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Clinical and biochemical effects of the E139K missense mutation in the TIMP3 gene, associated with Sorsby fundus dystrophy.

Saihan Z, Li Z, Rice J, Rana NA, Ramsden S, Schlottmann PG, Jenkins SA, Blyth C, Black GC, McKie N, Webster AR - Mol. Vis. (2009)

Bottom Line: The TIMP3 p.E139K mutation is another cause of SFD.It is the second TIMP3 sequence variant reported that does not affect the number of cysteine residues in the mutant protein yet dimerizes in vitro.The clinical presentation of this family is in keeping with previous clinical reports of this disorder.

View Article: PubMed Central - PubMed

Affiliation: Moorfields Eye Hospital, London, UK. z.saihan@ucl.ac.uk

ABSTRACT

Purpose: To determine the phenotypic and biochemical characteristics of the p.E139K missense variant in tissue inhibitor of metalloproteinase 3 (TIMP3) associated with Sorsby fundus dystrophy (SFD).

Methods: The coding regions and adjacent intronic sequence of TIMP3 were amplified by polymerase chain reaction and then analyzed by bidirectional sequencing. Allele-specific PCR was used to determine the minimum allele frequency of the mutant allele in ethnically matched controls. Clinical examination and imaging of affected individuals with color fundus photography, scanning laser ophthalmoscope (fundal autofluorescence), and optical coherence tomography was performed. A mutant construct of the TIMP3 protein was created and expressed in human retinal pigment epithelium (ARPE19) cells, which were then assayed for oligomerization and intrinsic matrix metalloproteinase (MMP) inhibitory activity.

Results: Three affected individuals from a family of Welsh origin each harbored one allele of the TIMP3 missense variant c.415 G>A, (p.E139K), which was not identified in 534 ethnically matched control chromosomes and thus presumed pathogenic. The mutant protein was shown to dimerize in culture cells and retain its MMP inhibitory activity. Retinal examination was variable between eyes of affected individuals and between family members. Drusen-like deposits were common to all three affected individuals and yellow subretinal deposits, exudative maculopathy, and geographic atrophy were also observed. Optical coherence tomography (OCT) images of affected individuals demonstrated hyperreflectivity of the RPE-photoreceptor-choroid complex.

Conclusions: The TIMP3 p.E139K mutation is another cause of SFD. It is the second TIMP3 sequence variant reported that does not affect the number of cysteine residues in the mutant protein yet dimerizes in vitro. The clinical presentation of this family is in keeping with previous clinical reports of this disorder.

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Related in: MedlinePlus

Pedigree of family showing genotypes for the c.415 G>A sequence variant in TIMP3. Affected individuals are shown in black. Genotypes for the c.415 G>A sequence variant (p.E139K) in TIMP3 are shown underneath. Abbreviations: G/G represents homozygous wild type and G/A represents heterozygous for the mutant allele.
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f1: Pedigree of family showing genotypes for the c.415 G>A sequence variant in TIMP3. Affected individuals are shown in black. Genotypes for the c.415 G>A sequence variant (p.E139K) in TIMP3 are shown underneath. Abbreviations: G/G represents homozygous wild type and G/A represents heterozygous for the mutant allele.

Mentions: A three-generation British family of Welsh origin with an autosomal dominant history of retinal degeneration was referred to the Medical Retina clinic at Moorfields Eye Hospital (Figure 1). Three affected and two unaffected family members were available for study. The protocol of the study adhered to the provisions of the Declaration of Helsinki and was approved by the Moorfields Eye Hospital Ethics Committee. Genomic DNA was isolated from whole blood using an extraction kit (GE Healthcare Ltd, Buckinghamshire, UK). For the three affected individuals, full medical histories were taken and ophthalmic examination undertaken, including LogMAR visual acuities, slit-lamp biomicroscopy, color fundus photography, optical coherence tomography using 6-mm-length scans centered on the fovea (Stratus optical coherence tomography-OCT; Carl Zeiss Meditec, Dublin, CA), and fundus autofluorescence imaging, performed with a confocal scanning laser ophthalmoscope (cSLO, HRA, Heidelberg, Germany).


Clinical and biochemical effects of the E139K missense mutation in the TIMP3 gene, associated with Sorsby fundus dystrophy.

Saihan Z, Li Z, Rice J, Rana NA, Ramsden S, Schlottmann PG, Jenkins SA, Blyth C, Black GC, McKie N, Webster AR - Mol. Vis. (2009)

Pedigree of family showing genotypes for the c.415 G>A sequence variant in TIMP3. Affected individuals are shown in black. Genotypes for the c.415 G>A sequence variant (p.E139K) in TIMP3 are shown underneath. Abbreviations: G/G represents homozygous wild type and G/A represents heterozygous for the mutant allele.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2697491&req=5

f1: Pedigree of family showing genotypes for the c.415 G>A sequence variant in TIMP3. Affected individuals are shown in black. Genotypes for the c.415 G>A sequence variant (p.E139K) in TIMP3 are shown underneath. Abbreviations: G/G represents homozygous wild type and G/A represents heterozygous for the mutant allele.
Mentions: A three-generation British family of Welsh origin with an autosomal dominant history of retinal degeneration was referred to the Medical Retina clinic at Moorfields Eye Hospital (Figure 1). Three affected and two unaffected family members were available for study. The protocol of the study adhered to the provisions of the Declaration of Helsinki and was approved by the Moorfields Eye Hospital Ethics Committee. Genomic DNA was isolated from whole blood using an extraction kit (GE Healthcare Ltd, Buckinghamshire, UK). For the three affected individuals, full medical histories were taken and ophthalmic examination undertaken, including LogMAR visual acuities, slit-lamp biomicroscopy, color fundus photography, optical coherence tomography using 6-mm-length scans centered on the fovea (Stratus optical coherence tomography-OCT; Carl Zeiss Meditec, Dublin, CA), and fundus autofluorescence imaging, performed with a confocal scanning laser ophthalmoscope (cSLO, HRA, Heidelberg, Germany).

Bottom Line: The TIMP3 p.E139K mutation is another cause of SFD.It is the second TIMP3 sequence variant reported that does not affect the number of cysteine residues in the mutant protein yet dimerizes in vitro.The clinical presentation of this family is in keeping with previous clinical reports of this disorder.

View Article: PubMed Central - PubMed

Affiliation: Moorfields Eye Hospital, London, UK. z.saihan@ucl.ac.uk

ABSTRACT

Purpose: To determine the phenotypic and biochemical characteristics of the p.E139K missense variant in tissue inhibitor of metalloproteinase 3 (TIMP3) associated with Sorsby fundus dystrophy (SFD).

Methods: The coding regions and adjacent intronic sequence of TIMP3 were amplified by polymerase chain reaction and then analyzed by bidirectional sequencing. Allele-specific PCR was used to determine the minimum allele frequency of the mutant allele in ethnically matched controls. Clinical examination and imaging of affected individuals with color fundus photography, scanning laser ophthalmoscope (fundal autofluorescence), and optical coherence tomography was performed. A mutant construct of the TIMP3 protein was created and expressed in human retinal pigment epithelium (ARPE19) cells, which were then assayed for oligomerization and intrinsic matrix metalloproteinase (MMP) inhibitory activity.

Results: Three affected individuals from a family of Welsh origin each harbored one allele of the TIMP3 missense variant c.415 G>A, (p.E139K), which was not identified in 534 ethnically matched control chromosomes and thus presumed pathogenic. The mutant protein was shown to dimerize in culture cells and retain its MMP inhibitory activity. Retinal examination was variable between eyes of affected individuals and between family members. Drusen-like deposits were common to all three affected individuals and yellow subretinal deposits, exudative maculopathy, and geographic atrophy were also observed. Optical coherence tomography (OCT) images of affected individuals demonstrated hyperreflectivity of the RPE-photoreceptor-choroid complex.

Conclusions: The TIMP3 p.E139K mutation is another cause of SFD. It is the second TIMP3 sequence variant reported that does not affect the number of cysteine residues in the mutant protein yet dimerizes in vitro. The clinical presentation of this family is in keeping with previous clinical reports of this disorder.

Show MeSH
Related in: MedlinePlus