Human oculocutaneous albinism caused by single base insertion in the tyrosinase gene.
Tyrosinase-negative oculocutaneous albinism (OCA) is an inborn error of metabolism, characterized by a complete lack of melanin pigments in the eyes and skin. We have isolated and characterized the tyrosinase gene of one affected child (S.S.) with tyrosinase-negative OCA. Sequence analysis reveals a single-base insertion in the exon 2 that shifts the reading frame and introduces a premature termination signal (TGA codon) after the amino acid residue 298. Functional analysis of the mutated gene indicates that such a truncated tyrosinase lacking one potential copper-binding region is catalytically inactive. We therefore conclude that the albino phenotype of the patient S.S. is a consequence of the inactive tyrosinase caused by the nonsense mutation in the tyrosinase gene.
Tomita
Y
Y
Department of Applied Physiology, Tohoku University School of Medicine, Miyagi, Japan.
Takeda
A
A
Okinaga
S
S
Tagami
H
H
Shibahara
S
S
D000417:Albinism / Q000201:enzymology / Q000235:genetics*; D000595:Amino Acid Sequence; D001483:Base Sequence; D004156:Catechol Oxidase / Q000235:genetics*; D003001:Cloning, Molecular; D004247:DNA / Q000097:blood / Q000235:genetics; D005260:Female; D005784:Gene Amplification; D005796:Genes; D015698:Genomic Library; D006801:Humans; D008214:Lymphocytes / Q000201:enzymology; D008297:Male; D008969:Molecular Sequence Data; D014442:Monophenol Monooxygenase / Q000097:blood / Q000235:genetics*; D009154:Mutation; D015345:Oligonucleotide Probes; D010375:Pedigree; D015183:Restriction Mapping
D015345:Oligonucleotide Probes; D004247:DNA; D004156:Catechol Oxidase; D014442:Monophenol Monooxygenase