The Genetics behind Eye Colour Discovered

A recent study of 4,000 people has found that the genetics behind human eye colour is in fact controlled by many genes.

The common preconception is that each child inherits two copies of each gene, one from each parent. It has been thought that ‘brown’ was the dominant trait while ‘blue’ was the recessive trait of the eye colour gene. For a ‘recessive trait’, two copies of the gene that encodes for that trait must be present, one from both parents. However, the study has found that several genes instead of a single gene contribute to the eye colour of any individual.

A very small difference in one gene, OCA2 can account for around 74 per cent of the total variations in eye colour. The OCA2 gene produces a protein that helps give hair, skin and eyes their colour. Furthermore, small differences in another part of the OCA2 gene have also been linked to green and hazel eyes. Although it is yet to be discovered, it is believed that at least two other genes underlie these colours.

Part of the complexity is that eye colour is a continuum and not merely a trait with a few separate varieties. For this reason, it is possible for a person with not completely blue eyes and has a brown pupil ring to produce a brown-eyed child.

http://www.cosmosmagazine.com/node/1062

Rebekah Lim

The Genetics behind Eye Colour Discovered

A recent study of 4,000 people has found that the genetics behind human eye colour is in fact controlled by many genes.

The common preconception is that each child inherits two copies of each gene, one from each parent. It has been thought that ‘brown’ was the dominant trait while ‘blue’ was the recessive trait of the eye colour gene. For a ‘recessive trait’, two copies of the gene that encodes for that trait must be present, one from both parents. However, the study has found that several genes instead of a single gene contribute to the eye colour of any individual.

A very small difference in one gene, OCA2 can account for around 74 per cent of the total variations in eye colour. The OCA2 gene produces a protein that helps give hair, skin and eyes their colour. Furthermore, small differences in another part of the OCA2 gene have also been linked to green and hazel eyes. Although it is yet to be discovered, it is believed that at least two other genes underlie these colours.

Part of the complexity is that eye colour is a continuum and not merely a trait with a few separate varieties. For this reason, it is possible for a person with not completely blue eyes and has a brown pupil ring to produce a brown-eyed child.

http://www.cosmosmagazine.com/node/1062

Rebekah Lim

Child Abuse and Adult Suicide: a Similarity?

The DNA we inherit from our parents is located in all of our cells and remains unchanged during our lives; changes in gene functions can have detrimental effects on behaviour. Epigenetics is a field within biology that focuses on these functional changes, that don’t require changes in actual gene sequence. Epigeneticists from The Department of Pharmacology and Therapeutics at McGill University, Quebec, recently published their results on the affects of environmental factors on the genes in brains of suicide victims. Leader of the research project Moshe Syzfa claims “the study highlighted real differences between the brains of men who committed suicide and the brains of men who did not”.

The study found that although the genetic sequence was the same, the epigenetic markings differed. There appeared to be a chemical coating on the genes of the 13 suicide victims studied, all of which had been victims of child abuse earlier in their lives. It is currently understood that during pregnancy a chemical coating called ‘DNA Methylation’ creates marks in our DNA that instruct it to express certain genes. These marks are relatively sensitive and can easily be affected by our environment in early childhood (see DNA Methylation for more details); hence "it's possible the changes in epigenetic markers were caused by the exposure to childhood abuse” (Syzfa, 2008) and are not inherited.

In completing the study, the researcher’s analysed a set of genes that code for ribosomal RNA (rRNA) as the creation of proteins can be regulated epigenetically. The translation of certain proteins is essential for many motor processes such as learning, memory and decision-making, particularly in early childhood. If these proteins are not coded for or if mutations occur at this stage in one’s lifecycle, the effects could cause a lack of neural connections and thus, individual differences in the risk of suicide.

With epigenetic studies such as this identifying the causing agent of suicidal issues, the focus is now turning to whether scientists can detect changes in blood DNA and therefore develop interventions to erase these differences soon after diagnosis.

For full article see: http://www.medicalnewstoday.com/articles/106639.php

For more information: http://www.livescience.com/health/080506-suicide-epigenetics.html

http://www.scienceagogo.com/news/20080406232345data_trunc_sys.shtml

Depressed and Angry Uni Students?

When you graduate university you have a degree, maybe a job and a seemingly bright future ahead of you but is this really the case. In a recent study by the University of Alberta on 600 recent post-graduates it was found that students had a high level of depression and anger after finishing university. The seven year long study found that events such as leaving home and becoming a parent increased levels of stress and anger. Also they found that younger participants who lived by themselves had greater levels of depression while older participants were more depressed if they lived with their parents. At the beginning of the study women were more depressed than men, the increased levels of anger after having a child were not as surprising. Although parenthood is seen as a rewarding experience the birth of a child can put a strain on a relationship and increase stress levels between couples, even more so in single parents. The bright side is that almost all participants had decreased depression and anger at the end of the study. So if you’re finishing university be ready for a few tough years but it will get easier.

Sources: http://www.ualberta.ca/
Depression and anger can plague recent university graduates: Study

Gene discovered that causes a unique facial abnormality

In a collaborative effort researchers from the Boston University of Medicine have discovered the gene for BOFS. The disorder is caused by a deletion within the TFAP2A gene (Activating Enhancer-Binding Protein).

Branchio-Oculo-Facial Syndrome also known as BOFS is a rare facial genetic disorder that is inherited as an autosomal dominant trait. This genetic disorder is congenital and over the past 4 years since 2004 only 50 cases have been medically recorded. The symptoms of people who have BOFS include: low birth weight, retarded growth and mental retardation. Patients with BOFS are characterised by facial abnormalities including the presence of a pseudocleft of the upper lip, a malformed nose, blockage of tear ducts, malformed ears, lumps on the neck and collar bone and skin lesions behind the ears.

It was discovered using modern molecular microray technologies. The university examined an affected mother and son and found that they both had deletions present in their chromosome 6. After their genes were structured according to the patient’s location it was found that there were missense mutations clustered in the region of DNA-binding domain on the TFAP2A gene.

This discovery will lead to more accurate testing and even prenatal diagnosis. It may also be able to play a role in identifying genes and disorders with more common forms of the occurrence of a cleft lip and palate.

To find out more visit:

http://www.healthjockey.com/2008/04/30/gene-for-branchio-oculo-facial-syndrome-discovered-by-researchers/

http://www.bchealthguide.org/kbase/nord/nord714.htm

By Odette Pletzer 41776960

Gene discoveries could crack bone disease

Gene mutations linked with osteoporosis have been identified independently by teams in the UK and Iceland.

Earlier unsubstantiated reports have linked genes to the bone-weakening disease but the new studies are the first to conclusively identify the mutations.

Both teams found the mutations by screening for hundreds of thousands of random mutations - called single nucleotide polymorphisms or SNPs - in DNA samples from thousands of women, both with and without osteoporosis.

The two mutations reported by the British team are so common they might be worth screening for. "They're both present in more than one in five white people, suggesting a potential role in screening," says Tim Spector of King's College London, and principal investigator in the study. "In theory we could start screening right away."

Having both mutations raises the risk of osteoporosis by up to 50%, and of bone fractures by up to 30%.

Spector said that screening women over 60 could help identify those needing treatment to avoid fractures. Screening teenagers could identify girls who could avoid future disease through lifestyle changes, such as drinking more milk and exercising more.

Osteoporosis genes

One mutation is on the LRP5 gene which makes lipoprotein-receptor-related protein, a molecule on the surface of osteoclast cells that helps control whether or not they mature into bone cells. Carriers of the mutation were 30% more likely than non-carriers to suffer osteoporosis or related fractures.

The second mutation was on the TNFRSF11B gene which makes osteoprotegerin, a signaling molecule that blocks bone resorption. Carriers are more likely to have lower bone mineral density, and are 20% more likely to suffer fractures.

Being linked with bone formation and resorption, the mutations also provide new targets for drug development, says Spector's team.

Knitting results together

The Icelandic team, led by Kari Stefansson of DeCode Genetics in Reykjavik, identified five mutations linked with osteoporosis, including the one in the osteoprotegerin gene found by the British team. But the associations they found were weaker in the population of women they screened.

"Although these variants alone are not clinically useful in the prediction of risk to the individual person, they provide insight into the biochemical pathways underlying osteoporosis," the team report.

Spector said the Icelandic group also identified the same LRP5 mutation as the British group, but the association wasn't strong enough for it to be included among the five most significant mutations. "Effectively, they replicated our findings," he says.

Significantly, the five reported by DeCode included one linked with a major experiment drug currently undergoing clinical trials. The mutation is in the gene for RANKL (receptor activator of nuclear factor-κB ligand), a molecule that triggers resorption of bone.

Amgen, a biotechnology company in Thousand Oaks, California, is in the final stages of testing denosumab, a monoclonal antibody designed to block bone resorption by neutralizing RANKL.

Further Reading:
The Lancet, DOI: 10.1016/20140-6736(08)60600-5, The New England Journal of Medicine, DOI: 10.1056/NEJMoa0801197

Student no: 41791806

Joon Park

Gene Sequence That Can Make Half Of Us Fatter Is Discovered

Scientists from the Imperial College in London has discovered gene sequence that is associated with expansion in waist circumference and weight gains and the tendency to develop type II obesity. This gene sequence is significantly more common in individuals with Indian Asian background more than individuals with European ancestors. The discovery of this genetic sequence provides a possible explanation of high levels of obesity and insulin resistance in the Indian population.
This gene sequence is closely linked to a gene called MC4R that is responsible for regulating the body's energy levels which in turn, controls our food consumption and energy output. The discovery of this particular gene sequence could help scientists and dietitians to transform the management of obesity and help to identify individuals whose genetic inheritance makes them most susceptible to obesity and other related problems like cardiovascular diseases in the future. This finding is very significant as 25% of the world's population has this genetic sequence and are expected to contribute 40% of global cardiovascular diseases. As genetic inheritance cannot be changed within the population, preventative measures such as exercise and new drug targets can be used to reduce the effects of the obesity.

Your Genome at the click of a button

While we strive to learn more about the world around us, we neglect the fact that we know very little about ourselves and what tomorrow has on offer for us - until now, that is! Now there are companies that offer people the opportunity to delve into their genome and see their own destiny. Silicon Valley startup 23andME has begun to offer personal genotyping service. For a mere $1000 and vial of spit, 23andME will run a sample of your DNA and identify "nearly 600,000 data points on your genome". They will, then, load your information up onto their website and you are free to investigate your genome at your own leisure!

23andMe isn't the only company mapping your genome - deCODE Genetics, a biopharmaceutical business in Iceland, offers a similar service called deCODEme. However, 23andMe may has a huge advantage over all its other competitors because it has the might of Google behind it. Google's investment in 23andMe suggests that this company wishes to extend its services beyond individual gene maps. Think about it, as its online store of genetic information develops, the company is assured to end up with a database of invaluable information for pharmaceutical companies and medical researchers.

This database could reveal hidden connections between genes and diseases, and 23andME has recognised this and seems to want to utilize it. In a statement, 23andME states that it wishes to grant external groups access to its database and allow them to search "without knowing the identities of the individuals involved" for links between genetic variations and health conditions. Gene mapping bound to turn into a lucrative business and given that people can be easily tracked via cookies on the internet, it may not be long before we see genetically targeted advertising.

For futher information:
https://www.23andme.com/
http://www.reuters.com/article/internetNews/idUSN1948129620071119
http://www.news.com/Google-invests-3.9-million-in-biotech-start-up/2100-1014_3-6185860.html

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