It has be known that ventilatory dysfunction of the eustachian
tube and ear gas exchange failure in the middle ear are extrinsic
factors in middle ear cholesteatoma. However,
the relationship between human genes such as intrinsic factor
and middle ear cholesteatoma are not well understood. Human
earwax shows wet and dry types. Yoshiura reported
that one single-nucleotide polymorphism (SNP) in the human
ATP-binding cassette C11 (ABCC11) could be a determinant
of the human ear wax type. The G/G and G/A genotypes
correspond to wet earwax, whereas. The A/A genotype corresponds
to dry earwax. Ishikawa demonstrated the allele
frequencies of wet earwax with alleleG (Gly180) and dry
earwax with alleleA (Arg 180) among different ethnic populations.
Africans and Europeans showed a high frequency of
80-100% wet earwax. I n contrast, east Asians (Japanese, Chinese,
Korean, Mongolian) showed a low frequency of 0-30%.
The incidence of middle ear cholesteatoma in Europeans with
a high frequency of wet earwax was higher than in Japanese with a low frequency of wet earwax. Therefore, wet considered
that the earwax phenotype could be related to middle
ear cholesteatoma in Japan.
The earwax phenotype of 40 patients with middle ear cholesteatoma
were decided earwax in healthy side and distant
location from cholesteatoma by inspection. (Figure1). The
present research was approved by the Juntendo University
Committee for the Ethical Issues of human genome.
In Table1, the frequencies of dry earwax and wet earwax were
62.5% (25/40) and 37.5% (15/40), respectively. The incidence
of cases with bilateral middle ear cholesteatoma (including past history of surgery for middle ear cholesteatoma) in the
group with wet earwax was 66.7% (10 /15), which was significantly
higher than in the dry earwax group, 24.0% (6/25) P <
0.05. Clinically advance grades of middle ear cholesteatoma
showed no difference between dry earwax cases and wet earwax
cases.
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