with the presenting symptom, the authors present the guide lines to follow in a practical manner in order to reach a diagnosis in the principal retinal diseases causing leukocoria. RESULTS: A white pupil is due to retinoblastoma in almost half of all cases. Other possible causes, in order of frequency, are: persistent hyperplastic primary vitreous, Coats' disease, ocular toxocariasis, retinopathy of prematurity, retinal hamartomas. Diagnosis can usually readily be made by ophthalmoscopy, but may be problematic when the clinical presentation is atypical or in the presence of late complications. Age, sex, laterality, heredity, and in particular the presence or absence of calcifications and the size of the globe, are the main criteria for diagnosis. Ultrasonography plays a major role in this essential quest for correct diagnosis, quest which may ultimately lead to enucleation. CONCLUSION: Leukocoria in the child is a danger signal demanding certain diagnosis within the shortest possible time.

Child↗

Familial subepithelial corneal amyloidosis (gelatinous drop-like corneal dystrophy): exclusion of linkage to lactoferrin gene.

PURPOSE: Because corneal tissue with familial subepithelial corneal amyloidosis (FSCA; gelatinous drop-like dystrophy of the cornea) contains lactoferrin the possibility that the FSCA gene was the human lactoferrin (hLF) gene was investigated. Due to contradictory published information we also mapped the hLF gene. METHODS: We mapped the hLF gene using a genomic clone of the entire hLF gene as a probe by fluorescence in situ hybridization (FISH). Utilizing PCR primers that are specific to the hLF gene, we also mapped the hLF via radiation somatic cell hybrid analysis. Linkage of the FSCA gene to the hLF gene was evaluated by genetic linkage analysis using polymorphic markers within and in the vicinity of the hLF gene. RESULTS: The hLF gene mapped to the short arm of chromosome 3 at 3p21. Linkage analysis using polymorphic markers for hLF and haplotype analysis of the 3p21 loci indicates that the FSCA gene is not linked to the 3p21 locus. CONCLUSIONS: The gene for FSCA is not the hLF gene in these families.

Amyloidosis↗

Identification of a new heterozygous point mutation in the COL1A2 gene leading to skipping of exon 9 in a patient with joint laxity, hyperextensibility of skin and blue sclerae. Mutations in brief no. 166. Online.

A heterozygous deletion of exon 9 in the COL1A2-mRNA of a patient with symptoms of both the Ehlers-Danlos-Syndrome and the Osteogensis Imperfecta is described. In the genomic DNA of the patient, exon 9 is homozygously present. We identified a novel heterozygous point mutation in the splice donor site of intron 9, leading to a G-->A substitution in position +5. This mutation leads to heterozygous skipping of exon 9 in the COL1A2-mRNA of this patient. The deletion results in a shortened (by 18 amino acids) but in frame 12(1) chain, which probably leads to the formation of abberantly processed triple helices.

Alternative Splicing↗