Functional assessment of tyrosinase variants identified in individuals with albinism is essential for unequivocal determination of genotype-to-phenotype correlation
IR@IICB: CSIR-Indian Institute of Chemical Biology, Kolkata
View Archive Info| Field | Value | |
| Title |
Functional assessment of tyrosinase variants identified in
individuals with albinism is essential for unequivocal
determination of genotype-to-phenotype correlation
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| Creator |
Mondal, M
Sengupta, M Ray, Kunal |
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| Subject |
Molecular & Human Genetics
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| Description |
Oculocutaneous albinism type 1 (OCA1), caused by pathogenic variations in the tyrosinase gene (TYR), is the most frequent and severe form of hypopigmentary disorder worldwide. While OCA1A manifests as a complete loss of melanin pigment, patients with OCA1B show residual pigmentation of the skin, hair and eyes. Limited experimental evidence suggests retention of TYR in
the endoplasmic reticulum (ER) causes OCA1 pathogenesis. However, a comprehensive functional analysis of TYR missense variations and correlation with genotype
is lacking. Objectives Functional characterization of nonsynonymous tyrosinase variants in patients with OCA1 reported in the Albinism Database, dbSNP and the published
literature, and an attempt to correlate them with reported and predicted phenotypes. Thirty-four reported missense variants of TYR were subcloned by sitedirected
mutagenesis, and the dual-enzyme activities of the variant proteins were compared with the wild-type. The degree of ER retention was also checked for each of the variants through endoglycosidase H (Endo H) digestion followed by
immunoprecipitation and densitometric analysis. Functional studies revealed one reported OCA1A variation with nearly100% enzyme activity, 10 OCA1B variants lacking any enzyme activity, eight nonsynonymous single-nucleotide polymorphisms (SNPs) with ~30–70% of enzyme activity, and three SNPs that completely lacked activity altogether. The
Endo H assay corroborated these results.Loss of enzyme activity of TYR variants was completely in agreement
with ER retention across all variants examined. The results of the assay clearly established that determination of the biological activity of identified variants in patients with OCA is essential to correlate the identified suspect genotype with the obvious phenotype of the disease.
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| Publisher |
Blackwell Publishing
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| Date |
2016
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| Type |
Article
PeerReviewed |
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| Format |
application/pdf
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| Identifier |
http://www.eprints.iicb.res.in/2597/1/British_Journal_of_Dermatology_(2016)_175%2C.pdf
Mondal, M and Sengupta, M and Ray, Kunal (2016) Functional assessment of tyrosinase variants identified in individuals with albinism is essential for unequivocal determination of genotype-to-phenotype correlation. British Journal Of Dermatology, 175. pp. 1232-1242. |
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| Relation |
http://dx.doi.org/10.1111/bjd.14977
http://www.eprints.iicb.res.in/2597/ |
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