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Cancer in IBD
Published in Peter Sagar, Andrew G. Hill, Charles H. Knowles, Stefan Post, Willem A. Bemelman, Patricia L. Roberts, Susan Galandiuk, John R.T. Monson, Michael R.B. Keighley, Norman S. Williams, Keighley & Williams’ Surgery of the Anus, Rectum and Colon, 2019
Second, different molecular pathways are described to contribute to colitis-associated carcinoma.18 The chromosomal instability (CIN) pathway seems to attribute to cancer formation. Within this pathway, loss of homozygosity of p-53 due to mutations seems to occur earlier than APC mutations, and this is thought to be the key-initiating event, occurring in 50% to 85% of colitis-associated colorectal cancer.19 Next to the CIN pathway, an important pathway for the development of colorectal cancer is the macrosatellite instability (MSI) pathway, the typical pathway in Lynch syndrome. The role of the MSI-pathway in colitis-associated carcinoma remains unclear but has been described in these cancers.20 Finally, the role of the methylation pathway and serrated neoplasia pathway are both subjects of study.
The gene mutations and subtelomeric DNA methylation in immunodeficiency, centromeric instability and facial anomalies syndrome
Published in Autoimmunity, 2019
Haochang Hu, Chujia Chen, Shanping Shi, Bin Li, Shiwei Duan
The human subtelomeric region adjacent to the telomere is mainly composed of repeat sequences. Although the subtelomeres in human sperm and oocytes are almost not methylated, these regions are de novo methylated by DNMT3B during early embryonic development [15]. An abnormal telomere phenotype occurs when DNMT3B is mutated, indicating that subtelomeric methylation plays a key role in human telomere maintenance [16]. A growing body of studies has shown that subtelomeric DNA methylation plays a key role in many diseases [17]. During the development of liver cancer, the telomere length is prolonged, accompanied by hypomethylation of chromosome 7q subtelomeres and hypermethylation of chromosome 21q subtelomeres [18]. Patients with facioscapulohumeral muscular dystrophy (FSHD) 1 lost the D4Z4 macrosatellite repeat unit with high methylation and epigenetic silencing in the subtelomere region of the long arm in chromosome 4q [19,20].