<p><b>OBJECTIVE</b>To identify the
mutations of the
tyrosinase gene (TYR) and P
gene in
patients with
oculocutaneous albinism (OCA).</p><p><b>
METHODS</b>
Polymerase chain reaction (
PCR) and denaturing
high performance liquid chromatography (DHPLC) were applied to detect the
mutations in all
exons of TYR
gene and P
gene. Then
DNA sequencing and
restriction endonuclease analysis were used to confirm the
mutations detected by DHPLC. Novel
mutations were screened in 100 unrelated
persons with normal
phenotypes to exclude the possibility of polymorphism.</p><p><b>RESULTS</b>Two
mutations were detected in the P
gene of the three
patients and none in TYR
gene. Heterozygous
mutation of T450M in
exon 13 of the P
gene was detected in
patient 1.
Patient 2 had a heterozygous
mutation of T450M in
exon 13 and a heterozygous
mutation of G775R in
exon 23 of the P
gene.
Patient 3 had a heterozygous
mutation of G775R as well.
Restriction endonuclease analysis of the P
gene exon 13 showed that the Oli I site had partly disappeared resulting from the heterozygous
mutation T450M in
patient 1 and
patient 2, but not in 100 unrelated individuals. The heterozygous
mutation T450M is a novel
mutation.</p><p><b>CONCLUSION</b>
Gene diagnosis of OCA can be carried out effectively by combining
PCR, DHPLC,
DNA sequencing and
restriction endonuclease analysis.</p>