diabetestalk.net

Do Genetics Play A Role In Diabetes?

Genetic Screening For The Risk Of Type 2 Diabetes

Genetic Screening For The Risk Of Type 2 Diabetes

The prevalence and incidence of type 2 diabetes, representing >90% of all cases of diabetes, are increasing rapidly throughout the world. The International Diabetes Federation has estimated that the number of people with diabetes is expected to rise from 366 million in 2011 to 552 million by 2030 if no urgent action is taken. Furthermore, as many as 183 million people are unaware that they have diabetes (www.idf.org). Therefore, the identification of individuals at high risk of developing diabetes is of great importance and interest for investigators and health care providers. Type 2 diabetes is a complex disorder resulting from an interaction between genes and environment. Several risk factors for type 2 diabetes have been identified, including age, sex, obesity and central obesity, low physical activity, smoking, diet including low amount of fiber and high amount of saturated fat, ethnicity, family history, history of gestational diabetes mellitus, history of the nondiabetic elevation of fasting or 2-h glucose, elevated blood pressure, dyslipidemia, and different drug treatments (diuretics, unselected β-blockers, etc.) (1–3). There is also ample evidence that type 2 diabetes has a strong genetic basis. The concordance of type 2 diabetes in monozygotic twins is ~70% compared with 20–30% in dizygotic twins (4). The lifetime risk of developing the disease is ~40% in offspring of one parent with type 2 diabetes, greater if the mother is affected (5), and approaching 70% if both parents have diabetes. In prospective studies, we have demonstrated that first-degree family history is associated with twofold increased risk of future type 2 diabetes (1,6). The challenge has been to find genetic markers that explain the excess risk associated with family history of diabetes Continue reading >>

Genetics & Diabetes : What's Your Risk?

Genetics & Diabetes : What's Your Risk?

A school nurse anxiously wants to know if there is a reason why several children from her small grade school have been diagnosed with type 1 (juvenile onset) diabetes. Is it an epidemic? Will there be more cases? Is a recent chicken pox outbreak to blame? A man in his 50s develops type 2 diabetes. His mother developed diabetes in her 60s. Should this man's brother and sister be concerned, too? What about his children's chances of developing diabetes? A married couple wants to have children, but they are concerned because the husband has type 1 diabetes. They wonder what the risk is that their child would have diabetes. A couple has three young children. One of the children develops type 1 diabetes. There's no history of diabetes anywhere in either parent's families. Is this just a fluke? What are the chances the other children will develop diabetes? Chances are if you or a loved one have diabetes, you may wonder if you inherited it from a family member or you may be concerned that you will pass the disease on to your children. Researchers at Joslin Diabetes Center report that, while much has been learned about what genetic factors make one more susceptible to developing diabetes than another, many questions remain to be answered. While some people are more likely to get diabetes than others, and in some ways type 2 (adult onset diabetes) is simpler to track than type 1 (juvenile onset) diabetes, the pattern is not always clear. For more than 20 years researchers in the Epidemiology and Genetics Section at Joslin in Boston (Section Head Andrzej S. Krolewski, M.D., Ph.D., Senior Investigator James H. Warram, M.D., Sc.D., and colleagues) have been studying diabetes incidence and hereditary factors. They are continuing a scientific journey begun by Elliott P. Joslin, M.D., Continue reading >>

Diabetes Mellitus Type 1 Inheritance

Diabetes Mellitus Type 1 Inheritance

Type 1 diabetes is an inherited condition and individuals with a first degree relative who has the condition are at an increased risk of developing the condition. Details regarding the risk of inheriting type 1 diabetes are given below: In men with type 1 diabetes, the risk of their child also developing the condition is one in 17. In women with type 1 diabetes who have their baby before the age of 25, the risk of the child developing the condition is one in 25. If she has her baby after the age of 25, the risk falls to 1 in 100. If both parents have type 1 diabetes, the risk of the condition developing in offspring varies between 1 in 4 and 1 in 10. The risks are somewhat increased if one of the parents developed type 1 diabetes before the age of 11. Around 1 in 7 people with type 1 diabetes suffer from a condition called type 2 polyglandular autoimmune syndrome and these individuals have parathyroid and adrenal gland disorders in addition to type 1 diabetes. If one of the parents has type 2 polyglandular autoimmune syndrome, the risk that the child will inherit the condition, including type 1 diabetes, is 50%. Genes associated with type 1 diabetes Some genes have repeatedly been identified in people with type 1 diabetes. Among white individuals, examples of such genes include the HLA-DR3 or HLA-DR4 genes. Carrying these genes raises the risk that offspring will inherit type 1 diabetes. Children born with the HLADR3/4-DQ8 genotype make up nearly 50% of all children who develop type 1 diabetes before they are 5 years of age. Some studies on other ethnic groups have shown that similar risks are associated with the HLA-DR7 genotype among African Americans and with the HLA-DR9 gene among Japanese individuals. Genetic studies have also located HLA class II genes at 6p21 and Continue reading >>

Is Diabetes Genetic? Facts About Hereditary Risk

Is Diabetes Genetic? Facts About Hereditary Risk

Diabetes is a complex set of diseases with no single cause. Genetic factors make some people more vulnerable to diabetes, particularly with the right environment. In addition, certain lifestyle factors can cause type 2 diabetes in individuals with no known family history. This complex interaction between genes, lifestyle, and environment points to the importance of taking steps to minimize individual diabetes risk. Is type 1 diabetes hereditary? Type 1 diabetes is an autoimmune disease, which means that it causes the body's immune system to attack healthy cells. It is often called juvenile diabetes because most people are diagnosed in childhood, and the condition then lasts their lifetime. Doctors used to think type 1 diabetes was wholly genetic. Newer studies have shown, however, that children develop type 1 diabetes 3 percent of the time if their mother has the condition, 5 percent of the time if their father has it, or 8 percent if a sibling has type 1 diabetes. Consequently, researchers now believe that something in the environment has to trigger type 1 diabetes. Some risk factors include: Cold weather. People develop type 1 diabetes in winter more frequently than summer. It is also more common in places with cool climates. Viruses. Researchers think some viruses might activate type 1 diabetes in people who are otherwise vulnerable. Measles, mumps, coxsackie B virus, and rotavirus have been linked to type 1 diabetes. Research suggests that people who develop type 1 diabetes may have autoimmune antibodies in their blood for many years before showing symptoms. As a result, the disease may develop over time, or something may have to activate the autoimmune antibodies for symptoms to appear. Is type 2 diabetes hereditary? Type 2 diabetes is the more common form of the d Continue reading >>

Type 2 Diabetes Causes

Type 2 Diabetes Causes

Type 2 diabetes has several causes: genetics and lifestyle are the most important ones. A combination of these factors can cause insulin resistance, when your body doesn’t use insulin as well as it should. Insulin resistance is the most common cause of type 2 diabetes. Genetics Play a Role in Type 2 Diabetes Type 2 diabetes can be hereditary. That doesn’t mean that if your mother or father has (or had) type 2 diabetes, you’re guaranteed to develop it; instead, it means that you have a greater chance of developing type 2. Researchers know that you can inherit a risk for type 2 diabetes, but it’s difficult to pinpoint which genes carry the risk. The medical community is hard at work trying to figure out the certain genetic mutations that lead to a risk of type 2. Lifestyle Is Very Important, Too Genes do play a role in type 2 diabetes, but lifestyle choices are also important. You can, for example, have a genetic mutation that may make you susceptible to type 2, but if you take good care of your body, you may not develop diabetes. Say that two people have the same genetic mutation. One of them eats well, watches their cholesterol, and stays physically fit, and the other is overweight (BMI greater than 25) and inactive. The person who is overweight and inactive is much more likely to develop type 2 diabetes because certain lifestyle choices greatly influence how well your body uses insulin. Lack of exercise: Physical activity has many benefits—one of them being that it can help you avoid type 2 diabetes, if you’re susceptible. Unhealthy meal planning choices: A meal plan filled with high-fat foods and lacking in fiber (which you can get from grains, vegetables, and fruits) increases the likelihood of type 2. Overweight/Obesity: Lack of exercise and unhealthy me Continue reading >>

Genetics Of Type 2 Diabetes

Genetics Of Type 2 Diabetes

Abstract BACKGROUND: Type 2 diabetes (T2D) is a complex disorder that is affected by multiple genetic and environmental factors. Extensive efforts have been made to identify the disease-affecting genes to better understand the disease pathogenesis, find new targets for clinical therapy, and allow prediction of disease. CONTENT: Our knowledge about the genes involved in disease pathogenesis has increased substantially in recent years, thanks to genomewide association studies and international collaborations joining efforts to collect the huge numbers of individuals needed to study complex diseases on a population level. We have summarized what we have learned so far about the genes that affect T2D risk and their functions. Although more than 40 loci associated with T2D or glycemic traits have been reported and reproduced, only a minor part of the genetic component of the disease has been explained, and the causative variants and affected genes are unknown for many of the loci. SUMMARY: Great advances have recently occurred in our understanding of the genetics of T2D, but much remains to be learned about the disease etiology. The genetics of T2D has so far been driven by technology, and we now hope that next-generation sequencing will provide important information on rare variants with stronger effects. Even when variants are known, however, great effort will be required to discover how they affect disease risk. Type 2 diabetes (T2D)2 is a common complex disorder with an increasing prevalence worldwide. In 2010 it was estimated that 6.6% of the world population of individuals 20–79 years old have diabetes, and that T2D constitutes approximately 90% of diabetes cases (1). This number is expected to increase epidemically as a consequence of an aging population and changes Continue reading >>

Type 1 Diabetes

Type 1 Diabetes

Type 1 diabetes is a disorder characterized by abnormally high blood sugar levels. In this form of diabetes, specialized cells in the pancreas called beta cells stop producing insulin. Insulin controls how much glucose (a type of sugar) is passed from the blood into cells for conversion to energy. Lack of insulin results in the inability to use glucose for energy or to control the amount of sugar in the blood. Type 1 diabetes can occur at any age; however, it usually develops by early adulthood, most often starting in adolescence. The first signs and symptoms of the disorder are caused by high blood sugar and may include frequent urination (polyuria), excessive thirst (polydipsia), fatigue, blurred vision, tingling or loss of feeling in the hands and feet, and weight loss. These symptoms may recur during the course of the disorder if blood sugar is not well controlled by insulin replacement therapy. Improper control can also cause blood sugar levels to become too low (hypoglycemia). This may occur when the body's needs change, such as during exercise or if eating is delayed. Hypoglycemia can cause headache, dizziness, hunger, shaking, sweating, weakness, and agitation. Uncontrolled type 1 diabetes can lead to a life-threatening complication called diabetic ketoacidosis. Without insulin, cells cannot take in glucose. A lack of glucose in cells prompts the liver to try to compensate by releasing more glucose into the blood, and blood sugar can become extremely high. The cells, unable to use the glucose in the blood for energy, respond by using fats instead. Breaking down fats to obtain energy produces waste products called ketones, which can build up to toxic levels in people with type 1 diabetes, resulting in diabetic ketoacidosis. Affected individuals may begin breathin Continue reading >>

The Genetics Of Diabetes

The Genetics Of Diabetes

Why me? How did I deserve this? Am I to blame? These are questions that many people ask when diagnosed with a serious condition or disease. Unfortunately, there’s no clear-cut answer when it comes to diabetes. Unlike some traits, diabetes doesn’t seem to be inherited in a simple pattern, and there is a lot of misinformation out there about its causes. (Have you ever had to explain that diabetes doesn’t happen because someone ate too much sugar?) It’s apparent, though, that some people are born more likely to develop diabetes than others. We know that type 1 and type 2 diabetes have different causes, but genetics plays an important role in both types. People with diabetes inherit a predisposition to the disease, then something in their environment triggers it. Identical twins are proof that genes alone are not enough, however. Identical twins have identical genes; therefore, they should have the same genetic risk for a disease—right? Not necessarily. Research has found that if one identical twin has type 1 diabetes, the other twin will get the disease about 50 percent of the time. For type 2 diabetes, that risk rises to as much as 4 in 5. In both type 1 and type 2, identical twins have a much higher risk of both developing diabetes than non-identical (fraternal) twins, which further supports the fact that genetics is involved. So what are the causes of type 1 diabetes? Again, we know that genetics is involved. We also know that it’s not just one gene responsible, but many different genes, each of which contributes only a small part of the risk. Scientists have identified a few genes responsible for type 1, but the majority of the genetic risk is still unidentified. Because of the data about identical twins, we know that type 1 diabetes doesn’t arise solely Continue reading >>

Diabetes And Family History: How Much Risk Is Genetic?

Diabetes And Family History: How Much Risk Is Genetic?

Whether you have Type I or Type II diabetes, there are several factors that could have contributed to the disease. Among these are your family’s lifestyle and your genetic history. By gaining a better understanding of these two issues, you may be able to control your diabetes with more ease, or possibly (in the case of Type II) avoid it altogether. At the very least, understanding the risks created by your genetic and family history will allow you to detect diabetes earlier and avoid the damage it can do if left untreated. How Family Affects Diabetes Risk Your family affects your diabetes risk in two different ways. First, of course, your parents contributed to your genetic heritage. But there’s also the way your parents, your siblings, and your extended family may have influenced the way you eat, exercise, and care for yourself, because these are habits you learn from the people around you as you grow up. Your genetic makeup can play a big role in both Type I and Type II diabetes, while the way a family cares for itself and the habits you’re taught in regard to diet and exercise are generally more related to Type II risk. To help prevent Type II diabetes if you don’t have the disease yet or if you’re prediabetic, there are four questions the NIDDK suggests you ask your family. These are: Does anyone in your family have Type II diabetes and if so, who are they? Has anyone in your family been told they may develop diabetes or are at risk for it? Has anyone in your family been told they need to get more exercise or lose weight in order to prevent diabetes? Did your mother have diabetes when she was pregnant, either with me or with a sibling? Type II diabetes can be greatly affected by the lifestyle a family lives. As you grow up and get older you learn a lot of Continue reading >>

Genetic Abnormalities Linked To Type 2 Diabetes

Genetic Abnormalities Linked To Type 2 Diabetes

RATE★★★★★ Results from genetic studies have shown that heredity (or the genetic material that we inherit through our parents and family) contributes to risk for developing both type 1 and type 2 diabetes. In type 2 diabetes, genetics plays a much stronger role than in type 1 diabetes. A person with a close relative (a child or sibling) with type 1 diabetes has a greater chance of the developing the disease than someone without such a close family history (a 5% to 6% greater risk). However, type 1 diabetes often develops in people with no family history of the disease. This suggests that factors other than genetics probably play a strong role in increasing susceptibility for the disease.1 For type 2 diabetes, your risk for developing the disease is increased if you have a close family member (parent, sibling, or child) who has type 2 diabetes or a medical condition being overweight or obese, having lipid abnormalities, or high blood pressure. In fact, a person with a first-degree relative (parent, sibling, or child) with type 2 diabetes is 5 to 10 times more likely to develop the disease than someone without family history of the disease. Additionally, the risk for developing type 2 diabetes is highest among certain ethnic groups (people of Hispanic, African, or Asian descent).2 How do genes contribute to diabetes susceptiblity? First, let’s define some terms. DNA (deoxyribonucleic acid) is the chemical structure (like a scaffold) that contains all of the genetic information used to make and maintain the body. Our DNA is made up of many individual genes (about 25,000 total). Each gene is a distinct portions of DNA that contains specific instructions for making some substance or structure that the body needs to function. Genes are packaged up in bundles called Continue reading >>

Genetics Of Diabetes And Its Complications

Genetics Of Diabetes And Its Complications

Genetics of Diabetes Type 1 diabetes is the third most prevalent chronic disease of childhood, affecting up to 0.4% of children in some populations by age 30 yr, with an overall lifetime risk of nearly 1% (1,2). It is believed that a large proportion of cases of type 1 diabetes result from the autoimmune destruction of the pancreatic β cells, leading to complete dependence on exogenous insulin to regulate blood glucose levels (3). Type 1 diabetes is strongly clustered in families with an overall genetic risk ratio (the prevalence in siblings of a proband relative to the population prevalence, λS) of approximately 15 (4). (This compares with the less familial but more prevalent type 2 diabetes with λS of approximately 2). At least one locus that contributes strongly to this familial clustering resides within the MHC on chromosome 6p21, which accounts for nearly 40% of the observed familial clustering of type 1 diabetes, with a locus-specific genetic risk ratio (λS) of approximately 3 (5). In a recent analysis of data from three previous genomewide scans (United States, United Kingdom, and Scandinavia) as well as new families collected for the Type 1 Diabetes Genetics Consortium (1435 multiplex families provided evidence for linkage of type 1 diabetes to the MHC (IDDM1), insulin (INS, IDDM2), a region that contains several genes, including CTLA4 (2q31-q33 [IDDM12 and IDDM7]) and seven other chromosome regions (6). The genetic basis for type 2 diabetes has been difficult to resolve. Unlike type 1 diabetes, in which there seems to be an autoimmune process, type 2 diabetes is a disease of relative rather than absolute insulin deficiency. In type 2 diabetes, the pancreatic β cells become progressively less able to secrete sufficient insulin to maintain normal carbohydrat Continue reading >>

Type-2 Diabetes: A Cocktail Of Genetic Discovery

Type-2 Diabetes: A Cocktail Of Genetic Discovery

Type-2 diabetes: a cocktail of genetic discovery Mammalian Genetics Unit, Harwell, Oxfordshire OX11 0RD Mammalian Genetics Unit, Harwell, Oxfordshire OX11 0RD To whom correspondence should be addressed. Email: [email protected] Search for other works by this author on: Human Molecular Genetics, Volume 15, Issue suppl_2, 15 October 2006, Pages R202R209, H. Freeman, R.D. Cox; Type-2 diabetes: a cocktail of genetic discovery, Human Molecular Genetics, Volume 15, Issue suppl_2, 15 October 2006, Pages R202R209, Diabetes is one of the most challenging health problems of the 21st century with an alarming increase in the prevalence of type-2 diabetes mellitus (T2DM) and associated conditions such as hypertension, dyslipidemias and obesity. T2DM is a complex genetic disease comprised of many metabolic disorders with a common phenotype of glucose intolerance. Patients with T2DM would have inherited a variety of different genetic factors that together with environmental factors combine as the primary cause. This complicates the genetic study of the disease and means that different methodological approaches are needed if we hope to identify susceptibility genes and genetic variants. The biochemical and physiological processes that underpin T2DM are still unclear although most certainly involve impairment in insulin secretion and insulin action. In this review, we will discuss the most exciting advances in understanding the genetics of T2DM by looking at recent discoveries employing human association studies and candidate genes arising from animal models. Approximately, 150 million people worldwide are affected by type-2 diabetes mellitus (T2DM), and this figure is expected to double in the next 20 years. Until recently, T2DM was considered to be a disease confined to adulthood, Continue reading >>

Genetics And Type 1 Diabetes

Genetics And Type 1 Diabetes

If you have type 1 diabetes, you might wonder if your child would get it, too. Or if one of your parents has it, what it means for you. Your genes definitely play a role in type 1, a less common form of diabetes that’s often diagnosed in children and young adults. But they’re not the whole story. Like much in life, it’s a mix of nature and nurture. Your environment, from where you grow up to the foods you eat, also matters. Researchers don’t know exactly how -- and how much -- all those things affect your chances of getting the disease. Your genes set the stage, but you can’t be certain how it'll all play out. There’s no diabetes gene that gets turned on or off to give you type 1. Instead, a bunch of them play a role, including a dozen or so that have the biggest say: the HLA genes. They make proteins your immune system uses to keep you healthy. Since type 1 diabetes is an autoimmune disease -- your body destroys the cells that make insulin -- it makes sense that HLA genes are front and center. There are thousands of versions of them in the human gene pool. Which ones you get from your parents affect your chances of diabetes in a big way. Some make you more likely to get it, while others can help protect you from it. You have type 1 if your body makes little or no insulin, a hormone that helps your body turn sugar into energy. Certain genes are more common in one group of people than in another. That’s why race and ethnicity affect things, too. For example, white people are more likely to have type 1 diabetes than others. But even if you have genes that make you more likely to get type 1, that doesn’t mean you definitely will. Even with identical twins -- who have the same exact genes -- sometimes one gets it and the other doesn’t. That’s where the e Continue reading >>

Genetics Of Type 1a

Genetics Of Type 1a

Type 1 diabetes is a complex genetic disorder. There are now at least 20 insulin-dependent genes associated with the development of diabetes. Type 1 diabetes is a complex genetic disorder. It occurs more frequently in families in which there are other relatives with type 1 diabetes and other autoimmune conditions. Children have a 5% to 6% chance of developing diabetes if their father has type 1 diabetes, and a 3% to 4% chance if their mother has type 1 diabetes. It is thought that some of the mother’s chromosomal material, or DNA, gets inactivated when passed on to the child, thereby accounting for the difference in the children’s diabetes risk. If a sibling has type 1 diabetes, the risk is 5-6%; however, if the sibling has identical MHC (Major Histocompatibility Complex) haplotypes, the risk increases. When one identical twin has diabetes, the risk of the other twin developing diabetes traditionally has been thought to be about 40%. Recent research suggests that the number may be much higher. A number of genes have been identified that are associated with the development of diabetes. The chromosomal locations of these “diabetes genes” are called inherited susceptibility loci. There are now at least 20 insulin-dependent diabetes mellitus (IDDM) susceptibility loci. The most important are: IDDM 1 (the major histocompatibility complex on chromosome 6) IDDM 2 (the insulin gene locus on chromosome 11) PTPN 22 (the protein tyrosine phosphatase gene) with a mutation at LYP (the lymphocyte-specific phosphatase gene) on chromosome 1 associated with susceptibility to multiple autoimmune disorders IDDM 1 It is estimated that about 40-50% of the risk for type 1 diabetes is associated with the MHC complex or IDDM 1 loci. The MHC genes most associated with diabetes in white Continue reading >>

Type 2 Diabetes And Dna: Scientists Zero In On The Genetic Signature Of Risk

Type 2 Diabetes And Dna: Scientists Zero In On The Genetic Signature Of Risk

A new discovery helps explain how multiple DNA differences can lead to development of the same disease: type 2 diabetes. Why do some people get type 2 diabetes, while others who live the same lifestyle don’t? For decades, scientists have tried to solve this mystery — and have found more than 80 tiny DNA differences that seem to either raise the diabetes risk in some people or protect others from the disease’s damagingly high blood sugar levels. MORE FROM THE LAB: Subscribe to our weekly newsletter But no one type 2 diabetes signature has emerged from this search. Now, a team of scientists reports a commonality among some diabetes-linked genetic defects, a discovery that might explain how multiple genetic flaws can lead to the same disease. Specifically, the flaws seem to change the way certain cells in the pancreas “read” genes. It’s the first demonstration that many type 2 diabetes-linked DNA changes have to do with the same DNA-reading molecule. Called regulatory factor X, or RFX, it’s a master regulator for a number of genes. The discovery could lead to more personalized treatments for diabetes. The work from the University of Michigan, the National Institutes of Health, the Jackson Laboratory for Genomic Medicine, the University of North Carolina and the University of Southern California is published in the Proceedings of the National Academy of Sciences. Many diabetes-linked DNA changes affect the ability of RFX to bind to specific locations in the genomes of pancreas cell clusters called islets, the team reports. This in turn changes the cells’ ability to carry out important functions. Islets contain the cells that make hormones, including insulin and glucagon, which keep blood sugar balanced in healthy people. In people with diabetes, that regulat Continue reading >>

More in diabetes