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Thursday, August 11, 2011

Scientists find genes linked to migraines

Posted: 14 June 2011

PARIS - Scientists have uncovered a trio of genes tied to migraine headaches, including one in which the link is exclusive to women, according to a study published on Sunday.

Migraines are acutely debilitating headaches - sometimes with an "aura", in which patients have the impression of seeing through frosted glass - that strike up to 20 percent of the population.

Scientists describe the condition, which is three to four times more common in women, as a brain disorder in which neurons, or brain cells, respond abnormally to stimuli.

The precise cause is unknown, but inheritance is thought to play a significant role.

To assess the genetic component, Markus Schuerks of Brigham and Women's Hospital in Boston coordinated an international sweep of genomes in 23,230 women, 5,122 of whom suffered from migraines.

So-called genome-wide association studies compare differences between individuals across the approximately three billion pairs of basic molecular building blocks found in the human genetic code.

The study, published on Sunday in the British journal Nature Genetics, is the largest to date of its kind. It found variations in three genes that showed up more frequently in migraine patients.

Two of them, known as PRDM16 and TRPM8, were specific to migraines, as opposed to other kinds of headaches.

TRPM8, in addition, was linked to migraines only in women. Earlier studies have shown that the same gene contains the genetic "blueprint" for a pain sensor, in both men and women.

The third suspect gene, LRP1, is involved in sensing the external world and in chemical pathways inside the brain.

"The brain of a person with migraine responds differently to certain stimuli, their nerve cells 'talk' differently to each other," explained Shuerks in an email.

"Many neurotransmitters are involved in this cross-talk and some seem to have a special role in migraines. LRP1 interacts with some of these neurotransmitter pathways and may thus modulate nerve responses that promote or suppress migraine attacks."

None of the genetic variants appeared to be connected specifically to migraines with or without auras.

The findings, published in Nature Genetics, were replicated in two smaller population-based studies, one in the Netherlands and the other in Germany, and in a clinical group followed by the International Headache Genetics Consortium.

"Inheritance of any of the genetic variants alters migraine risk by about 10 to 15 percent," said Schuerks.

The influence of these genes is probably not large enough to be immediately used as a diagnostic tool. But the result "is an advancement of the understanding of migraine biology," he said.

- AFP/al

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Taken from ChannelNewsAsia.com; source article is below:
Scientists find genes linked to migraines

Thursday, October 15, 2009

Monkeys can now see the world in full colour

Image via Wikipedia

PARIS - Two monkeys were cured of colour blindness, thanks to gene therapy that one day may open the way to treating eye disorders in humans, scientists said yesterday.

The ground-breaking technique used a cold virus as a "Trojan horse" to infect cone-shaped cells in the retina, stealthily delivering a gene that provides a pigment which is sensitive to red.

About 20 weeks after the treatment, the two primates began to acquire full colour vision, according to the paper, published by the British journal, Nature.

It thus gives the lie to the belief that congenital vision defects become "hard-wired" through neural connections soon after birth, and cannot be corrected.

Colour vision in the two adult squirrel monkeys has remained stable more than two years after treatment, the paper says.

Red-green colour blindness affects between 5 and 8 per cent of men, and around 1 per cent of women. AFP

From TODAY, World – Thursday, 17-Sep-2009

Wednesday, September 23, 2009

Monkeys hold key to diseases

Image via Wikipedia

GENETIC BREAKTHROUGH

Twin baby monkeys, Mito (left) and Tracker, aged six days. AFP

Four baby monkeys created in a laboratory in the United States could hold the key to the eradication of a class of incurable genetic diseases, scientists revealed on Wednesday.

In an experiment that brings the creation of babies with three biological parents a step closer, Spindler, Spindly and twins Mito and Tracker were born through in-vitro fertilisation (IVF) using a technique that should make it possible to prevent women who carry genetic disorders of the mitochondria from passing them on to their children.

Defects in mitochondria - tiny structures known as the power houses or batteries of a cell because they convert food into energy for the cell - affect about one in 5,000 births and can cause about 50 known diseases, such as fatal liver failure, stroke-like episodes, blindness, muscular dystrophy, diabetes and deafness.

Mitochondrial DNA also plays a role in neurodegenerative diseases such as Alzheimer's, Parkinson's and Huntington's.

The team of scientists from the Oregon National Primate Research Centre swapped the mitochondrial DNA (mDNA) from the macaque monkey mother's egg for the mDNA of a donor egg.

The reconstructed eggs were then fertilised with the father's sperm and the healthy offspring were born.

Tests showed that no mDNA from the mother's egg had been transferred to the donor egg.

This the first time that primates have been genetically modified in this way.

The fact that healthy offspring have been produced paves the way for the use of the techniques in humans.

But the research, published in the journal Nature on Wednesday, will reignite the ethical debate over genetic engineering and so-called "designer babies".

Babies born using the new technique would inherit most of their genetic material from their mother and father, but a tiny amount - mitochondrial DNA accounts for less than 1 per cent of all the DNA in a human body - would come from the donor of the mDNA. This genetic material would then be passed on to future generations.

Mitochondria, which are strewn throughout the cell body, contain their own DNA separate from that in the nucleus of cells.

Like nuclear DNA, mDNA harbours genes that can mutate and cause disease.

However, mDNA can only be passed on to offspring via mothers' eggs. It is not transmitted by sperm.

Dr Marita Pohlschmidt, director of research at the Muscular Dystrophy Campaign, said: "We welcome these new advances and believe affected families should be offered the choice of having a healthy child." THE GUARDIAN

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From TODAY, World – Friday, 28-Aug-2009

Wednesday, May 27, 2009

World first: Japanese scientists create transgenic monkeys

AFP - Thursday, May 28

A marmoset at a zoo. In a controversial achievement, Japanese scientists announced on Wednesday they had created the world's first transgenic primates, breeding monkeys with a gene that made the animals' skin glow a fluorescent green.

PARIS (AFP) - - In a controversial achievement, Japanese scientists announced on Wednesday they had created the world's first transgenic primates, breeding monkeys with a gene that made the animals' skin glow a fluorescent green.

The exploit opens up exciting prospects for medical researchers, they said.

It could eventually lead to lab monkeys that replicate some of humanity's most devastating diseases, providing a new model for exploring how these disorders are caused and how they may be cured.

"Great advances in pre-clinical research can be expected using these models," the team said.

But other voices warned of a potential ethics storm, brewed by fears that technology used on our closest animal relatives could be turned to create genetically-engineered humans.

In a study published in the British journal Nature, a team led by Erika Sasaki of the Central Institute for Experimental Animals at Keio University reported on experiments on common marmosets (Callithrix jacchus), a small monkey native to Brazil.

They introduced a foreign gene, tucked inside a virus, into marmoset embryos that were then nurtured in a bath of sucrose.

The gene codes for green fluorescent protein (GFP), a substance that was originally isolated from a jellyfish and is now commonly used as a biotech marker. An animal tagged with GFP glows green when exposed to ultraviolet light, proving that a key gene sequence has been switched on.

The transgenic embryos were then implanted in the uterus of seven surrogate mother marmosets.

Three of recipients miscarried. The other four gave birth to five offspring, all of which carried the GFP gene.

In two of these five, the GFP gene had been incorporated into the reproductive cells. A second generation of marmosets was then derived from one of the two.

The work is important, because medical researchers have hankered for an animal model that is closer to the human anatomy than rodents.

Mice and rats, genetically engineered to have the symptoms of certain human diseases, are the mainstay of pre-clinical lab work, in which scientists test their theories before trying out any outcome on human volunteers.

But many disorders, especially neurological diseases such as Alzheimer's and Parkinson's, are so complex that they cannot be reproduced meaningfully in rodents because their biology is different.

Hopes for a non-human primate model have until now been dashed by the failure to insert a gene into a monkey's sperm and eggs -- the "germline" that ensures that the inserted DNA is passed on to future generations rather than lost.

The first genetically-modified monkey was born in 2000. Known as ANDi (the initials of "Inserted DNA," spelt backwards), the rhesus carried the GFP gene but not in its reproductive cells.

The latest exploit thus opens up hopes of eventually breeding colonies of transgenic primates with inherited traits that closely replicate human disease.

"This is the first case ever established in the world that an introduced gene was successfully inherited (by) the next generation in primates," the researchers said in a press release.

Future plans include creating transgenic marmosets that replicate human diseases such as Parkinson's and amyotrophic lateral sclerosis.

In a commentary also published by Nature, Gerald Schatten and Shoukhrat Mitalipov, primate research specialists in the US, praised the achievement as "undoubtedly a milestone" but sounded caution.

They said marmosets were not as useful as baboons or rhesus monkeys in replicating some diseases, notably HIV and tuberculosis.

Another question was the random insertion of a foreign gene in the monkey's genetic code. This may have caused some of the miscarriages and, if previous research is a guide, could unleash cancer.

Scientists also have to address legitimate public concern about animal welfare and the need for "realistic policies" to prevent genetically-engineered babies, they warned.

"There are many unanswered questions," Helen Wallace, of GeneWatch UK, a British NGO that monitors the ethics of gene research, told AFP.

"It's a big step from making a fluorescent green marmoset to making a marmoset that replicates a human disease, it's a much more complicated thing to do.

"There's also a very important ethical debate, firstly about the animals themselves and secondly about what this might lead to in the future, whether it might be ethically justified to genetically engineer humans."

From Yahoo! News; see the source article here.