OBJECTIVE: To identify the causative variants in 13 Chinese pedigrees affected with oculocutaneous albinism (OCA) so as to provide genetic counseling and prenatal diagnosis to them. METHODS: Thirteen unrelated pedigrees with clinically diagnosed OCA were collected and classified based on the manifestation of skin and eyes. With informed consent obtained from the participants, peripheral blood samples were collected from the probands and their family members for the extraction of genomic DNA. Candidate variants were screened by targeted capture and next generation sequencing, and the results were validated by Sanger sequencing. Prenatal diagnosis was provided to the families upon their subsequent pregnancies. RESULTS: Causative variants were detected in all probands, including 10 with compound heterozygotes or homozygotes for TYR gene variants and 3 with compound heterozygotes for OCA2 gene variants. Among these, two variants [TYR: c.650G>C (p.Arg217Pro) and OCA2: c.516-2A>T] were unreported previously. The pathogenicity of the novel TYR: c.650G>C (p.Arg217Pro) variant was verified through bioinformatic analysis and prediction of three dimensional structure of the protein. Prenatal diagnosis was provided to 6 fetuses with a high risk for OCA. Four fetuses were found to be carriers, one did not carry the variants of the proband, and one was affected with OCA. CONCLUSION Identification of the pathogenic variants in the 13 probands, including 2 novel ones, has expanded the mutational spectrum of OCA and enabled genetic counseling and prenatal diagnosis for the families.
Albinism, Oculocutaneous/genetics* ; China ; Female ; Genetic Testing ; Humans ; Membrane Transport Proteins/genetics* ; Monophenol Monooxygenase/genetics* ; Mutation ; Pedigree ; Pregnancy ; Prenatal Diagnosis

Several chemical compounds can restore pigmentation in vitiligo through mechanisms that vary according to disease etiology. In the present study, we investigated the melanogenic activity of six structurally distinct compounds, namely, scopoletin, kaempferol, chrysin, vitamin D, piperine, and 6-benzylaminopurine. We determined their effectiveness, toxicity, and mechanism of action for stimulating pigmentation in B16F10 melanoma cells and in a zebrafish model. The melanogenic activity of 6-benzylaminopurine, the compound identified as the most potent, was further verified by measuring green fluorescent protein concentration in tyrp1 a: eGFP (tyrosinase-related protein 1) zebrafish and mitfa: eGFP (microphthalmia associated transcription factor) zebrafish and antioxidative activity. All the tested compounds were found to enhance melanogenesis responses both in vivo and in vitro at their respective optimal concentration by increasing melanin content and expression of TYR and MITF. 6-Benzyamino-purine showed the strongest re-pigmentation action at a concentration of 20 μmol·Lin vivo and 100 μmol·Lin vitro, and up-regulated the strong fluorescence expression of green fluorescent protein in tyrp1a: eGFP and mitfa: eGFP zebrafish in vitro. However, its relative anti-oxidative activity was found to be very low. Overall, our results indicated that 6-benzylaminopurine stimulated pigmentation through a direct mechanism, by increasing melanin content via positive regulation of tyrosinase activity in vitro, as well as up-regulating the expression of the green fluorescent protein in transgenic zebrafish in vivo.
Alkaloids ; chemistry ; pharmacology ; Animals ; Benzodioxoles ; chemistry ; pharmacology ; Benzyl Compounds ; chemistry ; pharmacology ; Cholecalciferol ; chemistry ; pharmacology ; Flavonoids ; chemistry ; pharmacology ; Humans ; Kaempferols ; chemistry ; pharmacology ; Melanins ; genetics ; metabolism ; Monophenol Monooxygenase ; genetics ; metabolism ; Pigmentation ; drug effects ; Piperidines ; chemistry ; pharmacology ; Polyunsaturated Alkamides ; chemistry ; pharmacology ; Purines ; chemistry ; pharmacology ; Scopoletin ; chemistry ; pharmacology ; Vitiligo ; drug therapy ; enzymology ; metabolism ; Zebrafish

OBJECTIVETo study the role of dysfunction of nuclear localization signals (NLS) of MITF protein in the pathogenesis of Waardenburg syndrome.

METHODSEukaryotic expression plasmid pCMV-MITF-Flag was used as a template to generate mutant plasmid pCMV-MITF△NLS-Flag by molecular cloning technique in order to design the mutagenic primers. The UACC903 cells were transfected transiently with MITF and MITF△NLS plasmids, and the luciferase activity assays were performed to determine their impact on the transcriptional activities of target gene tyrosinase (TYR). The oligonucleotide 5'-GAACGAAGAAGAAGATTT-3' was subcloned into pEGFP-N1 to generate recombinant eukaryotic expression plasmid pEGFP-N1-MITF-NLS. The NIH3T3 cells were transfected separately with MITF, MITF△NLS, pEGFP-N1 and pEGFP-N1-NLS plasmids, and their subcellular distribution was observed by immunoflorescence assays.

RESULTSExpression plasmids for the mutant MITF△NLS with loss of core NLS sequence and pEGFP-N1-NLS coupled with MITF△NLS were successfully generated. Compared with the wild-type MITF, MITF△NLS was not able to transactivate the transcriptional activities of promoter TYR and did not affect the normal function of MITF. MITF△NLS was only localized in the cytoplasm and pEGFP-N1 was found in both the cytoplasm and nucleus, whereas pEGFP-N1-NLS was mainly located in the nucleus.

CONCLUSIONThis study has confirmed the localization function of NLS sequence 213ERRRRF218 within the MITF protein. Mutant MITF with loss of NLS has failed to transactivate the transcriptional activities of target gene TYR, which can result in melanocyte defects and cause WS.

Amino Acid Sequence ; Animals ; Cell Line, Tumor ; Genetic Predisposition to Disease ; genetics ; Green Fluorescent Proteins ; genetics ; metabolism ; Humans ; Luciferases ; genetics ; metabolism ; Mice ; Microphthalmia-Associated Transcription Factor ; genetics ; metabolism ; Microscopy, Confocal ; Monophenol Monooxygenase ; genetics ; metabolism ; Mutation ; NIH 3T3 Cells ; Nuclear Localization Signals ; genetics ; Transcriptional Activation ; Transfection ; Waardenburg Syndrome ; diagnosis ; genetics ; metabolism

OBJECTIVETo perform genotyping analysis and subsequent prenatal genetic diagnosis for two families affected with oculocutaneous albinism (OCA).

METHODSDirect sequencing of TYR and P genes was performed in two albino probands. Family members were screened for corresponding mutant alleles. Prenatal genetic diagnoses were performed at early pregnancy by chorionic villus sampling (CVS) at mid-pregnancy through amniocentesis.

RESULTSNo mutations were detected in the TYR gene in either probands, whereas 4 heterozygous mutations of the P gene were found, namely c.406C>T, c.535A>G, c.808-2A>G and c.2180T>C, among which c.535A>G and c.808-2A>G were novel. In the first round prenatal genetic testing, both fetuses were found to have the same genotypes as the probands. Both families had decided to terminate the pregnancy after genetic counseling. In the second round testing, neither of the fetuses was found to be affected by genotyping. The pregnancies continued and two healthy fetuses were born.

CONCLUSIONOCA can be classified by genotyping, with which reliable prenatal diagnosis and feasible genetic counseling may be provided.

Adolescent ; Adult ; Albinism, Oculocutaneous ; diagnosis ; embryology ; enzymology ; genetics ; Asian Continental Ancestry Group ; genetics ; Base Sequence ; Child ; Child, Preschool ; Female ; Fetal Diseases ; diagnosis ; genetics ; Genotype ; Humans ; Infant ; Male ; Membrane Transport Proteins ; genetics ; Middle Aged ; Molecular Sequence Data ; Monophenol Monooxygenase ; genetics ; Pedigree ; Point Mutation ; Pregnancy ; Prenatal Diagnosis ; Young Adult

OBJECTIVETo evaluate the feasibility of genetic analysis of tyrosinase gene (TYR) in oculocutaneous albinism type I (OCA1). Mutation analysis and prenatal genetic diagnosis of TYR gene for seven pedigrees with OCA1 were performed.

METHODSPCR was used to amplify the exons, exon-intron boundaries and promoter of the TYR gene in the probands and/or their parents. The products were further analyzed by direct sequencing. Prenatal genetic diagnoses were performed by chorionic villus sampling after the genotypes of the probands or their parents were determined.

RESULTSCompound heterozygous mutations were detected in all pedigrees, which included 9 mutations, namely R76Q, c.232insGGG, R116X, R278X, R299H, c.929-930insC, IVS2-11delTT, Q399X and W400L. Among these, R76Q and Q399X were identified for the first time. Seven families have requested prenatal diagnoses. One fetus was detected with double mutations of TYR gene, and the parents have decided to have therapeutic abortion. Two fetuses did not carry the mutations identified in the probands, whilst other four fetuses were carriers of heterozygous mutations. Six families decided to carry on with the pregnancies. And the neonates did not show any symptoms of OCA after birth.

CONCLUSIONDirect sequencing of the TYR gene is helpful for genetic counseling, prenatal diagnosis and carriers screening of OCA1.

Albinism, Oculocutaneous ; diagnosis ; enzymology ; genetics ; Female ; Genetic Predisposition to Disease ; Humans ; Infant, Newborn ; Male ; Monophenol Monooxygenase ; genetics ; Mutation ; Pedigree ; Pregnancy ; Prenatal Diagnosis ; methods

BACKGROUNDThe mutation of the tyrosinase (TYR) gene results in oculocutaneous albinism type 1 (OCA1), an autosomal recessive genetic disorder. OCA1 is the most common type of OCA in the Chinese population. Hence, the TYR gene was tested in this study. We also delineated the genetic analysis of OCA1 in a Chinese family.

METHODSGenomic DNA was isolated from the blood leukocytes of a proband and his family. Mutational analysis at the TYR locus by DNA sequencing was used to screen five exons, including the intron/exon junctions. A pedigree chart was drawn and the fundus of the eyes of the proband was also examined.

RESULTSA novel missense mutation p.I151S on exon 1, and homozygous TYR mutant alleles were identified in the proband. None of the mutants was identified among the 100 normal control subjects. Genetic analysis of the proband's wife showed normal alleles in the TYR gene. Thus, the fetus was predicated a carrier of OCA1 with a normal appearance.

CONCLUSIONThis study provided new information about a novel mutation, p.I151S, in the TYR gene in a Chinese family with OCA1. Further investigation of the proband would be helpful to determine the effects of this mutation on TYR activity.

Adult ; Albinism, Oculocutaneous ; genetics ; Asian Continental Ancestry Group ; Female ; Genotype ; Humans ; Male ; Monophenol Monooxygenase ; genetics ; Mutation, Missense ; genetics ; Pedigree

OBJECTIVETo explore the patients' genotypes and the mutation spectrum of Tyrosinase (TYR) gene and the effects on protein structure and function in oculocutaneous albinism type 1 (OCA1).

METHODSThe polymerase chain reaction (PCR) and sequencing techniques were applied to amplify and analyze the regions of exon, exonintron and promoter of TYR gene of 15 OCA1 probands and some of their parents. The protein structure and function were forecasted and analyzed by bioinformatics software.

RESULTSSequencing result showed 11 kinds of mutations, including 5 missense mutations (W400L, R299H, E294K, R77Q and K142M), 3 nonsense mutations (R116X, R278X and G295X), 2 insertion mutation (929insC and 232insGGG) and 1 splice site mutation (IVS1-3C > G). The nosogenesis was related to the change of protein structure and function in four pathological mutations.

CONCLUSIONIt seemes that W400L is the frequent mutations, which accounted for about 30.0% in Chinese mainland OCA1 alleles. It is doable to make some reasonable interpretation about TYR gene nosogenesis by bioinformatics method.

Adolescent ; Adult ; Albinism, Oculocutaneous ; genetics ; Child ; Child, Preschool ; China ; DNA Mutational Analysis ; Female ; Genotype ; Humans ; Infant ; Infant, Newborn ; Male ; Monophenol Monooxygenase ; genetics ; Mutation ; Young Adult

OBJECTIVETo evaluate the transfect results of recombinant adenovirus vector carrying tyrosinase gene (Ad-tyr) in vitro by magnetic resonance imaging (MRI) after the Ad-tyr was transfected into HepG2 cell.

METHODSThe Ad-tyr which carried the full-length cDNA of tyrosinase gene was transfected into HepG2 cell. The transfected cells were scan by MRI sequences of T1 weighted image (T1WI) , T2 weighted image (T2WI) , and short time inversion recovery (STIR) to observe the MRI signals of expressed melanin. Masson-Fontana staining was performed to search for melanin granules in transfected cells. Real-time PCR method was used to search for cDNA of tyrosinase gene.

RESULTSAd-tyr was transfected into HepG2 cells and synthesized a large amount of melanin inside. The synthesized melanin of 1 x 10(6) cells which had been transfected by Ad-tyr with the 50, 150, and 300 multiplicity of infection separately were all sufficient to be detected by MRI and showed high signals in MRI T1WI, T2WI, and STIR sequences. The signal intensities of MRI were positively correlated to the amounts of transfected Ad-tyr. The melanin granules were found in HepG2 cells in Masson-Fontana staining. The cDNA amount of tyrosinase gene in transfected HepG2 cells, which was detected by real-time PCR, was remarkably higher than that in nontransfected cells.

CONCLUSIONThe synthesized melanin of HepG2 cells, which controlled by expression of exogenous gene, can be detected by MRI, indicating that the adenovirus vector can efficiently carry the tyrosinase gene into HepG2 cells.

Adenoviridae ; genetics ; metabolism ; Gene Transfer Techniques ; Genetic Vectors ; genetics ; Hep G2 Cells ; Humans ; Magnetic Resonance Imaging ; methods ; Melanins ; analysis ; genetics ; Monophenol Monooxygenase ; biosynthesis ; genetics ; Transfection

In this study, the essential oil from lotus flower extract, including petals and stamens, was assessed with regard to its effects on melanogenesis in human melanocytes. The lotus flower essential oil was shown to stimulate melanin synthesis and tyrosinase activity in a dose-dependent manner. The lotus flower essential oil induced the expression of tyrosinase, microphthalmia-associated transcription factor M (MITF-M), and tyrosinase-related proten-2 (TRP-2) proteins, but not tyrosinase mRNA. Moreover, it increased the phosphorylation of ERK and cAMP response element binding protein (CREB). In order to verify the effective components of the lotus flower oil, its lipid composition was assessed. It was found to be comprised of palmitic acid methyl ester (22.66%), linoleic acid methyl ester (11.16%), palmitoleic acid methyl ester (7.55%) and linolenic acid methyl ester (5.16%). Among these components, palmitic acid methyl ester clearly induced melanogenesis as the result of increased tyrosinase expression, thereby indicating that it may play a role in the regulation of melanin content. Thus, our results indicate that lotus flower oil may prove useful in the development of gray hair prevention agents or tanning reagents.
Blotting, Western ; Cell Proliferation ; Cyclic AMP/metabolism ; Cyclic AMP Response Element-Binding Protein/genetics/metabolism ; Flowers/*chemistry ; Gas Chromatography-Mass Spectrometry ; Humans ; Intramolecular Oxidoreductases/genetics/metabolism ; Lotus/*chemistry ; Melanins/*biosynthesis ; Melanocytes/*drug effects/metabolism ; Microphthalmia-Associated Transcription Factor/genetics/metabolism ; Monophenol Monooxygenase/genetics/metabolism ; Phosphorylation ; Plant Oils/*pharmacology ; RNA, Messenger/genetics/metabolism ; Reverse Transcriptase Polymerase Chain Reaction ; Skin/cytology/drug effects/metabolism

OBJECTIVETo identify the mutations of the tyrosinase gene (TYR) and P gene in patients with oculocutaneous albinism (OCA).

METHODSPolymerase 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.

RESULTSTwo 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.

CONCLUSIONGene diagnosis of OCA can be carried out effectively by combining PCR, DHPLC, DNA sequencing and restriction endonuclease analysis.

Albinism, Oculocutaneous ; genetics ; Base Sequence ; Catechol Oxidase ; genetics ; Child, Preschool ; DNA Mutational Analysis ; Exons ; genetics ; Female ; Hermanski-Pudlak Syndrome ; genetics ; Humans ; Monophenol Monooxygenase ; genetics ; Mutation ; Young Adult