Preserved para-arteriolar retinal pigment epithelium retinitis pigmentosa

Selected pigmented fundus lesions of children

BACKGROUND

Ocular cells that accumulate melanin pigment are derived from 1 of 2 sources, the optic vesicle or the neural crest. Migration and distribution of pigment containing cells may go awry during fetal development or these cells may be altered before or after birth either by local or systemic stimuli. Specific recognition patterns of pigment distribution often exist and may relate directly to a single disease process.

METHODS

Records of pediatric patients with disorders of pigment distribution in the ocular fundi who had been examined by the author were reviewed.

RESULTS

Five disorders with recognizable patterns of retinal pigment epithelium (optic vesicle derivation) disturbance (congenital hypertrophy of the retinal pigment epithelium, Gardner syndrome, chronic granulomatous disease, preserved para-arteriole retinal pigment epithelium in (autosomal-recessive) retinitis pigmentosa, and combined hamartoma of the retina and retinal pigment epithelium), and 5 disorders of cells originating from the neural crest (choroidal nevi, choroidal melanoma, melanocytoma, ocular melanosis, and oculodermal melanosis), were selected for illustration and discussion.

CONCLUSIONS

These arbitrarily selected groups of disorders affect or involve patterns of pigment deposition in the ocular fundus. These patterns are recognizable and distinguishable one from another but have different implications for treatment and follow-up. Progress in recognizing distinguishing characteristics, diagnostic implications, understanding, and treatment of these disorders during the past 40 years is compared and contrasted between the 2 groups.

CRB1 mutations may result in retinitis pigmentosa without para-arteriolar RPE preservation

PURPOSE

To report a new phenotype in retinitis pigmentosa (RP) patients with CRB1 mutations at the RP12 locus.

PATIENTS

Thirty-seven patients from two Pakistani families with severe retinitis pigmentosa.

METHODS

Samples were screened with single-strand conformation polymorphism analysis followed by DNA sequencing of the coding sequence of the CRB1 gene.

RESULTS

Two novel CRB1 mutations were discovered. No patients had evidence of preservation of the para-arteriolar retinal pigment epithelium (PPRPE) that has been previously reported in all cases of RP associated with CRB1 mutations.

CONCLUSIONS

Patients with severe autosomal recessive (or simplex) RP who lack the finding of PPRPE should not be excluded from molecular analysis of CRB1 purely because they lack the clinical feature of PPRPE. This report illustrates that RP at the RP12 locus is not clinically uniform. The absence of PPRPE cannot be used to exclude CRB1 as a potential molecular explanation for RP.

Autosomal recessive retinitis pigmentosa with preserved para-arteriolar retinal pigment epithelium

Retinitis pigmentosa with preserved para-arteriolar retinal pigment epithelium is a rare form of retinitis pigmentosa that starts early in life with preservation of retinal pigment epithelium adjacent to and under the retinal arterioles and that has hitherto been described as an isolated form. We examined 22 patients from one large family, together with two isolated patients, and confirmed the presumed autosomal recessive mode of inheritance in this type of retinitis pigmentosa. New findings associated with retinitis pigmentosa with preserved para-arteriolar retinal pigment epithelium were asteroid hyalosis in four (17%) of 24 patients, tortuosity of retinal arterioles in 11 (46%) of 24 patients, peripheral regions of opacified vessels in eight (33%) of 24 patients, and preservation not only of the para-arteriolar pigment epithelium, but also of the peripheral retinal pigment epithelium in 13 (54%) of 24 patients. Previously reported signs present in these patients were nystagmus in six (25%) of 24 patients, hypermetropia in 23 (96%) of 24 patients, optic nerve head drusen in nine (38%) of 24 patients, vascular sheathing in 11 (46%) of 24 patients, maculopathy in all 24 patients (100%), yellow round deposits in the posterior pole in nine (38%) of 24 patients, exudates resembling those in Coats' disease in two (8%) of 24 patients, visual field defects in all 24 patients (100%), and nondeductible electroretinograms in 21 (91%) of 23 patients. Linkage analysis carried out in the large family resulted in the assignment of a gene for retinitis pigmentosa with preserved para-arteriolar retinal pigment epithelium to chromosome 1q31-q32.1.

Genetic isolate and preserved para-arteriole retinal pigment epithelium

Preserved para-arteriole retinal pigment epithelium (PPRPE) is an uncommon form of retinitis pigmentosa, with a very peculiar funduscopic appearance. To our knowledge no patient under age ten, affected by PPRPE, has been reported in the literature. The authors present here a seven-year-old boy, whose fundus examination is consistent with the diagnosis of PPRPE. The case report confirms that PPRPE starts early in childhood, and additionally supports the hypothesis of an autosomal recessive inheritance of this condition, since the proband's family lives in a 'genetic isolate'.