Human Pregnancies can Vary in Length Naturally by as Much as 5 Weeks

by Thilaka Ravi on? August 07, 2013 at 9:07 PM Women Health News Research published online today in Europe's leading reproductive medicine journal Human Reproduction says the length of a human pregnancy can vary naturally by as much as five weeks.
Normally, women are given a date for the likely delivery of their baby that is calculated as 280 days after the onset of their last menstrual period. Yet only four percent of women deliver at 280 days and only 70% deliver within 10 days of their estimated due date, even when the date is calculated with the help of ultrasound.

Now, for the first time, researchers in the USA have been able to pinpoint the precise point at which a woman ovulates and a fertilised embryo implants in the womb during a naturally conceived pregnancy, and follow the pregnancy through to delivery. Using this information, they have been able to calculate the length of 125 pregnancies.

"We found that the average time from ovulation to birth was 268 days - 38 weeks and two days," said Dr Anne Marie Jukic, a postdoctoral fellow in the Epidemiology Branch at the National Institute of Environmental Health Sciences (Durham, USA), part of the National Institutes for Health. "However, even after we had excluded six pre-term births, we found that the length of the pregnancies varied by as much as 37 days.

"We were a bit surprised by this finding. We know that length of gestation varies among women, but some part of that variation has always been attributed to errors in the assignment of gestational age. Our measure of length of gestation does not include these sources of error, and yet there is still five weeks of variability. It's fascinating."

The possibility that the length of pregnancies can vary naturally has been little researched, as it is impossible to tell the difference between errors in calculations and natural variability without being able to measure correctly the gestational age of a developing foetus. Previous studies conducted as long ago as the 1970s and 1980s had used the slight rise in a woman's body temperature at waking as a way of detecting when ovulation occurred. This is an inexact measurement and cannot be used to detect when the embryo actually implants in the womb.

In the current study, the researchers took information from daily urine samples collected by women taking part in an earlier study, the North Carolina Early Pregnancy Study, which took place between 1982-1985 and followed 130 singleton pregnancies from unassisted conception through to birth. The women had discontinued contraception in order to become pregnant; they were healthy, with no known fertility problems and they were also less likely to smoke or be obese. The women completed daily diaries and collected daily first-morning urine samples for six months or until the end of the eighth week if they became pregnant.

The urine samples were analysed for three hormones connected with the onset of pregnancy: hCG (human chorionic gonadotropin), estrone-3-glucoronide and pregnanediol-3-glucoronide. The day of ovulation was identified by the drop in the ratio between the hormones oestrogen and progesterone. Embryo implantation was identified as the first day of a sustained rise in levels of hCG. "Since the embryo secretes hCG, and mothers generally have little to no hCG in their urine when they are not pregnant, we used the earliest increase in hCG to indicate implantation," explained Dr Jukic.

In 2010, the researchers contacted the women for the current study to obtain information about their labour and whether induction or Caesarean section had been required. Full information was available on 125 pregnancies after excluding those that had been affected by exposure to diethylstilbestrol - an endocrine disrupter that is known to shorten pregnancies.

In addition to the variation in the length of gestation, the study found that embryos that took longer to implant, also took longer from implantation to delivery, and that pregnancies that showed a late progesterone rise were significantly shorter by an average of 12 days than pregnancies with an early rise.

Dr Jukic said: "I am intrigued by the observation that events that occur very early in pregnancy, weeks before a woman even knows she is pregnant, are related to the timing of birth, which occurs months later. I think this suggests that events in early pregnancy may provide a novel pathway for investigating birth outcomes."

Other factors that appeared to influence pregnancy duration included: older women delivered later on average, with each year of age adding roughly one day to their pregnancy; women who had themselves been heavier at birth had longer gestations, with each 100g in the mother's own birthweight corresponding roughly to a one-day longer pregnancy; and if a woman had longer pregnancies previously or subsequently to the pregnancy being investigated in the study, then the study pregnancy was likely to be longer, with a one-week increase in the average length corresponding to about a 2.5-day longer pregnancy in the study. "This last finding suggests that individual women tend to be consistent about when they deliver," said Dr Jukic.

In their paper, the authors conclude: "The length of human gestation varies considerably among healthy pregnancies, even when ovulation is accurately measured. This variability is greater than suggested by the clinical assignment of a single 'due date'. The duration of previous pregnancies may provide a useful measure of a woman's 'natural' length of pregnancy and may help in predicting an individual woman's due date. We also found that events in the first two weeks after conception were strongly predictive of the total length of pregnancy, suggesting that the trajectory for the timing of delivery may be set in early pregnancy."

They warn that it is too early to make clinical recommendations based on their study and that further research needs to be carried out.

Dr Jukic concluded: "I think the best that can be said is that natural variability may be greater than we have previously thought, and if that is true, clinicians may want to keep that in mind when trying to decide whether to intervene on a pregnancy."

Source-Eurekalert

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Genetic 'Switches' Do Play Big Role in Human Evolution: Study

The study provides evidence for a 40-year-old hypothesis that regulation of genes must play an important role in evolution since there is little difference between humans and chimps in the proteins produced by genes.

Indeed, human and chimpanzee proteins are more than 99 percent identical.

The researchers showed that the number of evolutionary adaptations to the part of the machinery that regulates genes, called transcription factor binding sites, might be roughly equal to adaptations to the genes themselves.

"This is the most comprehensive and most direct analysis to date of the evolution of gene regulatory sequences in humans," said senior author Adam Siepel, Cornell associate professor of biological statistics and computational biology.

"It's taken these 40 years to get a clear picture of what's going on in these sequences because we haven't had the data until very recently," said Leonardo Arbiza, a postdoctoral researcher in Siepel's lab and the paper's lead author.

Less than 2 percent of the human genome - the complete set of genetic material - contains genes that code for proteins. In cells, these proteins are instrumental in biological pathways that affect an organism's health, appearance and behavior.

Much less is known about the remaining 98 percent of the genome; however, in the 1960s, scientists recognized that some of the non-protein coding DNA regulates when and where genes are turned on and off, and how much protein they produce. The regulatory machinery works when proteins called transcription factors bind to specific short sequences of DNA that flank the gene, called transcription factor binding sites, and by doing so, switch genes on and off.

Among the findings, the study reports that when compared with protein coding genes, binding site DNA shows close to three times as many "weakly deleterious mutations," that is, mutations that may weaken or make an individual more susceptible to disease, but are generally not severe. Weakly deleterious mutations exist in low frequencies in a population and are eventually weeded out over time. These mutations are responsible for many inherited human diseases.

While genes generally tend to resist change, a mutation occasionally leads to a favorable trait and increases across a population; this is called positive selection. By contrast, "transcription factor binding sites show considerable amounts of positive selection," said Arbiza, with evidence for adaptation in binding sites that regulate genes controlling blood cells, brain function and immunity, among others.

"The overall picture shows more evolutionary flexibility in the binding sites than in protein coding genes. This has important implications for how we think about human evolution and disease," said Siepel.

The study was published June 9 in Nature Genetics.

Source-ANI

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Scientists Map Ultra-high 3-D Resolution of Human Brain

It shows the human brain at a spatial resolution of 20 microns, smaller than the size of one fine strand of hair-exceeding that of existing reference brains presently in the public domain.

The new tool is made freely available to the broader scientific community to advance the field of neuroscience.

Researchers from Germany and Canada collaborated on the ultra-high resolution brain model.

The sophisticated modern image processing methods reveal an unprecedented look at the very fine details of the human brain's microstructure, or cellular level.

The anatomical tool will allow for three-dimensional cytoarchitectonic mapping of the human brain and serve as an atlas for small cellular circuit data, or single layers or sublayers of the cerebral cortex, explained the researchers.

Until recently, reference brains did not probe further than the macroscopic, or visible, components of the brain.

Now, the BigBrain provides a resolution much finer than the typical 1 mm resolution from MRI studies.

The findings are published in the journal Science, which is published by AAAS, the international non-profit science society.

Source-ANI

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'Human Liver' from Stem Cells Created

by Sheela Philomena on? July 04, 2013 at 11:43 AM Genetics & Stem Cells News Scientists have created human liver tissue from stem cells. Creating lab-grown tissue to replenish organs damaged by accident or disease is a Holy Grail for the pioneering field of research into the premature cells known as stem cells.
Now Takanori Takebe of the Yokohama City University Graduate School of Medicine and a team report in the journal Nature that they grew tissue "resembling the (human) adult liver" in a lab mouse.

They first created induced pluripotent stem (iPS) cells which they mixed with other cell types and coaxed into "liver buds" -- the precursor clusters that develop into a liver.

The buds, each about five millimetres (0.2 inches) big, were then transplanted onto a mouse brain, where they were observed transforming into a "functional human liver" complete with blood vessels, the scientists wrote.

"To our knowledge, this is the first report demonstrating the generation of a functional human organ from pluripotent stem cells," said the report.

The technique has yet to be tested in humans, but serves as an important proof of concept, it added.

Stem cells are infant cells that can develop into any part of the body.

Until a few years ago, when iPS cells were created, the only way to obtain stem cells was to harvest them from human embryos.

This is controversial because it requires the destruction of the embryo, a process to which religious conservatives and others object.

iPS cells are easily-obtainable mature cells that are "reprogrammed" into a versatile, primitive state from where they can develop into any kind of cell in the body.

Takebe told a press conference ahead of the report's release that the man-made liver was observed through a replacement glass skull that was fitted around the mouse's brain.

The liver developed blood vessels which fused with those of the animal.

It also performed certain human-specific liver functions -- producing proteins and processing specific drugs.

"We have concluded that this liver is functioning," the scientist said. "We think this is enough for improving the survival after liver failure."

Scientists commenting on the research described it as promising.

"This science opens up the distinct possibility of being able to create mini-livers from the skin cells of a patient dying of liver failure," said Malcolm Alison, professor of stem cell biology at the Queen Mary University of London.

"Human mature liver cells transplanted on their own can fail to thrive, but if immature liver cells are first combined with their normally nurturing supportive cells, they can mature in the transplanted host and function efficiently," he said in a statement issued by the Science Media Centre.

Dusko Ilic from Kings College London said "the promise of an off-shelf-liver seems much closer than one could hope even a year ago", but the strategy has yet to be proven in humans.

"Whilst the title of the paper is 'functional human liver', these liver buds do not contain the biliary structures (which drain toxins out of the liver) or immune cells that characterise real human liver," added Stuart Forbes, professor of transplantation and regenerative medicine at the University of Edinburgh.

Chris Mason of University College London said the buds may be useful for drug testing in the lab, which is currently restricted by the limited availability of liver cells from human cadavers.

Takebe said the method may also work in organs like the pancreas, kidneys or lungs, but it would be another 10 years before trials are done in humans.

One key requirement would be to shrink the "buds" to a much smaller size so they can be injected into the bloodstream and taken up by the body internally, he said.

Source-AFP

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Thank Fish for Human Hand Gestures: Scientists

Scientists have found that the evolution of the control of speech and hand movements can be traced back to the same place in the brain, which could explain why we use hand gestures when we are speaking.

"We have traced the evolutionary origins of the behavioural coupling between speech and hand movement back to a developmental compartment in the brain of fishes," Professor Andrew Bass of Cornell University said.

"Pectoral appendages (fins and forelimbs) are mainly used for locomotion. However, pectoral appendages also function in social communication for the purposes of making sounds that we simply refer to as non-vocal sonic signals, and for gestural signalling."

Studies of early development in fishes show that neural networks in the brain controlling the more complex vocal and pectoral mechanisms of social signalling among birds and mammals have their ancestral origins in a single compartment of the hindbrain in fishes.

This begins to explain the ancestral origins of the neural basis for the close coupling between vocal and pectoral/gestural signalling that is observed among many vertebrate groups, including humans.

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High Demand for Human Breast Milk Sees Firms Offering Wet Nurses for Adults

by Kathy Jones on? July 05, 2013 at 11:24 PM General Health News The rising demand for human breast milk among the China's rich has led to some firms offering wet nurse services even for adult clients, sparking outrage among web users.
Xinxinyu, a domestic staff agency in the booming city of Shenzhen, which borders Hong Kong, provided wet nurses for newborns, the sick and other adults who pay high prices for the milk's fine nutrition, the Southern Metropolis Daily said.

"Adult (clients) can drink it directly through breastfeeding, or they can always drink it from a breast pump if they feel embarrassed," the report quoted company owner Lin Jun as saying.

Wet nurses serving adults are paid around 16,000 yuan ($2,600) a month -- more than four times the Chinese average -- and those who were "healthy and good looking" could earn even more, the report said.

Traditional beliefs in some parts of China hold that human breast milk has the best and most easily digestible nutrition for people who are ill.

But the report sparked heated debate in the media and on Chinese social media, with most users condemning the service as unethical.

"This adds to China's problem of treating women as consumer goods and the moral degradation of China's rich," said Cao Baoyin, a writer and regular commentator in various Chinese media, on his blog.

Xinxinyu has been ordered to suspend its operations and had its business licence revoked for multiple reasons including missing three years of annual checks, regulators in Shenzhen told AFP on Thursday, although the wet nurse service was not among the factors they cited.

Company officials could not be reached for comment by AFP.

There were nearly 140,000 postings on Sina Weibo, a Chinese equivalent of Twitter, on the topic by Thursday afternoon.

In an online poll, almost 90 percent of participants voted against the service, saying it "violated ethical values", a fraction over 10 percent deemed it a "normal business practice".

"People become perverts when they are too rich and tired of other forms of entertainment. This is disguised pornography," said a user with the online handle ricky_gao.

White Lotus, another weibo writer, said: "Please do not force motherhood to lose its grace and become ridiculous."

Other postings voiced cynical approval.

"It's just a business, nothing to blame it for," said A Xiao Shuai. "People are insensitive about ethics when there is money on the table."

Among the general population in China breastfeeding rates are low -- just 28 percent according to a 2012 UNICEF report -- due to time limits on maternity leave and aggressive marketing of formula.

Source-AFP

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Neuroscientist Claims Full Human Head Transplant Possible

In a paper published recently, Dr Sergio Canavero, of the Turin Advanced Neuromodulation Group in Italy, said that these advancements mean that surgeons will now theoretically be able to fuse a human spinal cord just like it happened in Mary Shelley's classic story 'Frankenstein,' the Sun reported.

The last attempt was done in 1970 when the head of a Rhesus monkey was transplanted onto another at a lab in Ohio, US, and even though the simian lived for 8 days, it was never able to move below the neck, as the 'axons' in its spinal cord could not be repaired.

However, Canavero believes that he will be able to do this thanks to chemicals called 'membrane fusogens' or sealants, some of which are already used for making medicines.

He claimed in the paper that the greatest technical obstacle to endeavor like these is reconnecting donor's and recipient's spinal cords, adding that he believes that the technology now exists for such sort of linkages.

Source-ANI

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Cancer Drug Responsiveness in Human Tumors Predicted By UNC Murine Study

UNC scientists used GEMMs to develop biomarkers for challenging molecular subtypes of human breast cancer, those for which there are fewer targets and therapies. Their work helps to further establish genetically engineered mouse models as predictors of human response to therapy.

The molecular subtypes of breast cancer that the UNC group focused on - basal-like, luminal B, and claudin-low - are the most challenging types of breast cancer because these are tumors that don't typically respond to drugs such as Herceptin or aromatase inhibitors. UNC was among the first to characterize these tumor subtypes, and this new report extends the understanding of them.

The UNC team found that GEMMs were able to accurately predict human response to a standard chemotherapy drug combination commonly used in the clinic.

Charles Perou, PhD, study senior author, says, "This is a wonderful example of how well chosen mouse models can inform a human disease state. In this case we used years of research to match the models to specific human subtypes, and then treated the animals with therapies identical to what human cancer patients are receiving. We were ultimately able to develop a biomarker of treatment response from the mouse that works in humans."

Dr. Perou is the May Goldman Shaw Professor of Molecular Oncology Research and a member of UNC Lineberger Comprehensive Cancer Center.

Their findings were published in the June 19, 2013 online issue of the journal Clinical Cancer Research.

The team developed murine-derived gene signatures that corresponded to a distinct treatment response and then tested their predictive potential using human patient data. Their research tested single agents carboplatin, paclitaxel, erlotinib and lapatinib. Although one single agent exhibited exceptional efficacy, other single agents offered more modest results.

The team identified a pair of gene expression signatures that predicted pathological complete response to neoadjuvant anthracycline (doxorubicin)/taxane (paclitaxel) therapy in human patients with breast cancer, even among the difficult to treat triple negative patient subset.

Traditional mouse model research was conducted using mice without immune systems into which human tumors or cell lines were grafted. In contrast, by manipulating genes in GEMMs scientists are able to observe how cancer develops as it does in humans, in the presence of an immune system, thus making the results more similar to human cancers.

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Human Immunity to H7N9 Flu Virus is too Low

The study used a new, high throughput method that allows blood samples to be analysed for antibodies to multiple human and animal influenza viruses at the same time and is easier to standardise than previous techniques. However, the assay is yet to be validated clinically for the H7N9 virus, and the researchers caution that the results must be interpreted with care.

Since the first case of H7N9 infection in humans was reported in February 2013, there have been 131 confirmed cases and 36 deaths, all in China apart from one case in Taiwan. All of the infections seem to have come from infected poultry and there is no evidence of sustained transmission between people. One of the first key pieces of information that officials need when considering how best to respond to the threat of a pandemic is how much, if any, immunity the human population has to this virus. This helps to predict where the virus is likely to affect first and how likely it is that the virus will spread further. Having this knowledge also helps to understand the risks of severe infection, as well as helping to target protective measures such as where to direct antiviral medication.

Researchers at the Wellcome Trust Oxford University Clinical Research Unit (OUCRU) in Vietnam tested 1723 blood samples collected in southern Vietnam for the presence of antibodies to five different bird flu viruses, including one from the H7 sub type. The presence of antibodies would be an indication of past exposure to these particular strains of flu. They used a new technique that was developed by their research collaborators at the National Institute of Public Health of The Netherlands that is faster and easier to use than previous methods.

The results reveal that although the level of antibodies to the H7 sub-type of flu virus are higher than any of the H5 sub-types tested, levels of antibodies to all five bird flu viruses are much lower than to human flu viruses. This suggests that people living in this particular area of Vietnam have had very little or no exposure to the H7 sub-type of virus, similar to other bird flu viruses. As this population of people would be expected to be among the first to be affected in the event of a pandemic, these findings have important implications for pandemic preparedness plans in this area.

Dr Maciej Boni, a Sir Henry Dale Fellow at the OUCRU and first author of the study, explains: "H7N9 is a virus that until now has only infected birds so it's not surprising that we don't find much evidence of humans having been exposed to it. It is reassuring that in Vietnam we don't see any evidence that the current outbreaks represent a tip-of-the iceberg observation of widespread H7N9 infection in people. On the other hand, the low antibody levels indicate that there is likely to be very little immunity to this virus."

Around half of the samples were taken from an urban environment, Ho Chi Minh City, and half from a rural area, the nearby Khanh Hoa province. The team found no difference in the level of immunity to bird flu viruses between these two populations, even though people living in rural areas are more likely to live in close proximity to poultry.

"It has been suggested that people who live in closer proximity to chickens and other birds will have higher levels of immunity to bird flu viruses simply because their exposure is likely to be greater. However we find no evidence for this. Our findings would suggest that both rural and urban populations should be treated the same when considering how best to respond to the threat of an outbreak," added Dr Boni.

Professor Jeremy Farrar, Director of the Wellcome Trust Major Overseas Programme in Vietnam and the Oxford University Clinical Research Unit Hospital for Tropical Diseases, explains: "This is the first study to give us information about the level of antibodies and potentially human immunity to this new bird flu virus, H7N9 in the region. But we need to interpret the findings cautiously, these assays are relatively new and we need to understand how they correspond to existing assays and how they reflect past infection and true human immunity.

"We know that antibodies are very important for immunity to other flu viruses but at this stage, we still don't know what level of antibody measured using this assay would provide protection against this novel strain. Further studies will be needed to understand the clinical relevance of these new assays, how they compare with classic techniques and what the apparent absence of antibodies to these viruses in the human population means. However these new techniques do allow for much higher throughput of samples, ease of use and once validated may allow much more rapid assessment of the spread of infection and levels of population immunity than do traditional assays."

The study, which was carried out in collaboration with scientists at the National Institute for Public Health and the Environment (RIVM) in the Netherlands, is published online this week in the Journal of Infectious Diseases.

Professor Marion Koopmans, who is Head of Virology at the RIVM and senior author of the study, said: "We developed this technique exactly to be used in the current situation: we wanted a standardised test that allowed us to rapidly compare antibodies to the new virus with those to influenza viruses that we already know are common in people. The level of immunity to a new virus is one of the important questions during any emerging disease outbreak. We need only one drop of blood, so that tests can also be run when only small sample volumes are available, for instance when testing children. For outbreak investigations, testing of animals may be needed, and we are currently working on that. To do the clinical validation studies, we need blood samples from patients (and animals) with confirmed H7N9, and we hope to be able to do that soon through collaborations with other groups working on H7N9."

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Researchers Conduct Genomic Survey of Human Skin Fungal Diversity

In the first study of human fungal skin diversity, National Institutes of Health researchers sequenced the DNA of fungi at skin sites of healthy adults to define the normal populations across the skin and to provide a framework for investigating fungal skin conditions.

Human skin surfaces are complex ecosystems for microorganisms, including fungi, bacteria and viruses, which are known collectively as the skin microbiome. Although fungal infections of the skin affect about 29 million people in the United States, fungi can be slow and hard to grow in laboratories, complicating diagnosis and treatment of even the most common fungal skin conditions, such as toenail infections.

The research team from the National Human Genome Research Institute (NHGRI) and the National Cancer Institute (NCI), both parts of NIH, extended their recent genome sequencing study of skin bacteria, using DNA sequencing techniques optimized for identifying fungi. The study appears in the May 22, 2013 early online issue of Nature.

The researchers found that a single type of fungus, belonging to the genus Malassezia, is predominant on the head and trunk. Hands, which harbor a great diversity of bacteria, are home for relatively few types of fungi. In contrast, feet, including toenails, heels and toe webs contain tremendous diversity.

"Applying DNA sequencing to a study of the skin's fungi is the natural progression in understanding microbial life that co-exists on our bodies," said NHGRI Scientific Director Daniel Kastner, M.D., Ph.D. "Along with recent genome sequencing to define bacterial diversity, this analysis of fungal diversity provides a more complete human microbiome picture."

"Fungal communities occupy complex niches, even on the human body," said Heidi Kong, M.D., co-senior author and an investigator in the dermatology branch of NCI's Center for Cancer Research. "By gaining a more complete awareness of the fungal and bacterial ecosystems, we can better address associated skin diseases, including skin conditions which can be related to cancer treatments."

The researchers collected samples at 14 body sites from 10 healthy adults. DNA sequencing of the fungi in the samples identified fragments of DNA, called phylogenetic markers, which can be counted and used to distinguish one type of fungus from another. The sequencing efforts generated more than 5 million markers, from the samples, representing more than 80 fungal types, or genera. In contrast, traditional culturing methods produced 130 colonies of fungi that represented only 18 fungal genera.

In 20 percent of the study participants, the researchers observed problems such as heel and toe web scaling or toenail changes consistent with possible fungal infections. From genome sequencing analysis, the researchers found that different individuals with heel site infections have common fungal communities at that site, while those with toenail infections display tremendously different fungal communities.

"DNA sequencing reveals the great diversity of fungi, even those that are hard to grow in culture," said Julie Segre, Ph.D., co-senior author and senior investigator, NHGRI Genetics and Molecular Biology Branch. Her expertise is the development of microbial DNA sequencing technology. "DNA sequencing enabled us to learn immeasurably more about where fungi predominate as a part of the human skin microbiome."

The researchers identified fungi from two phyla, Ascomycetes and Basidiomycetes, as part of the normal fungal census at the 14 skin sites. The most common genus Malassezia was present in 11 of 14 sites sampled on the body. The researchers found Malassezia fungus on every skin surface of healthy volunteers, whether on the back of the head, behind the ears, in nostrils and on the heels. Heels were also home to many additional fungi, including the genera Aspergillus, Cryptococcus, Rhodotorula, and Epicoccum.

"DNA sequence-based methods of identification enabled us to differentiate among species of fungi and to conclude that the diversity of fungi is highly dependent on the body site rather than the person who is sampled," said Dr. Kong. A dermatologist, Dr. Kong explained why these sites were selected for exploration: "Our study focused on areas of the skin where we commonly find skin diseases that have been associated with fungi."

The most complex site, the heel, is home to about 80 genus-level types of fungi. The researchers found about 60 types in toenail swab samples and 40 types in samples from the webs of the toes. Sites with moderate fungal diversity are inside the bend of the arm, inside of the forearm and palm, with each location supporting 18 to 32 genera of fungi. Surprisingly, head and trunk body sites ? including the back, back of the neck, inside the ears, behind the ears, and between the eyebrows? have far fewer fungi types, with just two to 10 genera each.

The research team compared fungal diversity data with the skin bacteria on the same healthy adults. They found that while arms have high measures of bacterial diversity, they have lower fungal diversity. They found the reverse to be true for sites on the feet. Core body sites had neither a high bacterial diversity nor a high fungal diversity. The researchers had previously shown that bacterial diversity can be predicted by whether skin is moist, dry or oily. Fungal diversity, instead, seems to depend upon where a particular skin site is on the body.

The researchers observed, in addition, that there is greater similarity in the fungal community structure on the left and right sides of the same person's body compared to the same body parts on any two individuals. Fungal communities also appear to be quite stable over time, with little change when tested on two separate occasions, up to three months apart.

"The data from our study gives us a baseline about normal individuals that we never had before," Dr. Segre said. "The bottom line is your feet are teeming with fungal diversity, so wear your flip flops in locker rooms if you don't want to mix your foot fungi with someone else's fungi."

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Largest Genetic Sequencing Study of Human Disease Completed By Researchers

The exact cause of these diseases - autoimmune thyroid disease, coeliac disease, Crohn's disease, psoriasis, multiple sclerosis and type 1 diabetes- is unknown, but is believed to be a complex combination of genetic and environmental factors. In each disease only a proportion of the heritability is explained by the identified genetic variants. The techniques used to date, have generally identified common (in the population) variants of weak effect.

In this study, using high-throughput sequencing techniques,a global team of scientists sought to identify new variants, including rare and potentially high risk ones, in 25 previously identified risk genes in a sample of nearly 42,000 individuals (24,892 with autoimmune disease and 17,019 controls).

It has been suggested - in the 'rare-variant synthetic genome-wide association hypothesis' - that a small number of rare variants in risk genes are likely to be a major cause of the heritability of these conditions.

However, the study published today in the journal Nature, suggests that the genetic risk of these diseases more likely involves a complex combination of hundreds of weak-effect variants which are each common in the population.

The authors estimate that rare variants in these risk genes account for only around three per cent of the heritability of these conditions that can be explained by common variants.

David van Heel, Professor of Gastrointestinal Genetics at Barts and The London School of Medicine and Dentistry at Queen Mary and director of the Barts and The London Genome Centre, led the study. He said: "These results suggests that risk for these autoimmune diseases is not due to a few high-risk genetic variations but seems rather due to a random selection from many common genetic variants which each have a weak effect.

"For each disease there are probably hundreds such variants and the genetic risk is likely to come from inheriting a large number of these variants from both parents. If this is the case then it may never be possible to accurately predict an individual's genetic risk of these common autoimmune diseases. However, the results do provide important information about the biological basis of these conditions and the pathways involved, which could lead to the identification new drug targets."

The research utilized high-throughput sequencing techniques performed at the Barts and The London Genome Centre and demonstrated for the first time that the sequencing can call genotypes as accurately as 'gold standard techniques' such as genotyping array platforms.

Additional laboratory work was carried out at the Blizard institute at Queen Mary.

Professor Richard Trembath, Vice Principal and Executive Dean for Health at Barts and The London School of Medicine and Dentistry, Queen Mary, and a co-author on the paper said: "The results prompt a re-assessment of the genetic architecture that determines risk for development of common auto-immune disorders and will fuel future careful assessment of regions of the human genome beyond those presently known to confer susceptibility to these important medical conditions."

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