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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

Air audiograms for pure tone audiometry (PTA) of the available subjects with the A1555G mutation.Arrows indicate no responses; Symbols, (X) left ear (O) right ear; dB HL, decibel hearing level.
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pone-0042463-g002: Air audiograms for pure tone audiometry (PTA) of the available subjects with the A1555G mutation.Arrows indicate no responses; Symbols, (X) left ear (O) right ear; dB HL, decibel hearing level.

Mentions: The probands of each pedigree exhibited hearing loss ranging from moderate to profound, with a slope-shaped pattern of audiological evaluation (Fig. 2). Only the probands of the KMT 07 and KMT 09 families had a history of exposure to aminoglycosides. For the age at onset, the probands of the KMT 02 and KMT 08 families showed prelingual hearing loss, and those of the KMT 04, KMT 07 and KMT 09 families had postlingual hearing loss (Table 1).


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)

Air audiograms for pure tone audiometry (PTA) of the available subjects with the A1555G mutation.Arrows indicate no responses; Symbols, (X) left ear (O) right ear; dB HL, decibel hearing level.
© Copyright Policy
Related In: Results  -  Collection

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

pone-0042463-g002: Air audiograms for pure tone audiometry (PTA) of the available subjects with the A1555G mutation.Arrows indicate no responses; Symbols, (X) left ear (O) right ear; dB HL, decibel hearing level.
Mentions: The probands of each pedigree exhibited hearing loss ranging from moderate to profound, with a slope-shaped pattern of audiological evaluation (Fig. 2). Only the probands of the KMT 07 and KMT 09 families had a history of exposure to aminoglycosides. For the age at onset, the probands of the KMT 02 and KMT 08 families showed prelingual hearing loss, and those of the KMT 04, KMT 07 and KMT 09 families had postlingual hearing loss (Table 1).

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