Topics

Clinical, Cellular, and Molecular Investigation Into Oculocutaneous Albinism

2014-08-27 03:25:41 | BioPortfolio

Summary

Oculocutaneous albinism (OCA) is a term used to describe inherited forms of hypopigmentation associated with 1) variable levels of cutaneous hypopigmentation, ocular hypopigmentation, and visual deficits, and 2) involvement of both of the major developmental types of pigmented cells, i.e., melanocytes and retinal pigment epithelium. OCA is considered isolated if it involves only tissues that are normally pigmented. The four known types of isolated oculocutaneous albinism (OCA-1 to OCA-4) are autosomal recessive disorders associated with specific genes. OCA-1 results from defects in the enzyme tyrosinase, which catalyzes the rate-limiting step in melanin synthesis. The precise functions of the genes associated with OCA2, OCA3 and OCA4 are not known. OCA-2 is caused by mutations in the OCA2 (or P) gene. OCA-3 and OCA-4 are rare, incompletely characterized conditions caused by the tyrosine-related protein 1 gene (TYRP1) and the SLC45A2 gene, respectively. Most OCA patients have two pathogenic mutations identified in an OCA-causing gene. In this protocol, we have 4 major goals. First, we want to clinically and comprehensively characterize OCA subtypes, especially OCA-1 and OCA-2, with respect to the degree of hypopigmentation, genetic mutations, and extent of ocular involvement. Second, we plan to study patients' cultured melanocytes for variability in pigment formation related to genotype, and test treatments to increase pigmentation. Third, we expect to ascertain rare patients with hypopigmentation not due to known albinism-causing genes. Finally, we will acquire sufficient experience in the care of patients with albinism to become experts in this disorder. This expertise will be especially valuable for potential future clinical trials. We will clinically evaluate patients of all ethnicities; obtain cells, plasma and urine for future studies; perform mutation analysis on known OCA causing genes; and search for other genes responsible for OCA. Routine admissions will last 4-5 days and occur every two years.

Description

Oculocutaneous albinism (OCA) is a term used to describe inherited forms of hypopigmentation associated with 1) variable levels of cutaneous hypopigmentation, ocular hypopigmentation, and visual deficits, and 2) involvement of both of the major developmental types of pigmented cells, i.e., melanocytes and retinal pigment epithelium. OCA is considered isolated if it involves only tissues that are normally pigmented. The four known types of isolated oculocutaneous albinism (OCA-1 to OCA-4) are autosomal recessive disorders associated with specific genes. OCA-1 results from defects in the enzyme tyrosinase, which catalyzes the rate-limiting step in melanin synthesis. The precise functions of the genes associated with OCA2, OCA3 and OCA4 are not known. OCA-2 is caused by mutations in the OCA2 (or P) gene. OCA-3 and OCA-4 are rare, incompletely characterized conditions caused by the tyrosine-related protein 1 gene (TYRP1) and the SLC45A2 gene, respectively. Most OCA patients have two pathogenic mutations identified in an OCA-causing gene. In this protocol, we have 4 major goals. First, we want to clinically and comprehensively characterize OCA subtypes, especially OCA-1 and OCA-2, with respect to the degree of hypopigmentation, genetic mutations, and extent of ocular involvement. Second, we plan to study patients' cultured melanocytes for variability in pigment formation related to genotype, and test treatments to increase pigmentation. Third, we expect to ascertain rare patients with hypopigmentation not due to known albinism-causing genes. Finally, we will acquire sufficient experience in the care of patients with albinism to become experts in this disorder. This expertise will be especially valuable for potential future clinical trials. We will clinically evaluate patients of all ethnicities; obtain cells, plasma and urine for future studies; perform mutation analysis on known OCA causing genes; and search for other genes responsible for OCA. Routine admissions will last 4-5 days and occur every two years.

Study Design

N/A

Conditions

Albinism

Location

National Institutes of Health Clinical Center, 9000 Rockville Pike
Bethesda
Maryland
United States
20892

Status

Recruiting

Source

National Institutes of Health Clinical Center (CC)

Results (where available)

View Results

Links

Published on BioPortfolio: 2014-08-27T03:25:41-0400

Clinical Trials [5 Associated Clinical Trials listed on BioPortfolio]

Visual Function and Ocular Pigmentation in Albinism

To study the relationship between visual function and ocular (iris, retina/choroidal) pigmentation in patients with albinism and other hypomelanotic disorders. To identify the carrier sta...

New Strategies of Genetic Study of Patients With Oculocutaneous Albinism

The oculocutaneous albinism is an autosomal recessive condition associated with mutations in 4 genes. In 20% of patients no mutation is identified. The optimization of genetic analysis met...

Clinical and Basic Investigations Into Hermansky-Pudlak Syndrome

Hermansky-Pudlak Syndrome (HPS) is an inherited disease which results in decreased pigmentation (oculocutaneous albinism), bleeding problems due to a platelet abnormality (platelet storage...

Genetic Determinant of Foveolar Hypoplasia in Parents of Albinos Children

Fovea plana could be the phenoyipic translation of a genetic anomaly in one of the genes identified in albinisme

Pilot Study of a Multi-Drug Regimen for Severe Pulmonary Fibrosis in Hermansky-Pudlak Syndrome

This study will examine whether five drugs (pravastatin, Losartan, Zileuton, N-acetylcysteine and erythromycin) used together can slow the course of pulmonary fibrosis (scarring of the lun...

PubMed Articles [15 Associated PubMed Articles listed on BioPortfolio]

Dermatological and Epidemiological Profiles of Patients with Albinism in São Paulo, Brazil, between 2010 and 2017: A Cross-Sectional Study.

Oculocutaneous albinism is an autosomal recessive disease caused by complete absence of or decrease in melanin biosynthesis in melanocytes. Due to the reduction or absence of melanin, albinos are high...

The Detection Of Misrouting In Albinism: Evaluation of Different VEP Procedures in a Heterogeneous Cohort.

To investigate the optimal procedures for multichannel visually evoked potentials (VEPs) to detect misrouting in albinism subjects.

Distribution of macular ganglion cell layer thickness in foveal hypoplasia: A new diagnostic criterion for ocular albinism.

To analyse the distribution of macular ganglion cell layer thickness (GCLT) in patients with foveal hypoplasia (FH) with or without albinism to obtain new insights into visual pathway anomalies in alb...

Understanding pseudo-albinism in sole (Solea senegalensis): a transcriptomics and metagenomics approach.

Pseudo-albinism is a pigmentation disorder observed in flatfish aquaculture with a complex, multi-factor aetiology. We tested the hypothesis that pigmentation abnormalities are an overt signal of more...

First record of albinism in the lanternshark family, Etmopteridae.

A single albino specimen of the lanternshark, Lucifer's shark (Etmopterus lucifer), is reported here. The specimen was found amongst museum collections, having been captured near Cape Palliser, off th...

Medical and Biotech [MESH] Definitions

Syndrome characterized by the triad of oculocutaneous albinism (ALBINISM, OCULOCUTANEOUS); PLATELET STORAGE POOL DEFICIENCY; and lysosomal accumulation of ceroid lipofuscin.

Albinism affecting the eye in which pigment of the hair and skin is normal or only slightly diluted. The classic type is X-linked (Nettleship-Falls), but an autosomal recessive form also exists. Ocular abnormalities may include reduced pigmentation of the iris, nystagmus, photophobia, strabismus, and decreased visual acuity.

General term for a number of inherited defects of amino acid metabolism in which there is a deficiency or absence of pigment in the eyes, skin, or hair.

Heterogeneous group of autosomal recessive disorders comprising at least four recognized types, all having in common varying degrees of hypopigmentation of the skin, hair, and eyes. The two most common are the tyrosinase-positive and tyrosinase-negative types.

Nystagmus present at birth or caused by lesions sustained in utero or at the time of birth. It is usually pendular, and is associated with ALBINISM and conditions characterized by early loss of central vision. Inheritance patterns may be X-linked, autosomal dominant, or recessive. (Adams et al., Principles of Neurology, 6th ed, p275)

More From BioPortfolio on "Clinical, Cellular, and Molecular Investigation Into Oculocutaneous Albinism"

Quick Search

Relevant Topics

Enzymes
Enzymes are proteins that catalyze (i.e., increase the rates of) chemical reactions. In enzymatic reactions, the molecules at the beginning of the process, called substrates, are converted into different molecules, called products. Almost all chemical re...

Bioinformatics
Bioinformatics is the application of computer software and hardware to the management of biological data to create useful information. Computers are used to gather, store, analyze and integrate biological and genetic information which can then be applied...


Searches Linking to this Trial