Biomedical subjects

Elias Traboulsi

Publications and source records attributed to Elias Traboulsi.

7 recordsLinked to original sources

PubMed2004

Color vision testing.

The science of color vision testing has evolved since its inception in the late 1700s. Since then, the rudimentary technique of comparing color names has been replaced by more sophisticated methods. Commonly used tests in clinical practice today include isochromatic plates, arrangement tests, anomaloscopes, and lantern tests. Each category has unique attributes that make it suitable for a particular clinical situation. The clinician should be aware of the requirements for administering and grading each test type. Factors such as the quality of the illuminant and the size of the field of view are important elements in setting up a proper color vision laboratory. Currently, no treatment exists for congenital color vision defects. However, studies show that diagnosis of these defects early in life may help children adjust better to tasks at school and may help adults understand their limitations at work. Acquired color vision defects are often used as markers of ocular pathology in the clinical setting. Different color vision tests are appropriate for diagnosing the different categories of defects. Sometimes, a battery of tests may be appropriate. This paper is a review of the current knowledge in the field of color vision testing.

Color Perception↗

PubMed2004

A missense mutation in GUCY2D acts as a genetic modifier in RPE65-related Leber Congenital Amaurosis.

Leber congenital amaurosis (LCA) is a clinically and genetically heterogeneous severe retinal dystrophy presenting in infancy. To explain the phenotypical variability observed in two affected siblings of a consanguineous pedigree diagnosed with LCA and establish a genotype-phenotype correlation, we screened GUCY2D, RPE65, CRX, AIPL1, and RPGRIP1 for mutations. The more severely affected sibling carried a heterozygous missense mutation in the GUCY2D gene (Ile539Val), which did not segregate with the disease phenotype. Subsequently, a homozygous nonsense mutation (Glu102STOP) in the RPE65 gene was identified in both affected siblings, thus identifying the causative gene. This data provides evidence for the presence of genetic modulation in LCA. It appears that the heterozygous GUCY2D mutation further disrupts the already compromised photoreceptor function resulting in more severe retinal dysfunction in the older sibling. We suggest that the unusual phenotypic variability in these two siblings with LCA is caused by the modifying effect of a heterozygous GUCY2D mutation observed against the disease background of a homozygous RPE65 mutation.

Adult↗

PubMed2004

Ocular findings in ichthyosis follicularis-alopecia-photophobia (IFAP) syndrome.

PURPOSE: To report the ocular findings in two siblings with IFAP and their mother and to review the natural course of the keratopathy of this disease. METHODS: Clinical ophthalmological examination of all patients and fundus photography of the carrier mother were performed. RESULTS: Both affected male children had severe photophobia, total superficial and deep corneal vascularization, and reduction of vision to counting fingers.The mother had tortuous retinal vessels. CONCLUSIONS: Males with IFAP have an inexorable progression of corneal vascularization and loss of vision. Retinal vascular tortuosity may be another clinical sign of carrier status in females.

Abnormalities, Multiple↗

PubMed2004

Mutations of VMD2 splicing regulators cause nanophthalmos and autosomal dominant vitreoretinochoroidopathy (ADVIRC).

PURPOSE: To investigate the genetic basis of autosomal dominant vitreoretinochoroidopathy (ADVIRC), a rare, inherited retinal dystrophy that may be associated with defects of ocular development, including nanophthalmos. METHODS: A combination of linkage analysis and DNA sequencing in five families was used to identify disease-causing mutations in VMD2. The effect of these mutations on splicing was assessed using a minigene system. RESULTS: Three pathogenic sequence alterations in VMD2 were identified in five families with nanophthalmos associated with ADVIRC. All sequences showed simultaneous missense substitutions and exon skipping. CONCLUSIONS: VMD2 encodes bestrophin, a transmembrane protein located at the basolateral membrane of the RPE, that is also mutated in Best macular dystrophy. We support that each heterozygous affected individual produces three bestrophin isoforms consisting of the wild type and two abnormal forms: one containing a missense substitution and the other an in-frame deletion. The data showed that VMD2 mutations caused defects of ocular patterning, supporting the hypothesized role for the RPE, and specifically VMD2, in the normal growth and development of the eye.

Bestrophins↗

PubMed2003

A strabismus susceptibility locus on chromosome 7p.

Strabismus has been known to have a significant genetic component, but the mode of inheritance and the identity of the relevant genes have been enigmatic. This paper reports linkage analysis of nonsyndromic strabismus. The principal results of this study are: (i) the demonstrated feasibility of identifying and recruiting large families in which multiple members have (or had) strabismus; (ii) the linkage in one large family of a presumptive strabismus susceptibility locus to 7p22.1 with a multipoint logarithm of odds score of 4.51 under a model of recessive inheritance; and (iii) the failure to observe significant linkage to 7p in six other multiplex families, consistent with genetic heterogeneity among families. These findings suggest that it will be possible to localize and ultimately identify strabismus susceptibility genes by linkage analysis and mutation screening of candidate genes.

Chromosome Mapping↗

PubMed2003

Latent nystagmus and acquired pendular nystagmus masquerading as spasmus nutans.

SUMMARY: We used ocular motility recordings to identify the characteristics of a rare combination of conjugate, horizontal jerk, and pendular nystagmus in a 9-year-old boy. The clinical diagnoses were amblyopia, left esotropia, congenital nystagmus, and an apparently uniocular pendular nystagmus that mimicked spasmus nutans. Ocular motility recordings revealed an unusual latent/manifest latent nystagmus, pendular nystagmus with characteristics of an acquired nystagmus, and uniocular saccades. The ocular motor data identified clinically unrecognized types of nystagmus and suggested that the pendular nystagmus was acquired in infancy rather than as a result of failure to develop good vision or binocularity. The presence of uniocular saccades adds to the mounting evidence that individual control for each eye exists in humans.

Child↗

PubMed2002

Aberrant accumulation of EFEMP1 underlies drusen formation in Malattia Leventinese and age-related macular degeneration.

Malattia Leventinese (ML), an inherited macular degenerative disease, is closely reminiscent of age-related macular degeneration (AMD), the most common cause of incurable blindness. Both ML and AMD are characterized by extracellular deposits known as drusen between the retinal pigment epithelium (RPE) and Bruch's membrane. The mechanism underlying drusen formation is unknown. An Arg to Trp mutation in a gene of unknown function, EFEMP1, is responsible for ML, indicating EFEMP1 may be important in drusen formation. Here, we show that wild-type EFEMP1 is a secreted protein whereas mutant EFEMP1 is misfolded, secreted inefficiently, and retained within cells. In normal eyes, EFEMP1 is not present at the site of drusen formation. However, in ML eyes, EFEMP1 accumulates within the RPE cells and between the RPE and drusen, but does not appear to be a major component of drusen. Furthermore, in AMD eyes, EFEMP1 is found to accumulate beneath the RPE immediately overlaying drusen, but not in the region where there is no apparent retinal pathology observed. These data present evidence that misfolding and aberrant accumulation of EFEMP1 may cause drusen formation and cellular degeneration and play an important role in the etiology of both ML and AMD.

Age Factors↗