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Macular corneal dystrophy in a Chinese family related with novel mutations of CHST6.

Dang X, Zhu Q, Wang L, Su H, Lin H, Zhou N, Liang T, Wang Z, Huang S, Ren Q, Qi Y - Mol. Vis. (2009)

Bottom Line: The two transversions resulted in the substitution of a stop codon for glutamine at codon 298 (p.Q298X) and a missense mutation at codon 358, tyrosine to histidine (p.Y358H).Those novel compound heterozygous mutations were thought to contribute to the loss of CHST6 function, which induced the abnormal metabolism of keratan sulfate (KS) that deposited in the corneal stroma.It could be proved by the observation of a positive stain reaction and the enlarged collagen fibers as well as hyperplastic fibroblasts under microscopes.

View Article: PubMed Central - PubMed

Affiliation: Department of Ophthalmology, the Second Affiliated Hospital of Harbin Medical University, Harbin, Heilongjiang, China.

ABSTRACT

Purpose: To identify mutations in the carbohydrate sulfotransferase gene (CHST6) for a Chinese family with macular corneal dystrophy (MCD) and to investigate the histopathological changes in the affected cornea.

Methods: A corneal button of the proband was obtained by penetrating keratoplasty. The half button and ultrathin sections from the other half button were examined with special stains under a light microscope (LM) and an electron microscope (EM) separately. Genomic DNA was extracted from peripheral blood of 11 family members, and the coding region of CHST6 was amplified by the polymerase chain reaction (PCR) method. The PCR products were analyzed by direct sequencing and restriction enzyme digestion.

Results: The positive reaction to colloidal iron stain (extracellular blue accumulations in the stroma) was detected under light microscopy. Transmission electron microscopy revealed the enlargement of smooth endoplasmic reticulum and the presence of intracytoplasmic vacuoles. The compound heterozygous mutations, c.892C>T and c.1072T>C, were identified in exon 3 of CHST6 in three patients. The two transversions resulted in the substitution of a stop codon for glutamine at codon 298 (p.Q298X) and a missense mutation at codon 358, tyrosine to histidine (p.Y358H). The six unaffected family individuals carried alternative heterozygous mutations. These two mutations were not detected in any of the 100 control subjects.

Conclusions: Those novel compound heterozygous mutations were thought to contribute to the loss of CHST6 function, which induced the abnormal metabolism of keratan sulfate (KS) that deposited in the corneal stroma. It could be proved by the observation of a positive stain reaction and the enlarged collagen fibers as well as hyperplastic fibroblasts under microscopes.

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Related in: MedlinePlus

PvuII digestion of PCR products for the c.892C>T transition. PCR products in individuals with the c.892C>T transition were digested into 153 bp and 173 bp and into only 153 bp in individuals without the c.892C>T transition. A: Members of the Chinese family with MCD. PCR products from individuals II:2, III:1, III:2, III:4, III:6 and IV:1 with c.892C>T transition were digested into 153bp and 173bp, other members without c.892C>T transition only had a 153bp segment. B :Part of 100 control subjects. Control subjects without c.892C>T transition only had a 153bp segment. M indicates DNA ladder, U indicates undigested PCR product, and P indicates one patient with MCD in the Chinese family.
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f6: PvuII digestion of PCR products for the c.892C>T transition. PCR products in individuals with the c.892C>T transition were digested into 153 bp and 173 bp and into only 153 bp in individuals without the c.892C>T transition. A: Members of the Chinese family with MCD. PCR products from individuals II:2, III:1, III:2, III:4, III:6 and IV:1 with c.892C>T transition were digested into 153bp and 173bp, other members without c.892C>T transition only had a 153bp segment. B :Part of 100 control subjects. Control subjects without c.892C>T transition only had a 153bp segment. M indicates DNA ladder, U indicates undigested PCR product, and P indicates one patient with MCD in the Chinese family.

Mentions: PCR products from 100 control subjects were analyzed by the same two restriction enzymes, but no mutation segments were found among them (Figure 6, Figure 7).


Macular corneal dystrophy in a Chinese family related with novel mutations of CHST6.

Dang X, Zhu Q, Wang L, Su H, Lin H, Zhou N, Liang T, Wang Z, Huang S, Ren Q, Qi Y - Mol. Vis. (2009)

PvuII digestion of PCR products for the c.892C>T transition. PCR products in individuals with the c.892C>T transition were digested into 153 bp and 173 bp and into only 153 bp in individuals without the c.892C>T transition. A: Members of the Chinese family with MCD. PCR products from individuals II:2, III:1, III:2, III:4, III:6 and IV:1 with c.892C>T transition were digested into 153bp and 173bp, other members without c.892C>T transition only had a 153bp segment. B :Part of 100 control subjects. Control subjects without c.892C>T transition only had a 153bp segment. M indicates DNA ladder, U indicates undigested PCR product, and P indicates one patient with MCD in the Chinese family.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2666773&req=5

f6: PvuII digestion of PCR products for the c.892C>T transition. PCR products in individuals with the c.892C>T transition were digested into 153 bp and 173 bp and into only 153 bp in individuals without the c.892C>T transition. A: Members of the Chinese family with MCD. PCR products from individuals II:2, III:1, III:2, III:4, III:6 and IV:1 with c.892C>T transition were digested into 153bp and 173bp, other members without c.892C>T transition only had a 153bp segment. B :Part of 100 control subjects. Control subjects without c.892C>T transition only had a 153bp segment. M indicates DNA ladder, U indicates undigested PCR product, and P indicates one patient with MCD in the Chinese family.
Mentions: PCR products from 100 control subjects were analyzed by the same two restriction enzymes, but no mutation segments were found among them (Figure 6, Figure 7).

Bottom Line: The two transversions resulted in the substitution of a stop codon for glutamine at codon 298 (p.Q298X) and a missense mutation at codon 358, tyrosine to histidine (p.Y358H).Those novel compound heterozygous mutations were thought to contribute to the loss of CHST6 function, which induced the abnormal metabolism of keratan sulfate (KS) that deposited in the corneal stroma.It could be proved by the observation of a positive stain reaction and the enlarged collagen fibers as well as hyperplastic fibroblasts under microscopes.

View Article: PubMed Central - PubMed

Affiliation: Department of Ophthalmology, the Second Affiliated Hospital of Harbin Medical University, Harbin, Heilongjiang, China.

ABSTRACT

Purpose: To identify mutations in the carbohydrate sulfotransferase gene (CHST6) for a Chinese family with macular corneal dystrophy (MCD) and to investigate the histopathological changes in the affected cornea.

Methods: A corneal button of the proband was obtained by penetrating keratoplasty. The half button and ultrathin sections from the other half button were examined with special stains under a light microscope (LM) and an electron microscope (EM) separately. Genomic DNA was extracted from peripheral blood of 11 family members, and the coding region of CHST6 was amplified by the polymerase chain reaction (PCR) method. The PCR products were analyzed by direct sequencing and restriction enzyme digestion.

Results: The positive reaction to colloidal iron stain (extracellular blue accumulations in the stroma) was detected under light microscopy. Transmission electron microscopy revealed the enlargement of smooth endoplasmic reticulum and the presence of intracytoplasmic vacuoles. The compound heterozygous mutations, c.892C>T and c.1072T>C, were identified in exon 3 of CHST6 in three patients. The two transversions resulted in the substitution of a stop codon for glutamine at codon 298 (p.Q298X) and a missense mutation at codon 358, tyrosine to histidine (p.Y358H). The six unaffected family individuals carried alternative heterozygous mutations. These two mutations were not detected in any of the 100 control subjects.

Conclusions: Those novel compound heterozygous mutations were thought to contribute to the loss of CHST6 function, which induced the abnormal metabolism of keratan sulfate (KS) that deposited in the corneal stroma. It could be proved by the observation of a positive stain reaction and the enlarged collagen fibers as well as hyperplastic fibroblasts under microscopes.

Show MeSH
Related in: MedlinePlus