The transition of IDHmut lower grade gliomas to grade IV gliomas involves loss of PTEN and dysregulation of cell cycle regulators, in addition to an apparent higher frequency of chromosomal instability and/or chromothripsis.
One study reported infrequent microsatellite instable gastric cancers in South African patients[ 34] which is in contrast with our findings which show a higher frequency of microsatellite instability in gastric cancers from SA patients compared to UK patients.
However, there is a significantly higher frequency of the CA-repeat instability in breast cancer (42.5%; 17 out of 40) (Richard et al, 2000).
Gastric cancers from SA patients show higher frequencies of microsatellite instability and different patterns of chromosomal aberrations compared to gastric cancers from UK patients.
To rule out that tumors from South African patients cluster together by hierarchical cluster analysis due to the fact that these tumors show higher frequencies of microsatellite instability, only microsatellite stable gastric cancers were included in the hierarchical cluster analysis.
Mucinous adenocarcinoma and AIM had higher frequency of proximal location and microsatellite instability, but lower frequency of angiolymphatic invasion.
Loss of TP53 function may result in increased genetic instability with higher frequency of mutations, chromosomal abnormalities, gene amplifications, LOH and abnormal chromosome segregation (Fukasawa et al, 1996; Morris, 2002).
Left and right CRCs have been suggested to be different clinicopathological entities [ 39, 40] Right CRCs occur at an older age, predominantly in women and are characterized by a high frequency of microsatellite instability and hypermethylation, whereas left CRCs occur predominantly in men and are characterized by chromosomal instability [ 40].
An epigenetic source was initially suspected to account for the high frequency of phenotypic instability.
High frequency of microsatellite instability (MSI-H) is the hallmark of tumors with a mismatch DNA repair (MMR) deficiency.
