| Conditions: |
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Albinism - Oculocutaneous Albinism - Foveal Hypoplasia - Hypopigmentation - Nystagmus |
| Purpose: |
|
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 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.
|
| Criteria: |
|
- INCLUSION CRITERIA:
Patients will be considered to have a convincing diagnosis of OCA if they have cutaneous
evidence of hypopigmentation plus:
A. Iris transillumination documented in writing or by photograph by an ophthalmologist;
AND/OR
B. Evidence of characteristic axon-misrouting by visual evoked potential; AND/OR
C. Other visual deficits consistent with albinism, including nystagmus and/or foveal
hypoplasia.
EXCLUSION CRITERIA:
A patient will be excluded if she/he:
A. Has been diagnosed with a known non-oculocutaneous disorder of hypopigmentation such as
Hemansky-Pudlak Syndrome, Chediak-Higashi Syndrome, or Griscelli Syndrome.
B. Has been diagnosed with a known disorder of focal hypopigmentation such as Waardenburg
syndrome.
C. Is too sick to travel to the NIH.
D. If an infant under one year of age. This exclusion occurs because there is no urgency
for a very early evaluation. Also, the Clinical Center staff and resources are more suited
for the care of older children.
|
| NCT ID: |
|
NCT00808106 |
| Primary Contact: |
|
Principal Investigator
David R Adams, M.D.
National Human Genome Research Institute (NHGRI)
David R Adams, M.D.
Phone: (443) 254-3376
Email: dadams1@mail.nih.gov
|
| Backup Contact: |
|
N/A |
| Location Contact: |
|
Bethesda, Maryland 20892
United States
For more information at the NIH Clinical Center contact Patient Recruitment and Public Liaison Office (PRPL)
Phone: 800-411-1222
Email: prpl@mail.cc.nih.gov
Site Status: Recruiting |