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Molecular and clinical characterization of the variable phenotype in Korean families with hearing loss associated with the mitochondrial A1555G mutation.

Bae JW, Kim DB, Choi JY, Park HJ, Lee JD, Hur DG, Bae SH, Jung da J, Lee SH, Kim UK, Lee KY - PLoS ONE (2012)

Bottom Line: These results were higher than the 29.8% penetrance that was previously reported in a Chinese population but similar to the 65.4% and 54.1% penetrance observed in a large Arab-Israeli population and nineteen Spanish pedigrees, respectively.The mtDNA variants that may act as modifier factors were also found to be similar to the Chinese population.This result suggests that both the ethnic background and environmental factors lead to a variable phenotype of the A1555G mutation.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, College of Natural Sciences, Kyungpook National University, Daegu, South Korea.

ABSTRACT
Hearing loss, which is genetically heterogeneous, can be caused by mutations in the mitochondrial DNA (mtDNA). The A1555G mutation of the 12S ribosomal RNA (rRNA) gene in the mtDNA has been associated with both aminoglycoside-induced and non-syndromic hearing loss in many ethnic populations. Here, we report for the first time the clinical and genetic characterization of nine Korean pedigrees with aminoglycoside-induced and non-syndromic hearing loss. These Korean families carry in the A1555G mutation of 12S rRNA gene and exhibit variable penetrance and expressivity of hearing loss. Specifically, the penetrance of hearing loss in these families ranged between 28.6% and 75%, with an average of 60.8%. These results were higher than the 29.8% penetrance that was previously reported in a Chinese population but similar to the 65.4% and 54.1% penetrance observed in a large Arab-Israeli population and nineteen Spanish pedigrees, respectively. The mutational analysis of the complete mtDNA genome in these families showed that the haplogroups of the Korean population, which belongs to the eastern Asian population, were similar to those of the Chinese population but different from the Spanish population, which belongs to the European-Caucasian population. The mtDNA variants that may act as modifier factors were also found to be similar to the Chinese population. Although the mtDNA haplogroups and variants were similar to the eastern Asian population, we did find some differing phenotypes, although some subjects had the same variants. This result suggests that both the ethnic background and environmental factors lead to a variable phenotype of the A1555G mutation.

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Related in: MedlinePlus

Eight Korean pedigrees presenting with nonsyndromic hearing loss were carrying the A1555G mtDNA mutation.Hearing-impaired individuals are indicated by filled symbols. Arrows denote probands. Subjects used for whole mtDNA sequence analysis are indicated by asterisks. Subjects used for the A1555G mutation screening are underlined.
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pone-0042463-g001: Eight Korean pedigrees presenting with nonsyndromic hearing loss were carrying the A1555G mtDNA mutation.Hearing-impaired individuals are indicated by filled symbols. Arrows denote probands. Subjects used for whole mtDNA sequence analysis are indicated by asterisks. Subjects used for the A1555G mutation screening are underlined.

Mentions: We performed a sequence analysis to identify the A1555G mutation in 281 Korean unrelated subjects with non-syndromic hearing loss, excluding those subjects with complete autosomal recessive inheritance patterns. First, the genomic DNA of each subject was amplified using the appropriate primers, and these products were digested using BsmAI and analyzed on a 2% agarose gel. Nine of the subjects had the A1555G mutation, which was further confirmed using PCR and subsequent DNA sequence analysis. Next, we performed mutational screening for the A1555G mutation in the available matrilineal relatives of those subjects except for KMT09 family who was not available for pedigree data. The A1555G mutation was detected in all matrilineal relatives. The penetrance of hearing loss (affected matrilineal relatives/total matrilineal relatives) of the eight pedigrees ranged from 28.6% to 75%, with an average of 60.8% (Fig. 1) [17], [19], [23], [24].


Molecular and clinical characterization of the variable phenotype in Korean families with hearing loss associated with the mitochondrial A1555G mutation.

Bae JW, Kim DB, Choi JY, Park HJ, Lee JD, Hur DG, Bae SH, Jung da J, Lee SH, Kim UK, Lee KY - PLoS ONE (2012)

Eight Korean pedigrees presenting with nonsyndromic hearing loss were carrying the A1555G mtDNA mutation.Hearing-impaired individuals are indicated by filled symbols. Arrows denote probands. Subjects used for whole mtDNA sequence analysis are indicated by asterisks. Subjects used for the A1555G mutation screening are underlined.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3412860&req=5

pone-0042463-g001: Eight Korean pedigrees presenting with nonsyndromic hearing loss were carrying the A1555G mtDNA mutation.Hearing-impaired individuals are indicated by filled symbols. Arrows denote probands. Subjects used for whole mtDNA sequence analysis are indicated by asterisks. Subjects used for the A1555G mutation screening are underlined.
Mentions: We performed a sequence analysis to identify the A1555G mutation in 281 Korean unrelated subjects with non-syndromic hearing loss, excluding those subjects with complete autosomal recessive inheritance patterns. First, the genomic DNA of each subject was amplified using the appropriate primers, and these products were digested using BsmAI and analyzed on a 2% agarose gel. Nine of the subjects had the A1555G mutation, which was further confirmed using PCR and subsequent DNA sequence analysis. Next, we performed mutational screening for the A1555G mutation in the available matrilineal relatives of those subjects except for KMT09 family who was not available for pedigree data. The A1555G mutation was detected in all matrilineal relatives. The penetrance of hearing loss (affected matrilineal relatives/total matrilineal relatives) of the eight pedigrees ranged from 28.6% to 75%, with an average of 60.8% (Fig. 1) [17], [19], [23], [24].

Bottom Line: These results were higher than the 29.8% penetrance that was previously reported in a Chinese population but similar to the 65.4% and 54.1% penetrance observed in a large Arab-Israeli population and nineteen Spanish pedigrees, respectively.The mtDNA variants that may act as modifier factors were also found to be similar to the Chinese population.This result suggests that both the ethnic background and environmental factors lead to a variable phenotype of the A1555G mutation.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, College of Natural Sciences, Kyungpook National University, Daegu, South Korea.

ABSTRACT
Hearing loss, which is genetically heterogeneous, can be caused by mutations in the mitochondrial DNA (mtDNA). The A1555G mutation of the 12S ribosomal RNA (rRNA) gene in the mtDNA has been associated with both aminoglycoside-induced and non-syndromic hearing loss in many ethnic populations. Here, we report for the first time the clinical and genetic characterization of nine Korean pedigrees with aminoglycoside-induced and non-syndromic hearing loss. These Korean families carry in the A1555G mutation of 12S rRNA gene and exhibit variable penetrance and expressivity of hearing loss. Specifically, the penetrance of hearing loss in these families ranged between 28.6% and 75%, with an average of 60.8%. These results were higher than the 29.8% penetrance that was previously reported in a Chinese population but similar to the 65.4% and 54.1% penetrance observed in a large Arab-Israeli population and nineteen Spanish pedigrees, respectively. The mutational analysis of the complete mtDNA genome in these families showed that the haplogroups of the Korean population, which belongs to the eastern Asian population, were similar to those of the Chinese population but different from the Spanish population, which belongs to the European-Caucasian population. The mtDNA variants that may act as modifier factors were also found to be similar to the Chinese population. Although the mtDNA haplogroups and variants were similar to the eastern Asian population, we did find some differing phenotypes, although some subjects had the same variants. This result suggests that both the ethnic background and environmental factors lead to a variable phenotype of the A1555G mutation.

Show MeSH
Related in: MedlinePlus