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Is Diabetes A Genetic Disorder

Defining The Genetic Contribution Of Type 2 Diabetes Mellitus

Defining The Genetic Contribution Of Type 2 Diabetes Mellitus

Diabetes mellitus (DM) affects over 150 million people world wide, with a prevalence that varies markedly from population to population.1 Estimates predict that almost 300 million people will suffer from DM by 2025 (fig 1) with the vast majority being cases of diabetes mellitus type 2. Many risk factors have been identified which influence the prevalence (total number of cases as a percentage of the total population) or incidence (total number of new cases per year as a percentage of the total population). Factors of particular importance are a family history of diabetes mellitus, age, overweight, increased abdominal fat, hypertension, lack of physical exercise, and ethnic background. Several biochemical markers have also been identified as risk factors, including fasting hyperinsulinaemia, increased fasting proinsulin, and decreased HDL cholesterol.2 Both diabetes mellitus types 1 and 2 show a familial predisposition, which is a strong indication for the involvement of genes in people's susceptibility to the disease. However, the aetiology underlying types 1 and 2 is different and different genes are likely to be involved in each type of diabetes mellitus. The following discussion focuses on a genetic dissection of type 2 diabetes mellitus. The two most common forms of diabetes mellitus, type 1 and type 2, are both characterised by raised plasma glucose levels. Normal glucose homeostasis depends on the balance between glucose production by the liver and kidneys and glucose uptake by the brain, kidneys, muscles, and adipose tissue. Insulin, the predominant anabolic hormone involved, increases the uptake of glucose from the blood, enhances its conversion to glycogen and triglyceride, and also increases glucose oxidation. Plasma glucose levels are normally kept within a s Continue reading >>

Is Type 2 Diabetes A Genetic Disorder?

Is Type 2 Diabetes A Genetic Disorder?

Type 2 diabetes mellitus or Non−insulin−dependent diabetes (NIDDM) is a common disorder characterised by high blood glucose levels, which, if untreated, can cause serious medical complications such as cardiovascular diseases, heart attack, reduced life expectancy, loss of limbs and stroke. Worldwide, this diabetes affects more than 135 million people. Genetic factors of an individual play an important role in the development of diabetes. Some types of diabetes are caused by mutations in a single gene and others are multi-factorial in origin. Regrettably, the number of genes involved, their chromosomal location and the degree of their effect on a diabetic are unknown. Type 2 diabetes is not a genetic disease scientifically, but has a stronger link to family history than type 1 diabetes. Development of NIDDM depends on obesity and various environmental factors. Obesity tends to run in families and, usually, all family members have similar eating habits, exercise habits and lifestyle. If you have a family history of type 2 diabetes, you may find difficulty in figuring out whether your diabetes is due to lifestyle factors, genetic factors or both. Type 2 diabetes can be prevented by lifestyle changes though some people have a strong genetic link. Occurrence of type 2 diabetes in a person can have some link to his/her family history, but not a very strong one. If you were diagnosed with type 2 diabetes before the age of 50, the risk of your child getting diabetes is 1 in 7. If you were diagnosed after 50, risk in your children becomes 1 in 13. If the parents have type 2 diabetes, the risk of the child getting it becomes 50%.General population has only 5% risk of developing type 2 diabetes. In case of identical twins, if one sibling is type 2 diabetic, the other will have Continue reading >>

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 >>

Type 1 Diabetes Risk Factors

Type 1 Diabetes Risk Factors

There are several risk factors that may make it more likely that you’ll develop type 1 diabetes—if you have the genetic marker that makes you susceptible to diabetes. That genetic marker is located on chromosome 6, and it’s an HLA (human leukocyte antigen) complex. Several HLA complexes have been connected to type 1 diabetes, and if you have one or more of those, you may develop type 1. (However, having the necessary HLA complex is not a guarantee that you will develop diabetes; in fact, less than 10% of people with the “right” complex(es) actually develop type 1.) Other risk factors for type 1 diabetes include: Viral infections: Researchers have found that certain viruses may trigger the development of type 1 diabetes by causing the immune system to turn against the body—instead of helping it fight infection and sickness. Viruses that are believed to trigger type 1 include: German measles, coxsackie, and mumps. Race/ethnicity: Certain ethnicities have a higher rate of type 1 diabetes. In the United States, Caucasians seem to be more susceptible to type 1 than African-Americans and Hispanic-Americans. Chinese people have a lower risk of developing type 1, as do people in South America. Geography: It seems that people who live in northern climates are at a higher risk for developing type 1 diabetes. It’s been suggested that people who live in northern countries are indoors more (especially in the winter), and that means that they’re in closer proximity to each other—potentially leading to more viral infections. Conversely, people who live in southern climates—such as South America—are less likely to develop type 1. And along the same lines, researchers have noticed that more cases are diagnosed in the winter in northern countries; the diagnosis rate 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 >>

New Analysis Concludes Cause Of Diabetes Not Genetic

New Analysis Concludes Cause Of Diabetes Not Genetic

Since sequencing the human genome, genetic researchers have searched intensively but unearthed little evidence to suggest that inherited genes cause common diseases…. For such diseases, which include heart disease, stroke, cancers, diabetes, and disorders such as autism, ADHD and dementia, as well as mental illnesses such as schizophrenia and depression, significant genetic causation can now be ruled out with a high degree of confidence. The case for a substantial role of genes in susceptibility to the major human diseases is now scientifically refuted argues a groundbreaking new analysis published by the public interest science organization, The Bioscience Resource Project. The analysis stems from the repeated failure of a new and comprehensive genome scanning method (called Genome-Wide Association studies, GWA studies) to find important human disease genes. It notes that more than 700 GWA studies by researchers from all over the world, covering over 80 different diseases and at a cost of many billions of dollars, have yielded essentially the same result. Of the approximately 1,000 genes identified that confer susceptibility to disease only a tiny handful are of even limited importance. The remainder are so weak in their effects as to be of negligible significance to human health1. “Geneticists are repeatedly finding only genes with trivial effects, but since they have a strong incentive not to declare this search over, they are left invoking unlikely hiding places for the important disease genes they have always predicted,” says Jonathan Latham, Executive Director of the Bioscience Resource Project2. The Great DNA Data Deficit: Are genes for disease a mirage? which will be published on December 9th, 2010, points out that the hiding places on which geneticists’ Continue reading >>

What Is Type 2 Diabetes?

What Is Type 2 Diabetes?

Diabetes is a disease that's characterized by high blood sugar, which doctors refer to as hyperglycemia. In type 2 diabetes, the two main contributors to high blood sugar are insulin resistance and a drop in your body's production of insulin. These two factors are what makes type 2 diabetes different from type 1 diabetes, gestational diabetes, and other types of diabetes. What Is Insulin Resistance? Insulin — the hormone that allows your body to regulate sugar in the blood — is made in your pancreas. Insulin resistance is a state in which the body’s cells do not use insulin efficiently. As a result, it takes more insulin than normal to transport glucose (the main type of sugar found in the bloodstream) into cells, where it can be used for fuel or stored for later use. Insulin resistance develops over time, and as the body becomes more and more insulin resistant, the pancreas responds by releasing more and more insulin. This higher-than-normal level of insulin in the bloodstream is called hyperinsulinemia. For a while, the pancreas may be able to keep up with the body’s increased need for insulin, and blood sugar levels may stay within the normal range — about 70 to 100 mg/dl before meals and lower than 140 mg/dl after meals. Eventually, however, the pancreas can no longer keep up, and blood sugar levels begin to rise. What Causes Type 2 Diabetes? It's not known for certain why some people develop type 2 diabetes and some do not. There are several factors, however, that can increase a person's risk of developing type 2 diabetes: Obesity Being obese or overweight puts you at significant risk for developing type 2 diabetes. Four out of five people with type 2 diabetes are overweight or obese. Prediabetes Prediabetes is a condition in which your blood sugar levels Continue reading >>

Type 1 Diabetes

Type 1 Diabetes

Type 1 diabetes is the type of diabetes that typically develops in children and in young adults. In type 1 diabetes the body stops making insulin and the blood sugar (glucose) level goes very high. Treatment to control the blood glucose level is with insulin injections and a healthy diet. Other treatments aim to reduce the risk of complications. They include reducing blood pressure if it is high and advice to lead a healthy lifestyle. What is type 1 diabetes? What is type 1 diabetes? Play VideoPlayMute0:00/0:00Loaded: 0%Progress: 0%Stream TypeLIVE0:00Playback Rate1xChapters Chapters Descriptions descriptions off, selected Subtitles undefined settings, opens undefined settings dialog captions and subtitles off, selected Audio TrackFullscreen This is a modal window. Beginning of dialog window. Escape will cancel and close the window. TextColorWhiteBlackRedGreenBlueYellowMagentaCyanTransparencyOpaqueSemi-TransparentBackgroundColorBlackWhiteRedGreenBlueYellowMagentaCyanTransparencyOpaqueSemi-TransparentTransparentWindowColorBlackWhiteRedGreenBlueYellowMagentaCyanTransparencyTransparentSemi-TransparentOpaqueFont Size50%75%100%125%150%175%200%300%400%Text Edge StyleNoneRaisedDepressedUniformDropshadowFont FamilyProportional Sans-SerifMonospace Sans-SerifProportional SerifMonospace SerifCasualScriptSmall CapsReset restore all settings to the default valuesDoneClose Modal Dialog End of dialog window. Diabetes mellitus (just called diabetes from now on) occurs when the level of sugar (glucose) in the blood becomes higher than normal. There are two main types of diabetes. These are called type 1 diabetes and type 2 diabetes. Type 1 diabetes usually first develops in children or young adults. In the UK about 1 in 300 people develop type 1 diabetes at some stage. With type 1 diabet 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 >>

Genetic Disorder May Reveal How Statins Boost Diabetes Risk

Genetic Disorder May Reveal How Statins Boost Diabetes Risk

Millions of people take statins to lower their cholesterol and reduce the risk of cardiovascular disease. But taking statins does slightly up the risk of Type 2 diabetes. Figuring out whether that means "No statins for you" isn't always easy, despite a proliferation of guidelines intended to help. Here's in interesting wrinkle: If you've got a hereditary form of high cholesterol you're much less likely to get Type 2 diabetes, according to a study published Tuesday in JAMA, the journal of the American Medical Association. That's good news for those people, who often have high levels of LDL cholesterol starting in childhood and face a high risk of heart disease and stroke. And it offers intriguing hints as to a possible link between cholesterol receptors in the body and Type 2 diabetes. To find that out, researchers in the Netherlands delved into an amazing database that has tracked people for familial hypercholesterolemia since 1994. The large number of people tested — 63,320 — made it possible to not only identify people with genetic mutations that caused the high cholesterol, but to show how it runs in families. The people with familial hypercholesterolemia had a 51 percent lower risk of Type 2 diabetes than their relatives without the disorder. But the diabetes risk for both groups was low: 1.75 percent versus 2.93 percent. It varied based on the particular genetic mutation involved. That difference makes for a nifty demonstration on how genes affect risk, and confirms a link that doctors who treat patients with the disorder have long observed. And it also may explain why taking statins boosts the risk of Type 2 diabetes in some people. One theory on how statins work is that they encourage cells to hoover up the bad LDL cholesterol by turning on LDL receptors. Tha Continue reading >>

Genetic Causes Of Diabetes Mellitus Type 2

Genetic Causes Of Diabetes Mellitus Type 2

Most cases of diabetes mellitus type 2 involved many genes contributing small amount to the overall condition.[1] As of 2011 more than 36 genes have been found that contribute to the risk of type 2 diabetes.[2] All of these genes together still only account for 10% of the total genetic component of the disease.[2] There are a number of rare cases of diabetes that arise due to an abnormality in a single gene (known as monogenic forms of diabetes).[1] These include maturity onset diabetes of the young (MODY), Donohue syndrome, and Rabson–Mendenhall syndrome, among others.[1] Maturity onset diabetes of the young constitute 1–5% of all cases of diabetes in young people.[3] Polygenic[edit] Genetic cause and mechanism of type 2 diabetes is largely unknown. However, single nucleotide polymorphism (SNP) is one of many mechanisms that leads to increased risk for type 2 diabetes. To locate genes and loci that are responsible for the risk of type 2 diabetes, genome wide association studies (GWAS) was utilized to compare the genomes of diabetic patient group and the non-diabetic control group.[4] The diabetic patients’ genome sequences differ from the controls' genome in specific loci along and around numerous genes, and these differences in the nucleotide sequences alter phenotypic traits that exhibit increased susceptibility to the diabetes. GWAS has revealed 65 different loci (where single nucleotide sequences differ from the patient and control group's genomes), and genes associated with type 2 diabetes, including TCF7L2, PPARG, FTO, KCNJ11,NOTCH2, WFS1, IGF2BP2, SLC30A8, JAZF1, HHEX, DGKB, CDKN2A, CDKN2B, KCNQ1, HNF1A, HNF1B MC4R, GIPR, HNF4A, MTNR1B, PARG6, ZBED3, SLC30A8, CDKAL1, GLIS3, GCKR, among others.[4][5][6][7]KCNJ11 (potassium inwardly rectifying channel, subfa Continue reading >>

Same Genetic Factor Causes Both Type 1 And Type 2 Diabetes

Same Genetic Factor Causes Both Type 1 And Type 2 Diabetes

Type 1 and type 2 diabetes may have the same underlying cause, namely “fragile” beta cells that are easily damaged by cellular stress. This was the conclusion of research by 29 researchers in Europe, Australia, and Canada led by Adrian Liston, who kindly sent me the full text of the paper. The research was published this month in the journal Nature Genetics. The traditional view of diabetes is that types 1 and 2 are quite different. Type 1 is an autoimmune disease in which the body’s own immune system destroys the beta cells, the cells that produce insulin, and the destruction is so great that patients must inject insulin. Type 2 is thought to occur because of insulin resistance. Insulin resistance means the body can still produce insulin, but cells don’t respond properly to it, so they are unable to overcome this resistance and may eventually die from “overwork.” The liver produces glucose when it thinks glucose is needed, and insulin is supposed to shut this process down when glucose levels are adequate. But insulin resistance in the liver means that it keeps pouring out glucose into the bloodstream even after meals when glucose levels are high. Because being overweight increases insulin resistance, obesity and rates of type 2 diabetes are associated, and some people call type 2 diabetes a “lifestyle disease” and blame patients with type 2 diabetes for “bringing it on themselves.” For this reason, some people want to change the names of the two diseases so it’s clear that they are different. But now it seems that the underlying cause of both diseases is the same: a genetic defect in the beta cells that makes them more susceptible to various kinds of stress. Without the fragile beta cells, people can tolerate insulin resistance by simply producing Continue reading >>

Type 1 Diabetes

Type 1 Diabetes

Print Overview Type 1 diabetes, once known as juvenile diabetes or insulin-dependent diabetes, is a chronic condition in which the pancreas produces little or no insulin. Insulin is a hormone needed to allow sugar (glucose) to enter cells to produce energy. Different factors, including genetics and some viruses, may contribute to type 1 diabetes. Although type 1 diabetes usually appears during childhood or adolescence, it can develop in adults. Despite active research, type 1 diabetes has no cure. Treatment focuses on managing blood sugar levels with insulin, diet and lifestyle to prevent complications. Symptoms Type 1 diabetes signs and symptoms can appear relatively suddenly and may include: Increased thirst Frequent urination Bed-wetting in children who previously didn't wet the bed during the night Extreme hunger Unintended weight loss Irritability and other mood changes Fatigue and weakness Blurred vision When to see a doctor Consult your doctor if you notice any of the above signs and symptoms in you or your child. Causes The exact cause of type 1 diabetes is unknown. Usually, the body's own immune system — which normally fights harmful bacteria and viruses — mistakenly destroys the insulin-producing (islet, or islets of Langerhans) cells in the pancreas. Other possible causes include: Genetics Exposure to viruses and other environmental factors The role of insulin Once a significant number of islet cells are destroyed, you'll produce little or no insulin. Insulin is a hormone that comes from a gland situated behind and below the stomach (pancreas). The pancreas secretes insulin into the bloodstream. Insulin circulates, allowing sugar to enter your cells. Insulin lowers the amount of sugar in your bloodstream. As your blood sugar level drops, so does the secre 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 >>

Nephrogenic Diabetes Insipidus

Nephrogenic Diabetes Insipidus

NORD gratefully acknowledges Jeff M. Sands, MD, Juha P. Kokko Professor of Medicine and Physiology, Renal Division Director, Executive Vice-Chair of Medicine, Emory University School of Medicine, for assistance in the preparation of this report. Synonyms of Nephrogenic Diabetes Insipidus acquired nephrogenic diabetes insipidus congenital nephrogenic diabetes insipidus hereditary nephrogenic diabetes insipidus NDI vasopressin-resistant diabetes insipidus General Discussion Summary Nephrogenic diabetes insipidus (NDI) is a rare kidney disorder that may be inherited or acquired. NDI is not related to the more common diabetes mellitus (sugar diabetes), in which the body does not produce or properly use insulin. NDI is a distinct disorder caused by complete or partial resistance of the kidneys to arginine vasopressin (AVP). Vasopressin is an antidiuretic hormone used by the kidney to manage water balance in the body. NDI causes chronic excessive thirst (polydipsia), excessive urine production (polyuria), and potentially dehydration. If left untreated, repeated episodes of severe dehydration may develop, eventually resulting in serious complications. Most cases of hereditary NDI are inherited as X-linked recessive disorders. Rare cases are inherited as an autosomal recessive or dominant disorder. Two different genes have been identified that cause hereditary NDI. NDI may also be acquired during life as a result of drug use (e.g., lithium therapy), kidney disease, obstruction of the tubes that carry urine from the kidneys to the bladder (ureters), and prolonged metabolic imbalances such as low levels of potassium in the blood (hypokalemia) or high levels of calcium in the blood (hypercalcemia). NDI may also be a temporary complication associated with pregnancy. Introduction Th Continue reading >>

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