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A Novel Insertion Variant of CRYGD Is Associated with Congenital Nuclear Cataract in a Chinese Family.

Zhuang X, Wang L, Song Z, Xiao W - PLoS ONE (2015)

Bottom Line: A significantly reduced solubility was observed for this mutant.We have identified a novel mutation, c.451_452insGACT, in CRYGD, which is associated with nuclear cataract.The mutant protein, with loss of solubility and localization to the nucleus, is hypothesized to be the major cause of cataract in these patients.

View Article: PubMed Central - PubMed

Affiliation: Department of Ophthalmology, Shengjing Hospital, China Medical University, Shenyang, China; Department of Ophthalmology, The Fourth People's Hospital of Shenyang, Shenyang, China.

ABSTRACT

Objective: To investigate a novel insertion variant of CRYGD identified in a Chinese family with nuclear congenital cataract.

Methods: A Chinese family with congenital nuclear cataract was recruited for the mutational screening of candidate genes by direct sequencing. Recombinant N-terminal Myc tagged wildtype or mutant CRYGD was expressed in HEK293T cells. The expression pattern, protein solubility and subcellular distribution were analyzed by western blotting and immunofluorescence.

Principal findings: A novel insertion variant, c.451_452insGACT, in CRYGD was identified in the patients. It causes a frameshift and a premature termination of the polypeptide to become Y151*. A significantly reduced solubility was observed for this mutant. Unlike wildtype CRYGD, which existed mainly in the cytoplasm, Y151* was mis-located in the nucleus.

Conclusions: We have identified a novel mutation, c.451_452insGACT, in CRYGD, which is associated with nuclear cataract. This is the first insertion mutation of CRYGD found to cause autosomal dominant congenital cataract. The mutant protein, with loss of solubility and localization to the nucleus, is hypothesized to be the major cause of cataract in these patients.

No MeSH data available.


Related in: MedlinePlus

Confirmation of the c.451_452insGACT (p.Tyr151*) insertion mutation of CRYGD.(A) Sequence chromatogram showing the heterozygous c.451_452insGACT insertion mutation of CRYGD in the proband. The mutation was numbered according to GenBank NM_006891.3. (B) Polyacrylamide gel electrophoresis showing different sizes of the PCR fragments in the pedigree. The 134 bp and 130 bp fragments were amplified from affected and unaffected chromosome, respectively. (C) Protein alignment of mammalian samples showing that the regions around the mutation are highly conserved. Numbers on left and right indicate the position of this fragment. The position of the mutant is marked by a black triangle.
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pone.0131471.g002: Confirmation of the c.451_452insGACT (p.Tyr151*) insertion mutation of CRYGD.(A) Sequence chromatogram showing the heterozygous c.451_452insGACT insertion mutation of CRYGD in the proband. The mutation was numbered according to GenBank NM_006891.3. (B) Polyacrylamide gel electrophoresis showing different sizes of the PCR fragments in the pedigree. The 134 bp and 130 bp fragments were amplified from affected and unaffected chromosome, respectively. (C) Protein alignment of mammalian samples showing that the regions around the mutation are highly conserved. Numbers on left and right indicate the position of this fragment. The position of the mutant is marked by a black triangle.

Mentions: Mutation screenings were performed for all six candidate crystallin genes, and a heterozygous variant, c.451_452insGACT, was identified in exon 3 of CRYGD (Fig 2A). The variant led to the substitution of a newly formed stop codon for a phylogenetically conserved tyrosine residue (p.Tyr151*) (Fig 2B), and was only identified in the affected individuals. With the exception of several nonpathogenic SNPs, no other variants were detected. On polyacrylamide gel electrophoresis, the variant was confirmed in all affected individuals but was not detected in unaffected family members or 103 unrelated Chinese controls (Fig 2C).


A Novel Insertion Variant of CRYGD Is Associated with Congenital Nuclear Cataract in a Chinese Family.

Zhuang X, Wang L, Song Z, Xiao W - PLoS ONE (2015)

Confirmation of the c.451_452insGACT (p.Tyr151*) insertion mutation of CRYGD.(A) Sequence chromatogram showing the heterozygous c.451_452insGACT insertion mutation of CRYGD in the proband. The mutation was numbered according to GenBank NM_006891.3. (B) Polyacrylamide gel electrophoresis showing different sizes of the PCR fragments in the pedigree. The 134 bp and 130 bp fragments were amplified from affected and unaffected chromosome, respectively. (C) Protein alignment of mammalian samples showing that the regions around the mutation are highly conserved. Numbers on left and right indicate the position of this fragment. The position of the mutant is marked by a black triangle.
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4493073&req=5

pone.0131471.g002: Confirmation of the c.451_452insGACT (p.Tyr151*) insertion mutation of CRYGD.(A) Sequence chromatogram showing the heterozygous c.451_452insGACT insertion mutation of CRYGD in the proband. The mutation was numbered according to GenBank NM_006891.3. (B) Polyacrylamide gel electrophoresis showing different sizes of the PCR fragments in the pedigree. The 134 bp and 130 bp fragments were amplified from affected and unaffected chromosome, respectively. (C) Protein alignment of mammalian samples showing that the regions around the mutation are highly conserved. Numbers on left and right indicate the position of this fragment. The position of the mutant is marked by a black triangle.
Mentions: Mutation screenings were performed for all six candidate crystallin genes, and a heterozygous variant, c.451_452insGACT, was identified in exon 3 of CRYGD (Fig 2A). The variant led to the substitution of a newly formed stop codon for a phylogenetically conserved tyrosine residue (p.Tyr151*) (Fig 2B), and was only identified in the affected individuals. With the exception of several nonpathogenic SNPs, no other variants were detected. On polyacrylamide gel electrophoresis, the variant was confirmed in all affected individuals but was not detected in unaffected family members or 103 unrelated Chinese controls (Fig 2C).

Bottom Line: A significantly reduced solubility was observed for this mutant.We have identified a novel mutation, c.451_452insGACT, in CRYGD, which is associated with nuclear cataract.The mutant protein, with loss of solubility and localization to the nucleus, is hypothesized to be the major cause of cataract in these patients.

View Article: PubMed Central - PubMed

Affiliation: Department of Ophthalmology, Shengjing Hospital, China Medical University, Shenyang, China; Department of Ophthalmology, The Fourth People's Hospital of Shenyang, Shenyang, China.

ABSTRACT

Objective: To investigate a novel insertion variant of CRYGD identified in a Chinese family with nuclear congenital cataract.

Methods: A Chinese family with congenital nuclear cataract was recruited for the mutational screening of candidate genes by direct sequencing. Recombinant N-terminal Myc tagged wildtype or mutant CRYGD was expressed in HEK293T cells. The expression pattern, protein solubility and subcellular distribution were analyzed by western blotting and immunofluorescence.

Principal findings: A novel insertion variant, c.451_452insGACT, in CRYGD was identified in the patients. It causes a frameshift and a premature termination of the polypeptide to become Y151*. A significantly reduced solubility was observed for this mutant. Unlike wildtype CRYGD, which existed mainly in the cytoplasm, Y151* was mis-located in the nucleus.

Conclusions: We have identified a novel mutation, c.451_452insGACT, in CRYGD, which is associated with nuclear cataract. This is the first insertion mutation of CRYGD found to cause autosomal dominant congenital cataract. The mutant protein, with loss of solubility and localization to the nucleus, is hypothesized to be the major cause of cataract in these patients.

No MeSH data available.


Related in: MedlinePlus