Mutation in and lack of expression of tyrosinase-related protein-1 (TRP-1) in melanocytes from an individual with brown oculocutaneous albinism: A new subtype of albinism classified as {open_quotes}OCA3{close_quotes}

Journal Article · Sat Jun 01 04:00:00 EDT 1996 · American Journal of Human Genetics

OSTI ID:446930

Boissy, R E; Zhao, H; Austin, L M; Boissy, Y L; Zhao, Y ^[1]

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1. Univ. of Cincinnati College of Medicine, OH (United States); and others

Most types of human oculocutaneous albinism (OCA) result from mutations in the gene for tyrosinase (OCA1) or the P protein (OCA2), although other types of OCA have been described but have not been mapped to specific loci. Melanocytes were cultured from an African-American with OCA, who exhibited the phenotype of Brown OCA, and his normal fraternal twin. Melanocytes cultured from the patient with OCA and the normal twin appeared brown versus black, respectively. Melanocytes from both the patient with OCA and the normal twin demonstrated equal amounts of NP-40-soluble melanin; however, melanocytes from the patient with OCA contained only 7% of the amount of insoluble melanin found from the normal twin. Tyrosinase-related protein-1 (TRP-1) was not detected in the OCA melanocytes by use of various anti-TRP-1 probes. Furthermore, transcripts for TRP-1 were absent in cultured OCA melanocytes. The affected twin was homozygous for a single-bp deletion in exon 6, removing an A in codon 368 and leading to a premature stop at codon 384. Tyrosine hydroxylase activity of the OCA melanocytes was comparable to controls when assayed in cell lysates but was only 30% of controls when assayed in intact cells. We conclude that this mutation of the human TRP-1 gene affects its interaction with tyrosinase, resulting in dysregulation of tyrosinase activity, promotes the synthesis of brown versus black melanin, and is responsible for a third genetic type of OCA in humans, which we classify as {open_quotes}OCA3.{close_quotes} 69 refs., 7 figs., 3 tabs.

• OSTI ID: 446930
• Journal Information: American Journal of Human Genetics, Journal Name: American Journal of Human Genetics Journal Issue: 6 Vol. 58; ISSN AJHGAG; ISSN 0002-9297
• Country of Publication: United States
• Language: English

Related Subjects

55 BIOLOGY AND MEDICINE
BASIC STUDIES
ANIMAL CELLS
ANTIBODIES
BIOSYNTHESIS
DNA SEQUENCING
ENZYME ACTIVITY
EXONS
GENE MUTATIONS
GENES
GENETIC MAPPING
MELANIN
PATIENTS
PHENOTYPE
PROBES
PROTEINS
SKIN DISEASES
TRANSCRIPTION
TYROSINASE