Within one individual, the presence of two or more cell populations with different genotypes, derived from a post-zygotic mutation, ranging from single-nucleotide to large segmental variations.
Previous studies examining the frequency of p16 mutation in esophageal cancer have focused primarily upon SCC in surgical resections, with reported frequencies of mutation ranging from 0% to 52%, with most studies reporting 15 20% [4], [14], [30].
We found that the frequency of incorporating this mutation ranged from 0 - 100%.
The MIC required for isolates with this mutation ranges from 1 μg/mL to 4 μg/mL.
Interestingly, there is a wide disparity of clinical phenotypes, even among patients with the same mutation, ranging from being asymptomatic to death of newborns.
12, 13 In this study, the frequency of BRAF and NRAS mutations (47%/33%) was consistent with that reported in previous studies in which BRAF mutation ranged from 22%to72%2% and NRAS mutation ranged from 0%to50%0% 4, 14, 15 and, in agreement with the literature, the majority of BRAF mutations were in codon 600.
In Japan, the prevalence of K-ras mutation ranged from 90 to 100%, whereas in the West it was relatively low, ranging from 65 to 70% in Europe and 85% in USA.
While the hCHK2 1100delC mutation clearly encodes a nonfunctional protein, the tumour spectrum initially reported with this germline mutation ranges from classic LFS [ 4] to atypical Li–Fraumeni-like syndrome, with a predominance of early-onset breast cancer [ 9].
Recent studies have shown the frequency of codon 146 mutation ranging from 1.0% to 4.0% in CRCs [ 13- 15], however, KRAS mutation at codon 146 is related to resistance to cetuximab plus irinotecan and is recognized to be an important mutation of KRAS gene [ 13].
Specifically, in a study involving 30 patients with vulvar and vaginal melanomas, BRAF and NRAS mutations exhibited a 7%and10%0% frequency, respectively [ 24], while similar low frequencies of BRAF mutation ranging from 0%too 12.5% have been detected in other studies [ 26, 27, 37].
