<img loading="lazy" decoding="async" class="alignright size-full wp-image-4923" title="Water.vole.arp" src="https://blog-api.23andme.com/wp-content/uploads/2009/10/Water.vole.arp.jpg" alt="Water.vole.arp" width="300" height="335" srcset="https://blogcms.23andme.com/wp-content/uploads/2009/10/Water.vole.arp.jpg 300w, https://blogcms.23andme.com/wp-content/uploads/2009/10/Water.vole.arp-269x300.jpg 269w" sizes="auto, (max-width: 300px) 100vw, 300px" />
Through the millennia wave after wave of migrants &#8211; often in the form of invading armies — have descended upon the British Isles.
The first people to arrive after the Ice Age were hunter-gatherers who followed their prey north from southern Europe about 12,000 years ago. The Celts came from central Europe about 3,000 years ago. Then came the Romans, followed by the Anglo-Saxons, Vikings and finally the Normans in 1066 AD.
With each successive invasion, the previous people were either absorbed by the invaders, or retreated to the isolated corners of the Isles. Often called the &#8220;Celtic Fringe,&#8221; these regions have been studied as a window into the ancient history of the British Isles. Some scholars even propose that the present-day people of the fringe could be direct descendants of the earliest humans to arrive on the Isles after the Ice Age.
But despite exhaustive research into the history and genetics of the Celtic Fringe, its prehistory remains mysterious, forcing scientists to think outside the box. In the September 30 issue of the <a href="http://rspb.royalsocietypublishing.org/content/early/2009/09/25/rspb.2009.1422.abstract">Proceedings of the Royal Society B: Biological Sciences</a>, biologist Jeremy Searle and his research team did just that, devising an unconventional method to study the prehistoric peopling of the British Isles.
They could have examined the DNA of the Celts themselves. But that&#8217;s already been tried, so Searle and his colleagues turned their research underfoot.
Earlier analysis found similar genetic patterns in populations of both common shrews and humans inhabiting the Celtic Fringe. Using those results as a benchmark, Searle and his team expanded the genetic analysis to the pygmy shrew as well as two species of voles.
Searle reasoned that if these shrews and voles had similar immigration patterns to early humans, perhaps those patterns would show up in their DNA. Specifically, he believes that &#8220;this study can help us understand why humans in the British Isles form a Celtic Fringe.&#8221;
Interestingly, Searle and his colleagues&#8217; analysis revealed a division in DNA types for the shrews and voles similar to that separating the people of the Celtic Fringe and the rest of the British population. Further analysis revealed that the DNA types for the mammals living in the Celtic Fringe were quite old. So old, in fact, that Searle and his team propose that the arrival of these mammals traces all the way back to the post-Ice Age arrival of humans 12,000 years ago.
If the mammals living in the Celtic Fringe date back 12,000 years, the people living there could as well.
There is one problem with this hypothesis. The Celts themselves only arrived from mainland Europe 3,000 years ago, not 12,000 years ago. Conventional wisdom states that the Celtic Fringe only evolved after the Celts were pushed back following the invasion of the Romans and Anglo-Saxons.
How does Searle explain this discrepancy? He and his team argue that the Celtic Fringe is not actually Celtic in origin. Rather, its presence predates the arrival of the Celts and their arrival only &#8216;reinforced&#8217; a pre-existing division that was already there.
In that case, it would have been the Celts themselves whose arrival pushed earlier inhabitants to the isolated corners of the British Isles. Subsequent migrations would have pushed the Celts into these same corners, which is why the language and culture of these regions are inherently Celtic. And that would also explain why the languages, culture, and history of the pre-Celtic people of Britain have mostly been lost to time.

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23andMe Blog Team

Shrews and Voles Reveal Clues to British Prehistory

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Inflammatory bowel disease (IBD), which can appear as either ulcerative colitis or Crohn&#8217;s disease, damages the lining of the digestive tract and leads to abdominal cramps, incomplete digestion and nutritional deficiencies.
Previous research on IBD gave researchers reason to suspect that the CD39 gene, which is involved with inflammatory responses and immunity, may play a role in IBD. Researchers at Harvard University, led by Simon Robson, found further evidence for this gene&#8217;s involvement when they removed it from a group of mice. Compared to normal animals, the genetically engineered mice were more susceptible to a drug that causes colitis symptoms similar to those experienced by humans. The results were published this week in the <a href="https://www.pnas.org/content/early/2009/09/28/0902869106.abstract?sid=2e91c093-2dd0-487b-908b-8f63dc01097c" target="_blank" rel="noopener">Proceedings of the National Academy of Sciences</a>.
With these animal model results in hand, the researchers turned their attention to humans. They searched a database of genetic information for DNA variants that are predicted to affect how much protein is made from the CD39 gene. One SNP in particular stood out. Not only did the A version of this SNP correlate with lower CD39 protein levels, but it was also associated with risk for Crohn&#8217;s disease. The researchers determined that one copy of the A version of this SNP increased the odds of Crohn&#8217;s disease by 1.14 times, while two copies increased the odds by 1.3 times.

Although the study focused only on Europeans, the authors believe their results will also be relevant to people of other ethnicities. The A version of that is associated with increased odds for Crohn&#8217;s disease in Europeans is also associated with lower levels of CD39 protein in people with African, Chinese and Japanese ancestry. The importance of this SNP may vary among ethnic groups, however, because the prevalence of the A version differs.
The researchers suggest that future studies will help define exactly how CD39 influences IBD and identify other SNPs that may influence risk for the disease.

Genetic Clues to Bowel Disease Found in Mice and Men

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In the United States, prostate cancer affects about one in every six men.   Genomewide association studies to find common genetic variants associated with this disease have been particularly successful. 



More than a dozen SNPs have been associated with prostate cancer, but researchers calculate that these variants represent only a tiny fraction of the genetic component of the disease.



<h2 class="wp-block-heading" id="h-filling-the-gap">Filling the Gap</h2>



To fill in the genetic gaps, researchers are turning to studies that include larger numbers of participants than ever before.   The hard work is paying off, as seen in four recent reports of Nature Genetics.   These analyses, based on the DNA of tens of thousands of men, have added at least 12 new variants to the roster of prostate cancer-associated SNPs.



One of the most striking features of these new studies is that they have identified two new SNPs on chromosome eight in a region known as 8q24.   Three other variants in this same region have already been linked to prostate cancer in both African American and European samples.   Other SNPs in the 8q24 region have been associated with breast, bladder, and colorectal cancer.<wp-block data-block="core/more"></wp-block>



The bounty of cancer-related SNPs in the 8q24 region is puzzling to scientists because there are no actual genes in this stretch of DNA.   The closest gene, MYC, is known to be involved in cancer, but so far, there is no evidence that the cancer-associated 8q24 SNPs are affecting MYC. Future research will hopefully identify what these SNPs are doing and how they affect cancer risk.



<h2 class="wp-block-heading" id="h-gwas-limitations">GWAS Limitations</h2>



Even though prostate cancer genome-wide association studies have been fruitful, critics such as John Witte of UCSF argue that the findings may not be clinically useful (read his February Nature Genetics review of prostate cancer genomics <a href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pubmed&amp;pubmedid=19104501" target="_blank" rel="noopener noreferrer">here</a>).



But that doesn&#8217;t mean that looking for variants associated with prostate cancer should be abandoned. &nbsp; Finding SNPs associated with the disease could lead scientists to new treatments.



There is also the possibility of finding variants that don&#8217;t just predict whether someone is at risk for prostate cancer but whether they are at risk for a particularly aggressive form of the disease. This could <a href="https://www.forbes.com/2009/08/31/prostate-cancer-screening-business-healthcare-prostate.html" target="_blank" rel="noopener noreferrer">help doctors discriminate</a> between those men whose cancers require immediate treatment and those who can avoid the side effects of surgery and radiation in favor of &#8220;watchful waiting.&#8221;



&#8220;There is clear clinical utility in identifying markers that can distinguish which prostate tumors will progress rapidly and be life-threatening versus those that are relatively latent and may not substantively impact a man&#8217;s health,&#8221; Witte writes.



<h2 class="wp-block-heading" id="h-more-data-needed">More Data Needed</h2>



As has been the case with most other studies looking for genetic variants associated with prostate cancer, none of the four new studies found an association between the identified SNPs and disease severity. Scientists have suggested that this indicates the studies are mainly finding variations associated with increased risk for cancer initiation. 



More large studies will be needed to find disease aggression-associated variants, and researchers will need to focus on SNPs correlated with disease recurrence following treatment and/or mortality instead of just the presence or absence of disease.

Researchers Find More Genetic Variants Associated With Prostate Cancer

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For as long as humans have lived in complex communities, cities and civilizations, they have divided and classified their societies. Those divisions have been based on age, gender, appearance or &#8211; in many cases &#8211; occupation. In many traditional societies artisans would share the same social status; as would soldiers, priests and workers in any number of other occupations.
<h6>Social Stratification</h6>
In antiquity, the status of a family rarely changed. If you were a farmer, your sons would be farmers, and so on. While today social status barriers are crumbling in many societies, in others they remain largely unchanged.
India&#8217;s complex social stratification, known as the caste system, has been one of the traditional cornerstones of society. Though urban Indians are shedding the caste labels of their parents and grandparents, many rural Indians &#8211; who make up 72% of the entire population &#8211; hold steadfast to the system. In small villages and towns, the Brahmin caste &#8211; consisting of scholars and priests &#8211; is still revered as one of the highest social strata. And members of the Dalit caste &#8211; formerly known as &#8220;Untouchables&#8221; &#8211; are still viewed as unclean and remain separated from others.
The rigidity of the system still present in rural India has made many wonder exactly how long castes have existed. Historical records are unclear, as early Hindu scriptures like the Bhagavad Gita are somewhat ambiguous when it comes to the topic. Some historians even propose that the caste system as we know it today is largely a construct of the English Colonial Era, arguing that the development of such a system could have been deemed necessary to instill order.
<h6>Genetic Analysis</h6>
Genetic analysis has also proven inconclusive, as analysis of small segments of the human genome has yielded different results. But a new study by geneticist David Reich and colleagues, published in the September 24 issue of <a href="https://www.nature.com/nature/journal/v461/n7263/abs/nature08365.html" target="_blank" rel="noopener">Nature</a>, takes a new approach to understanding the genetic history of India.
The core difference between Reich&#8217;s genetic analysis and previous studies is in the sheer amount of genetic material analyzed. Reich&#8217;s team examined more than 550,000 points across all segments of the human genome. In doing so, they hoped to obtain a more complete picture of Indian genetic history.
The research team analyzed the DNA of 132 individuals from India and neighboring regions, dividing them into 25 distinct groups based on geography, caste and language. They calculated how genetically &#8216;closed&#8217; each of these groups were. In the caste system it is rare to marry someone from another class, making caste societies very closed, or &#8216;endogamous.&#8217; If this endogamy continues over many generations, it will leave a behind a genetic signature for scientists to discover.
Reich and his team found such a signature, indicating a long history of endogamy in several of the groups. In fact, the research team calculated that the DNA of six of the groups can be traced back to just a few individuals who lived anywhere from 30 to more than 100 generations ago. Assuming a generation time of 25 years, that establishes the existence of the caste system in the range of 750 to more than 2,500 years ago – long before the British colonial era.
In a second analysis, Reich and his team examined how ancient migrations could have influenced the formation of castes. First the researchers divided the Indian groups into language families: Indo-European and Dravidian. Dravidian tongues, like Tamil and Malayalam, are mainly spoken in southern India and are believed to be a remnant of languages spoken by some of the earliest inhabitants of the region. Indo-European languages, like Punjabi and Urdu, are more common in the north. They are believed to have arrived with a migration of farmers from southwestern Asia or the Near East about 9,000 years ago.
Reich and his colleagues then compared the genetics of each of the Dravidian and Indo-European groups to a sample of European DNA. The team reasoned that, if Indo-European groups were really descended from the farmers, they would show more genetic similarity to the Europeans than the Dravidians.
Not surprisingly, the authors&#8217; hypothesis held true. The Indo-European speakers, like the Kashmiri Pandit and Vaish, were more genetically similar to Europeans. And because the majority of the upper castes speak Indo-European languages, while the lower ones tend to be Dravidian speakers, there could be a relationship between the arrival of Indo-European people and the formation of caste structure. Further evidence that an ancient caste system has permeated through India for thousands of years.

New Genetic Analysis Sheds Light on Origins of Indian Castes

<div id="attachment_4791" style="width: 360px" class="wp-caption alignright"><img loading="lazy" decoding="async" aria-describedby="caption-attachment-4791" class="wp-image-4791 size-full" title="Glaucoma" src="https://blog-api.23andme.com/wp-content/uploads/2009/09/Glaucoma.jpg" alt="Glaucoma" width="350" height="206" srcset="https://blogcms.23andme.com/wp-content/uploads/2009/09/Glaucoma.jpg 350w, https://blogcms.23andme.com/wp-content/uploads/2009/09/Glaucoma-300x177.jpg 300w" sizes="auto, (max-width: 350px) 100vw, 350px" />Credit: National Eye Institute, National Institutes of Health</div>
Glaucoma is the second leading cause of blindness and is estimated to affect over 66 million people worldwide.
This group of diseases is typically caused by increased pressure in the eye, which slowly damages the optic nerve and leads to gradual vision loss and eventual, incurable blindness if left untreated.
The most common form of glaucoma is primary open-angle glaucoma or POAG. Prevalence of POAG among Caucasians is approximately 1-2%, but those with African ancestry develop glaucoma at rates five times higher and are four times more likely to become blind once they have the disease.
<h6> Glaucoma in Families</h6>
Family history and advanced age, in addition to high intraocular pressure, are known risk factors. Studies of families and monozygotic twins suggest a genetic basis, though the specific genes involved in the majority of disease cases have remained elusive.
To explore the genetic underpinnings of POAG in individuals of African descent, a group of researchers led by Xiaodong Jiao from the National Eye Institute in Bethesda and Kang Zhang from the University of California &#8211; San Diego recently partnered with the Ministry of Health in Barbados, West Indies to search for genetic variants associated with POAG in an Afro-Caribbean population with high rates of glaucoma.
<h6>New Study</h6>
In their paper, published online this week in the <a href="https://www.pnas.org/content/early/2009/09/23/0907564106.abstract">Proceedings of the National Academy of Sciences</a>, they report results from a region of the genome, chromosome 2p16, that previous studies have linked to the disease. When they analyzed SNPs in this region of the genome for the Barbados study group, they found two common variants significantly associated with glaucoma.
Although the case-control study population was fairly small &#8211; about 252 individuals total with glaucoma and 130 controls &#8211; the effects of the two SNPs were large when individuals had two copies of the high-risk version. Individuals with a T at both copies of had about 7 times higher odds of glaucoma, while individuals with a T at both copies of had almost 35 times higher odds.
The authors note that while their analysis of the 2p16 region suggests multiple genetic bases for POAG in Afro-Caribbeans, this region overlaps with one that was shown to contribute unequivocally to POAG in some families. They posit that the severity of the mutations caused by different variants in this genomic area may influence whether resulting POAG is due to a single gene, or the combined effects of many genes acting together to increase risk.
Further studies are needed to confirm the associations of and with POAG in larger populations, and to identify the genes directly involved in development of glaucoma.
(SNPwatch gives you the latest news about research linking various traits and conditions to individual genetic variations. These studies are exciting because they offer a glimpse into how genetics may affect our bodies and health; but in most cases, more work is needed before this research can provide information of value to individuals. For that reason it is important to remember that like all the information we provide, the studies we describe in SNPwatch are for research and educational purposes only. SNPwatch is not intended to be a substitute for professional medical advice; you should always seek the advice of your physician or other appropriate healthcare professional with any questions you may have regarding diagnosis, cure, treatment or prevention of any disease or other medical condition.)
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SNPwatch: Common Variants May Influence Glaucoma Risk in Individuals of African Descent

Human Prehistory 101:  Out of (Eastern) Africa

Alcohol addiction is associated with the brain’s reward system, which reinforces behaviors that feel good – like drinking – by releasing neurotransmitters such as dopamine and endorphins. With prolonged alcohol consumption, a person&#8217;s brain can gradually adapt to the point that excessive amounts of drinking are required in order to produce the same pleasure response, and alcohol addiction results.
That means genetic factors that influence the biochemistry of the reward pathway, as well as environmental factors that encourage alcohol consumption (such as peer pressure and stress) can increase a person&#8217;s alcoholism risk.
Researchers have long suspected that a combination of genetic and environmental causes can act together, increasing risk of alcohol addiction more than either acting alone. But so far little evidence has been found for such an effect.

A new paper to be published in the December issue of Alcoholism: Clinical and Experimental Research has found evidence for a synergistic effect between a genetic variation and level of education in a study of 700 Mexican-Americans. The prevalence of alcohol addiction among Mexican-Americans is relatively high; Mexican-American men report past heavy drinking at three times the rate of men belonging to other ethnicities.
The researchers, Yanlei Du and Yu-Jui Yvonne Wan of the University of Kansas Medical Center, measured three genetic variants associated with the function of chemicals involved in the brain&#8217;s reward system. They also looked at marital status and education level in the study participants.
The study found that of the three genetic variants, two were associated with severe alcoholism (defined by consuming more than 35 drinks per day).
o Having two copies of the A version of one of the SNPs, which is located on the opioid receptor gene OPRM1, increased the odds of severe alcoholism 2.16 times. 
o Having two copies of a variant in the DRD2 gene, which affects the structure of a receptor for the neurotransmitter dopamine, increased the risk of severe alcoholism 1.85 times.
Of the two environmental factors, only education level had an effect. Those with less than 12 years of education had 1.97 times the odds of severe alcoholism. (Having less than 12 years of education also increased a person&#8217;s odds of less-severe alcoholism by about the same amount.)
But when the researchers considered combinations of the three associations, they found that having two A copies of the OPRM1 SNP , combined with less than 12 years of education, increased a person&#8217;s odds of severe alcoholism 3.3 times.
The researchers suggest that a low education level may magnify the effects of the OPRM1 variant, or that higher education may mask its effects by improving brain function.
However, other factors might be responsible for the effect. For example, it is possible that those who attain an education past high school have other characteristics that make them less likely to become addicted to a substance.
There is no way yet to measure an individual’s vulnerability to alcohol addiction, and the complex interaction between genetics, education and other environmental factors must be further studied to clarify the causes of alcoholism in this and other ethnicities.

Evidence for Gene-Environment Interaction in Alcohol Addiction

<img loading="lazy" decoding="async" class="alignright size-full wp-image-4747" title="800px-HCV_prevalence_1999" src="https://blog-api.23andme.com/wp-content/uploads/2009/09/800px-HCV_prevalence_1999.png" alt="800px-HCV_prevalence_1999" width="433" height="189" srcset="https://blogcms.23andme.com/wp-content/uploads/2009/09/800px-HCV_prevalence_1999.png 800w, https://blogcms.23andme.com/wp-content/uploads/2009/09/800px-HCV_prevalence_1999-300x132.png 300w, https://blogcms.23andme.com/wp-content/uploads/2009/09/800px-HCV_prevalence_1999-768x337.png 768w" sizes="auto, (max-width: 433px) 100vw, 433px" />
Unlike the flu virus, which the body is generally able to fight off completely, infection with hepatitis C is often chronic.   That means for most of the three to four million people worldwide who are newly infected each year the virus will persist in the body, where it greatly increases risk for chronic liver diseases including cirrhosis and cancer. The only treatment currently available – an almost year long course of drugs – often causes severe side-effects. Worse yet, it fails in about half of all patients.
Last month, a <a href="https://dx.doi.org/10.1038/nature08309" target="_blank" rel="noopener noreferrer">study</a> published online in the journal Nature showed that DNA variations in and around the IL28B gene influence whether a person chronically infected with the hepatitis C virus will fully respond to the standard treatment regimen. Now three new reports further support the importance of IL28B variations in the body&#8217;s response to hepatitis C, a finding that has implications for the future of hepatitis treatment and drug development.
An Australian group headed up by <a href="https://dx.doi.org/10.1038/ng.447" target="_blank" rel="noopener noreferrer">Vijayaprakash Suppiah</a> analyzed the DNA of more than 800 people with European ancestry from Australia, the UK, Germany and Italy infected with hepatitis C.   They found that having one or two copies of the less-common G version of , a SNP near the IL28B gene, doubled the odds that a person would fail to have a sustained response to treatment.
A group headed up by <a href="https://dx.doi.org/10.1038/ng.449" target="_blank" rel="noopener noreferrer">Yasuhito Tanaka</a> studied 326 Japanese hepatitis C patients and also found that predicts whether or not a person will respond to treatment.   In this population, however, the effect was much greater.   Carrying a G increased the odds of treatment failure by at least twelve times.
&#8220;This SNP has such a strong association with response that, in combination with other parameters, genotyping it and other genetic variants should be a useful part of   clinical management,&#8221; write Suppiah et al., who along with Tanaka et al. published their results online this week in the journal Nature Genetics.
Another study, this one published online in <a href="https://dx.doi.org/10.1038/nature08463" target="_blank" rel="noopener noreferrer">Nature</a>, found that variation near IL28B might be part of what allows a minority of people infected with hepatitis C to clear the virus naturally, without any treatment.
David Thomas and colleagues found that individuals with European or African ancestry were about three times more likely to spontaneously clear a hepatitis C infection if they carried two copies of the C version of than if they had CT or TT at this SNP.
Twenty-eight percent of the people with the CT or TT genotypes were able to fight off their hepatitis C infection without treatment, a number very close to the population average.   But 53% of those with the CC genotype were able to become naturally virus-free.
In a <a href="https://dx.doi.org/10.1038/461357a" target="_blank" rel="noopener noreferrer">commentary published in Nature</a>, Shawn Iadonato and Michael Katze express doubts about the importance of these new discoveries.
&#8220;Although these findings raise the tantalizing prospect of a more personalized approach to treating [hepatitis C] by tailoring treatment to patients who are most likely to benefit, the reality is more sobering,&#8221; they write.
Iadonato and Katze worry that testing for IL28B variations would not provide doctors with a straightforward yes-or-no answer to the question of whether a patient will respond to hepatitis C treatment.   This is because not all carriers of the advantageous versions of the variants clear the virus, nor do all patients lacking them fail to benefit from treatment.   Furthermore, they point out, there is currently no alternative hepatitis C treatment available.
What they do not consider, however, is how this new research may help change that. In a separate <a href="https://dx.doi.org/10.1038/ng.453" target="_blank" rel="noopener noreferrer">commentary in Nature Genetics</a>, Thomas O&#8217;Brien suggests that the current findings could increase the interest in developing hepatitis therapies based on the protein encoded by IL28B, interferon-Î»3.   He notes that an early clinical trial testing the effects of a related protein, interferon-Î»1, has already had some success.   And certain properties of interferon-Î»s may cause them to have fewer side effects than current treatments.
O&#8217;Brien is still cautious about the findings linking IL28B variations to hepatitis C treatment response.   He says that more research in this area is needed in diverse populations and in people infected with different forms of hepatitis C.   He also stresses that researchers need to consider how these genetic findings fit in with other factors that affect treatment response, including age and gender.
Overall, however, his view is optimistic.   He concludes: &#8220;With these caveats, predictive models of HCV treatment response hold the potential to inform treatment decisions for millions of patients who are infected with HCV.&#8221;
Map: <a href="https://en.wikipedia.org/wiki/File:HCV_prevalence_1999.png" target="_blank" rel="noopener noreferrer">PhilippN</a>

More Evidence That Genetic Variations are Important for Hepatitis C Infection and Treatment

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New research suggests the primary genetic mutation that causes alpha-1 antritrypsin deficiency, a condition that results in liver damage and a wide variety of other problems, also affects risk for liver disorders associated with cystic fibrosis.
Cystic fibrosis is an inherited, childhood-onset disorder that causes the <a href="https://blog.23andme.com/articles/snpwatch-genetic-variation-that-reduces-immune-cell-activity-may-lessen-severity-of-lung-damage-in-cystic-fibrosis-patients/" target="_blank" rel="noopener noreferrer">lungs</a>, intestines and pancreas to become clogged with mucus, resulting in breathing and digestive problems. Between three and five percent of CF patients also experience liver disease, which leads to scarring that can block blood flow through the organ and increase blood pressure in surrounding vessels.
Liver transplants have been necessary in many of these cases, but the new genetic research may be able to help prevent them by enabling prediction and prevention of CF-associated liver disease.

A team of researchers at the University of North Carolina at Chapel Hill, led by Michael Knowles, analyzed genetic variants in five genes that have been proposed to be involved in cystic fibrosis-related liver disease. The study involved nearly 1,000 patients, both with and without liver symptoms.
The results, published last week in the <a href="http://jama.ama-assn.org/cgi/content/short/302/10/1076?rss=1" target="_blank" rel="noopener noreferrer">Journal of the American Medical Association</a>, identified one genetic variation that increases a cystic fibrosis patient’s risk of developing liver disease. Researchers found that each T at the SNP increases odds of liver disease in CF patients by 4.17 times. A T at both copies of this SNP causes <a href="http://www.chestjournal.org/content/122/5/1818.full" target="_blank" rel="noopener noreferrer">alpha-1 antitrypsin deficiency</a>.
Researchers are still searching for genetic variations associated with other complications of cystic fibrosis, including lung disease, intestinal obstruction and diabetes. Further studies on severe liver disease related to cystic fibrosis may reveal more risk factors for severe symptoms that can be detected early in life.

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