Form Of Retinitis Pigmentosa Research Articles

Visual Pigments, Blue Cone Monochromasy, and Retinitis Pigmentosa

In a recent publication, Dryja and colleagues 1 reported a point mutation of the rhodopsin gene in one form of retinitis pigmentosa (RP). The mutation, a cytosine-to-adenine base transversion, results in the substitution of histidine (His) for proline (Pro) at position 23 of the rhodopsin protein. In heterozygotes for this mutation with one normal and one abnormal copy of the rhodopsin gene, this alteration appears to cause rod cell dysfunction, a characteristic finding in RP. To see rhodopsin in the forefront of research gives me a feeling of deja vu. It reminds me of what George Wald, 2 who shared the Nobel Prize for his work on rhodopsin, said in 1972: I feel a little like that character in Moliere's play who learned with delight that all his life he had been speaking prose . In the visual pigments we are working with membrane proteins , and membranes and their structure are,

Analysis of the DNA of patients with retinitis pigmentosa with a cellular retinaldehyde binding protein cDNA

We used a cDNA fragment corresponding to the human cellular retinaldehyde binding protein (CRALBP) gene to search for mutations at this locus in patients with autosomal dominant, autosomal recessive, or isolate retinitis pigmentosa, and Usher's syndrome, type I. No gene deletions or rearrangements could be detected in any patient by Southern blotting. We identified a Pvu II restriction fragment length polymorphism (RFLP) defining two alleles at the CRALBP locus in the normal population. We used this RFLP to analyze the genomic DNA of large sets of unrelated patients with autosomal dominant, autosomal recessive, or isolate retinitis pigmentosa. Within each of these groups, RFLP alleles at the CRALBP locus showed no linkage disequilibrium (departure from Hardy-Weinberg equilibrium). In addition, two autosomal dominant, two autosomal recessive, and three Usher's syndrome, type I pedigrees each showed no cosegregation of the CRALBP locus and the disease locus. We could find no evidence that mutations of the CRALBP gene are associated with the common forms of retinitis pigmentosa or Usher's syndrome, type I.

A point mutation of the rhodopsin gene in one form of retinitis pigmentosa

The gene for autosomal dominant retinitis pigmentosa in a large pedigree of Irish origin has recently been found to be linked to an anonymous polymorphic sequence, D3S47 (C17), from the long arm of chromosome 3. As the gene coding for rhodopsin is also assigned to the long arm of chromosome 3 and is expressed in rod photoreceptors that are affected early in this blinding disease, we searched for a mutation of the rhodopsin gene in patients with autosomal dominant retinitis pigmentosa. We found a C----A transversion in codon 23 (corresponding to a proline----histidine substitution) in 17 of 148 unrelated patients and not in any of 102 unaffected individuals. This result, coupled with the fact that the proline normally present at position 23 is highly conserved among the opsins and related G-protein receptors, indicates that this mutation could be the cause of one form of autosomal dominant retinitis pigmentosa.

Retinitis pigmentosa. A mimic of neurologic disease

Six patients with various forms of retinitis pigmentosa who were misdiagnosed as having neurologic disease are presented. In five of the patients, visual field defects were misinter-preted as being secondary to a neurologic rather than a retinal problem. In two patients, optic nerve drusen, which accompanied the retinal degeneration, were mistaken for papilledema. Since the diagnosis of retinitis pigmentosa is not always obvious on ophthalmoscopy, the clinician must be aware of the various manifestations of this disorder and be able to distinguish visual field defects on a retinal from a neurologic basis.

Dark-adapted foveal thresholds and visual acuity in retinitis pigmentosa.

To determine the relationship of foveal absolute thresholds to visual acuity in retinitis pigmentosa, we measured thresholds in 40 patients with various forms of retinitis pigmentosa (including Usher's syndrome) whose Snellen visual acuities were 20/30 or better. At all visual acuity levels, the patients' foveal thresholds were significantly higher than those of 20 similarly aged normal observers; threshold elevations tended to be greater for a 500-nm than for a 655-nm test flash. Foveal cone spatial summation functions were normal (test flash diameter range, 7' to 1.7 degrees), indicating that the patients' threshold elevations did not result from altered summation properties. A significant correlation between foveal cone thresholds and the midpoints of the patients' Rayleigh matches demonstrated that the threshold elevations resulted in part from a decreased cone optical density.

Retinitis Pigmentosa: A Review of the Tapeto‐Retinal Dystrophies

: The signs and symptoms, clinical course, underlying pathology, hereditary characteristics and management of retinitis pigmentosa are reviewed. Aberrant forms of retinitis pigmentosa are discussed and those syndromes in which retinitis pigmentosa feature are listed.

20 Syndromes Oculaires: Heredo-Familiaux & Congenitaux.

Prof E. Puscariu has classified 20 hereditofamilial and congenital ocular syndromes as follows: Syndromes with osteopathies: These include the phakomatoses, Lawrence-Moon-Bardet-Biedl syndrome, various forms of retinitis pigmentosa, blue sclerotics, Marfan-William, and Weil-Marchesani syndromes. Syndromes without osteopathies: Infectious syndromes: toxoplasmosis and rubeola. Ectodermatosis: Rothmund and Werner syndromes, xeroderma pigmentosa, and von Hippel-Lindau's angiomatosis. The craniofacial dysostoses. Apart from this rather unusual classification, this monograph contains no original material nor any critical analyses.