Clinical, Cellular, and Molecular Investigation Into Oculocutaneous Albinism
- Conditions
- Oculocutaneous Albinism
- Registration Number
- NCT00808106
- Lead Sponsor
- National Human Genome Research Institute (NHGRI)
- Brief 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 that affects only usually-pigmented tissues is termed isolated OCA. There are currently seven albinism types (OCA-1 to OCA-7). With the exception of OCA-5, eash is associated with a specific gene and is inherited in an autosomal recessive manner OCA-5 is a proposed type of albinism associated with the chromosomal location 4q24. OCA-1 results from defects in the enzyme tyrosinase, which catalyzes the rate-limiting step in melanin synthesis. The precise functions of the remaining genes are not yet fully understood, but several may be associated with the regulation of pH in the subcellular organelle where melanin in manufactured-the melanosome. The majority of persons with OCA have two pathogenic mutations identified in a known OCA-causing gene, but a substantial minority to not. Ocular albinism (OA) is an X-linked disorder caused by mutations in the GPR143 gene. It affects the eye in a manner similar to OCA, but has minimal or no skin manifestations.
In this protocol, we have four major goals:
1. To clinically and comprehensively characterize OCA types 1 - 7, and OA, with respect to the degree of hypopigmentation, genetic mutations, extent of ocular involvement, and longitudinal variation.
2. To use study participants cultured melanocytes to study pigment biology, variability in pigment formation related to genotype, and response to proposed treatments. Some of this work will be performed collaboratively.
3. To recruit study participants with hypopigmentation not due to known albinismcausing genes.
4. To evaluate methods of quantifying eye pigmentation, skin pigmentation and other clinical parameters that may be usable as outcome measures in future treatment studies.
To achieve those goals, we will perform clinical evaluations of persons with OCA and OA at the NIH Clinical Center; obtain cultured cells, plasma, serum and urine for future studies; and, perform mutation analysis on known OCA and/or OA genes and search for other genes responsible for albinism. Routine admissions will last 3 - 4 days and occur every 2 - 3 years.
- Detailed 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 that affects
only usually-pigmented tissues is termed isolated OCA. There are currently seven albinism
types (OCA-1 to OCA-7). With the exception of OCA-5, eash is associated with a specific
gene and is inherited in an autosomal recessive manner (see Table 1). OCA-5 is a proposed
type of albinism associated with the chromosomal location 4q24. OCA-1 results from defects
in the enzyme tyrosinase, which catalyzes the rate-limiting step in melanin synthesis. The
precise functions of the remaining genes are not yet fully understood, but several may be
associated with the regulation of pH in the subcellular organelle where melanin in
manufactured the melanosome. The majority of persons with OCA have two pathogenic
mutations identified in a known OCA-causing gene, but a substantial minority to not. Ocular
albinism (OA) is an X-linked disorder caused by mutations in the GPR143 gene. It affects the
eye in a manner similar to OCA, but has minimal or no skin manifestations.
In this protocol, we have four major goals:
1. To clinically and comprehensively characterize OCA types 1 7, and OA, with respect
to the degree of hypopigmentation, genetic mutations, extent of ocular involvement,
and longitudinal variation.
2. To use study participants cultured melanocytes to study pigment biology, variability
in pigment formation related to genotype, and response to proposed treatments. Some
of this work will be performed collaboratively
3. To recruit study participants with hypopigmentation not due to known albinismcausing
genes.
4. To evaluate methods of quantifying eye pigmentation, skin pigmentation and other
clinical parameters that may be usable as outcome measures in future treatment studies.
To achieve those goals, we will perform clinical evaluations of persons with OCA and OA at
the NIH Clinical Center; obtain cultured cells, plasma, serum and urine for future studies; and,
perform mutation analysis on known OCA and/or OA genes and search for other genes
responsible for albinism. Routine admissions will last 3 - 4 days and occur every 2 - 3 years.
Recruitment & Eligibility
- Status
- COMPLETED
- Sex
- All
- Target Recruitment
- 206
Not provided
Not provided
Study & Design
- Study Type
- OBSERVATIONAL
- Study Design
- Not specified
- Primary Outcome Measures
Name Time Method A Ongiong Collect data to refine existing knowledge about the range, course and severity of the visual, cutaneous, auditory and other potentialmanifestations of the various forms of OCA and of OA
B Ongoing Conduct laboratory studies on patients cultured melanocytes and other biologic specimens to further understand the cell biology ofpigment formation relative to genetic mutation
C Ongoing Pursue the discovery of novel molecular defects in patients who have albinism caused by mutations in pigmentation-related genes that have not yet been proven to be associated with human pigmentation disorders
D Ongoing Search for and evaluate methods of quantifying eye pigmentation, skin pigmentation and other clinical parameters that may be usable as outcome measures in future treatment studies
- Secondary Outcome Measures
Name Time Method
Trial Locations
- Locations (1)
National Institutes of Health Clinical Center, 9000 Rockville Pike
🇺🇸Bethesda, Maryland, United States