Variations in gene copy number and disease risk

Various studies conducted in Britain and America resulted in the groundbreaking discovery that variations between humans are predominantly due to differences in the copy number of key genes that make up the human genome (Connor, 2006). In fact, current research suggests that approximately 10% of the human genome is made up of multiple gene copies, and that human variability is determined to a greater extent by variations in the gene copy number than single-base variations that occur in the genetic code (Medical News Today, 2007).

According to researchers, this discovery may be utilised to explain why some individuals are more prone to certain diseases (Connor, 2006). It is believed that additional copies of genes may lead to an overproduction of the gene’s protein which may affect traits such as cancer risk (Medical News Today, 2007). In fact, scientists at the University of Washington and Nimblegen Systems Inc. have successfully developed a technique for identifying disease risk based on the method of identifying variations in the number of copies of particular genes (Medical News Today, 2007).

It is becoming increasingly apparent that many diseases and characteristic appear to be influenced by the number of copies of certain genes (Connor, 2006). For instance, Parkinson’s disease is associated with variations in the copy number of particular genes (Connor, 2006). Furthermore, direct relationships have been observed with disease severity and the number of copies of certain genes, as observed in a study which identified a relationship between the number of SMN2 gene copies and the severity of spinal muscular atrophy in children (Arkblad, Tulinius, Kroksmark, Henricsson, & Darin, 2009). Ultimately, greater research on variations in gene copy number will result in advancements in the understanding, medical treatment, and diagnostic tests for diseases such as cancer (Connor, 2006).

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References
Arkblad, E., Tulinius, M., Kroksmark, A. K., Henricsson, M., & Darin, N. (2009). A population-based study of genotypic and phenotypic variability in children with spinal muscular atrophy. Acta Paediatrica, 98, 865-872.
Connor, S. (2006). Genetic breakthrough that reveals the differences between humans. Retrieved May 26, 2009, from http://www.independent.co.uk/news/science/genetic-breakthrough-that-reveals-the-differences-between-humans-425432.html
Medical News Today. (2007). Effects assessment of multiple copies of genes on disease risk. Retrieved May 26, 2009, from http://www.medicalnewstoday.com/articles/61987.php
Photo: http://www.latimes.com/media/photo/2008-04/37760560.jpg

Discovery Of Shared Genetic Link Between The Dental Disease Periodontitis And Heart Attack

A recent discovery of a gene has confirmed the link between Coronary heart disease and a dental disease known as periodontitis. For a long time it was believed that the two diseases were linked in some form but a genetic relationship between the two conditions has now been discovered.

The researchers discovered a genetic variant situated on chromosome 9 which was shared between the two diseases. a genetic locus on chromosome 9p21.3 that had previously been identified to be associated with myocardial infarction, in a group of 151 patients suffering from the most aggressive, early-onset forms of periodontitis and a group of 1097 CHD patients who had already had a heart attack were studied. The genetic variation associated with the clinical pictures of both diseases was identical according to the results. The scientists went on to verify the association in further groups of 1100 CHD patients and 180 periodontitis patients.They found that the genetic risk variant is located in a genetic region that codes for an antisense DNA called ANRIL and it is identical for both diseases.

Both CHD and periodontitis are propagated by the same risk factors, most importantly smoking, diabetes and obesity, there is also a gender relationship, with men possibly more liable to these diseases than women. Researchers have also shown similarities in the bacteria found in the oral cavity and in coronary plaques, and both diseases are characterised by an imbalanced immune reaction and chronic inflammation.

This discovery is significant as it can act as an alarm, if evidence of one of the diseases is showing then tests can be done to investigate susceptibility to the other disease and take appropriate preventative action.

http://www.medicalnewstoday.com/articles/151392.php
Source:
Mary Rice
European Society of Human Genetics
Article Date: 26 May 2009 - 4:00 PDT

By: Sebastian Egan 42041405

MicroRNA Protects Beta Cells

27th May 2009.

It has been recently discovered that short, noncoding RNAs are able to used to regulate important processes in the human body. For example, miRNA-375, which is present in the pancreas. Without this molecule, the beta cells in the pancreas degenerate, resulting in Diabetes.

MicroRNA was only discovered 10 years ago and research into the subject has revealed many new biological mechanisms. These RNA sequences can regulate as many as 100 genes at a time. They are found in specific cells and tissues - this fact has caused various pharmaceutical industries to conduct research using these RNA strands in the treatment of metabolic diseases and cancer.

miRNA-375 is highly concentrated in the beta cells of the pancreas. Beta cells play an important role in the regulation and control of glucose levels in the blood, as they produce the hormone insulin. Without insulin, the blood glucose levels rise and, if left untreated, the person becomes severely unwell. Without miRNA-375, the beta cells cannot grow and divide and therefore die. This leads to an overall decrease in the number of beta cells, which reduces or even completely stops the production of insulin, leading to Diabetes.

Because of their ability to regulate genes, if it were possible to influence the action of microRNA it could be possible to manipulate cells and organs to modify the development of certain conditions and diseases. The short RNA strands can be inactivated in a specific way, by a product called an Antagomir. These antagomirs can be produced synthetically and bind perfectly to the corresponding microRNA, destroying them in an efficient manner.

It is expected that this new information and the related scientific methods will be used to prevent or treat many types of medical conditions and diseases in the future.

link: http://www.sciencedaily.com/releases/2009/04/090425203534.htm

Gene Discovery Sheds Light on Childhood Cancer

Pleuropulmonary blastoma (PPB) is a rare and aggressive form of childhood lung cancer, affecting only 50 to 60 children globally a year. If identified early, it has a 90 percent cure rate however; doctors rarely expect to find lung cancer in newborns or young children. If not treated correctly, children diagnosed with PPB only have a 40 percent chance of survival.

Researchers have found that children diagnosed with PPB are born with a mutation in DICER1, a master controller gene that helps regulate other genes. In addition to this, children have normal looking cells in their lungs that appear to cause neighbouring cells to turn cancerous.

About 40 percent of cases of PPB are found in children whose families have a history of some kind of cancer, suggesting an inherited genetic cause. Researchers were surprised to discover the mutation in DICER1, which is named for its function of chopping up large molecules into smaller molecules called microRNAs that help regulate other genes.

The children with the DICER1 mutations had the defect in every cell of their body. The fact that the cell induces cancer in neighbouring cells has never been seen by scientists before. The next step for researchers is to attempt to develop a test for the DICER1 mutation that can be used to identify whether children born to high-risk families carry it and are at high risk themselves.

Researchers say that the discovery of this unexpected genetic mutation represents a whole new mechanism for the development of cancer. They also believe that the finding may shed light on adult cancers.

Published by 4209763
27^th May 2009

Reference:

Fox, Maggie (2009). Gene discovery sheds light on childhood cancer. Reuters.