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 >>
Genetic Risk Factors For Type 1 Diabetes
Summary Type 1 diabetes is diagnosed at the end of a prodrome of β-cell autoimmunity. The disease is most likely triggered at an early age by autoantibodies primarily directed against insulin or glutamic acid decarboxylase, or both, but rarely against islet antigen-2. After the initial appearance of one of these autoantibody biomarkers, a second, third, or fourth autoantibody against either islet antigen-2 or the ZnT8 transporter might also appear. The larger the number of β-cell autoantibody types, the greater the risk of rapid progression to clinical onset of diabetes. This association does not necessarily mean that the β-cell autoantibodies are pathogenic, but rather that they represent reproducible biomarkers of the pathogenesis. The primary risk factor for β-cell autoimmunity is genetic, mainly occurring in individuals with either HLA-DR3-DQ2 or HLA-DR4-DQ8 haplotypes, or both, but a trigger from the environment is generally needed. The pathogenesis can be divided into three stages: 1, appearance of β-cell autoimmunity, normoglycaemia, and no symptoms; 2, β-cell autoimmunity, dysglycaemia, and no symptoms; and 3, β-cell autoimmunity, dysglycaemia, and symptoms of diabetes. The genetic association with each one of the three stages can differ. Type 1 diabetes could serve as a disease model for organ-specific autoimmune disorders such as coeliac disease, thyroiditis, and Addison's disease, which show similar early markers of a prolonged disease process before clinical diagnosis. Continue reading >>
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 >>
Is Type 2 Diabetes Caused By Genetics?
Diabetes is a complex condition. Several factors must come together for you to develop type 2 diabetes. For example, obesity and a sedentary lifestyle play a role. Genetics can also influence whether you’ll get this disease. If you’ve been diagnosed with type 2 diabetes, there’s a good chance that you’re not the first person with diabetes in your family. According to the American Diabetes Association, your risk of developing type 2 diabetes is: 1 in 7 if one of your parents was diagnosed before the age of 50 1 in 13 if one of your parents was diagnosed after the age of 50 1 in 2, or 50 percent, if both your parents have diabetes Several gene mutations have been linked to the development of type 2 diabetes. These gene mutations can interact with the environment and each other to further increase your risk. Type 2 diabetes is caused by both genetic and environmental factors. Scientists have linked several gene mutations to a higher diabetes risk. Not everyone who carries a mutation will get diabetes. But many people with diabetes do have one or more of these mutations. It can be difficult to separate genetic risk from environmental risk. The latter is often influenced by your family members. For example, parents with healthy eating habits are likely to pass them on to the next generation. On the other hand, genetics plays a big part in determining weight. Sometimes behaviors can’t take all the blame. Studies of twins suggest that type 2 diabetes might be linked to genetics. These studies were complicated by the environmental influences that also affect type 2 diabetes risk. To date, numerous mutations have been shown to affect type 2 diabetes risk. The contribution of each gene is generally small. However, each additional mutation you have seems to increase your Continue reading >>
Type 1 Diabetes
Overview Diabetes is a lifelong condition that causes a person's blood sugar (glucose) level to become too high. The hormone insulin, produced by the pancreas, is responsible for controlling the amount of glucose in the blood. There are two main types of diabetes: type 1 – where the pancreas doesn't produce any insulin type 2 – where the pancreas doesn't produce enough insulin or the body's cells don't react to insulin These pages are about type 1 diabetes. Other types of diabetes are covered separately (read about type 2 diabetes, and gestational diabetes, which affects some women during pregnancy). Symptoms of diabetes Typical symptoms of type 1 diabetes are: feeling very thirsty passing urine more often than usual, particularly at night feeling very tired weight loss and loss of muscle bulk The symptoms of type 1 diabetes usually develop very quickly in young people (over a few days or weeks). In adults, the symptoms often take longer to develop (a few months). Read more about the symptoms of type 1 diabetes. These symptoms occur because the lack of insulin means that glucose stays in the blood and isn’t used as fuel for energy. Your body tries to reduce blood glucose levels by getting rid of the excess glucose in your urine. It's very important for diabetes to be diagnosed as soon as possible, because it will get progressively worse if left untreated. Find your local GP service Read about how type 1 diabetes is diagnosed. Causes of type 1 diabetes Type 1 diabetes is an autoimmune condition, which means your immune system attacks healthy body tissue by mistake. In this case, it attacks the cells in your pancreas. Your damaged pancreas is then unable to produce insulin. So, glucose cannot be moved out of your bloodstream and into your cells. Type 1 diabetes is o Continue reading >>
Is Diabetes Hereditary?
Diabetes loves families! It's true that genetics play a role in your diabetes risk. If you have a parent or sibling with diabetes, especially type 2 diabetes, your odds are significantly higher. For example, if one twin has type 2 diabetes, the other has a 3 in 4 chance of developing it, too. However, the American Diabetes Association notes that heredity isn't destiny. While you may be genetically predisposed to diabetes, healthy habits, such as watching your weight and exercising, can delay or even prevent diabetes. There is a genetic component in both Type 1 and Type 2 Diabetes that may make an individual more susceptible to developing the disease. In Type 2 Diabetes, this explains why some obese individuals develop Diabetes and some remain healthy. Many different genes have been identified which may contribute to Diabetes when coupled with certain environmental triggers throughout the lifespan. In Type 2 Diabetes, most of the genes which have been identified are associated with dysfunction of the Beta cells, and to a lesser extent genes associated with insulin sensitivity and obesity. The Beta cells are responsible for insulin production in the pancreas. Many susceptibility genes have also been identified for Type 1 Diabetes, but the most studied is the IDDM1 gene on the HLA region on chromosome 6p21. Individuals with certain variants of this gene are more likely to develop Type 1 Diabetes. Environmental exposures, such as viral and bacterial infections, Vitamin D deficiency or early introduction to cow's milk, have been indicated in triggering these genes leading to the development of Type 1 Diabetes. There is also a higher risk of developing Type 1 Diabetes if a parent or sibling has the disease. Unlike some traits, diabetes does not seem to be inherited in a simpl Continue reading >>
What Causes Type 1 Diabetes?
Causes of type 1 diabetes If you have just been diagnosed with type 1 diabetes you are probably wondering, 'why me?' It is important to know it is not your fault that you have type 1 diabetes – it is not caused by poor diet or an unhealthy lifestyle. In fact, it isn’t caused by anything that you did or didn’t do, and there was nothing you could have done to prevent it. Because the precise causes of type 1 diabetes are not known and there is a much greater awareness of type 2 diabetes, many myths about type 1 diabetes are in circulation. There has been a lot of research into what causes type 1 diabetes, but so far there are no clear answers. Type 1 is an autoimmune condition. An autoimmune condition is when your immune system, which normally keeps your body safe against disease, attacks itself instead. Other examples of autoimmune conditions include multiple sclerosis (MS) and rheumatoid arthritis. In type 1 diabetes, the immune system attacks and destroys your insulin-producing beta cells. Certain genes put people at a greater risk for developing type 1 diabetes, but are not the only factors involved. While there are no proven environmental triggers, researchers are looking for possible culprits, such as viral infections and particular molecules within our environment and foods. Is type 1 diabetes hereditary? We are also unsure about whether type 1 diabetes is hereditary or not. While 90 per cent of people who develop type 1 diabetes have no relative with the condition, genetic factors can pre-dispose people to developing type 1 diabetes. Certain gene markers are associated with type 1 diabetes risk. A child born with these will have the same risk of developing type 1 diabetes as a child with siblings with type 1 diabetes. However, having the marker alone is not e Continue reading >>
Type 2 Diabetes
Type 2 diabetes is a progressive condition in which the body becomes resistant to the normal effects of insulin and/or gradually loses the capacity to produce enough insulin in the pancreas. We do not know what causes type 2 diabetes. Type 2 diabetes is associated with modifiable lifestyle risk factors. Type 2 diabetes also has strong genetic and family related risk factors. Type 2 diabetes: Is diagnosed when the pancreas does not produce enough insulin (reduced insulin production) and/or the insulin does not work effectively and/or the cells of the body do not respond to insulin effectively (known as insulin resistance) Represents 85–90 per cent of all cases of diabetes Usually develops in adults over the age of 45 years but is increasingly occurring in younger age groups including children, adolescents and young adults Is more likely in people with a family history of type 2 diabetes or from particular ethnic backgrounds For some the first sign may be a complication of diabetes such as a heart attack, vision problems or a foot ulcer Is managed with a combination of regular physical activity, healthy eating and weight reduction. As type 2 diabetes is often progressive, most people will need oral medications and/or insulin injections in addition to lifestyle changes over time. Type 2 diabetes develops over a long period of time (years). During this period of time insulin resistance starts, this is where the insulin is increasingly ineffective at managing the blood glucose levels. As a result of this insulin resistance, the pancreas responds by producing greater and greater amounts of insulin, to try and achieve some degree of management of the blood glucose levels. As insulin overproduction occurs over a very long period of time, the insulin producing cells in the pan Continue reading >>
Diabetes In The Family: Is It Inherited?
I’m asking this on behalf of a friend whose grandfather and father have diabetes. Is it more likely that my friend will get it too? Is diabetes fatal? Diabetes occurs in two forms; type 1 diabetes (insulin-dependent diabetes), which occurs in young people and is the more severe form, requiring insulin injections type 2 diabetes (non-insulin dependent diabetes), which is milder and occurs in older people and is usually controlled with diet and tablets. The details of whether diabetes can be inherited, and how this occurs, are not clear. About 10 per cent of people getting the more severe Type 1 diabetes have a close relative with this type of diabetes. That is not the same as saying that 10 per cent of people with affected relatives will get diabetes, but there is an unpredictable association. Type 2 diabetes also has a tendency to occur in families, but this is also not very strong and not predictable. In your friend’s case, if grandfather and father are affected, they probably have the milder Type 2 form of diabetes, so your friend has little risk of developing diabetes at a young age. It may be there is an increased risk of him developing diabetes in later life, but it would be the milder Type 2 form. I am a little confused that you say, ‘he takes pills and does a blood sugar test’. If you are referring to your friend then this probably means he has the mild form of diabetes already, and is probably an older person. You ask if you can get very ill with diabetes and die. Diabetes is a serious condition, but these days if patients follow their diet and take their pills or insulin treatment regularly, and keep their blood sugar within certain limits, they rarely get seriously ill and can live a long and active life. That is not to say there are no dangers with di Continue reading >>
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 >>
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 >>
Type 2 Diabetes
Type 2 diabetes is a disorder characterized by abnormally high blood sugar levels. In this form of diabetes, the body stops using and making insulin properly. Insulin is a hormone produced in the pancreas that helps regulate blood sugar levels. Specifically, insulin controls how much glucose (a type of sugar) is passed from the blood into cells, where it is used as an energy source. When blood sugar levels are high (such as after a meal), the pancreas releases insulin to move the excess glucose into cells, which reduces the amount of glucose in the blood. Most people who develop type 2 diabetes first have insulin resistance, a condition in which the body's cells use insulin less efficiently than normal. As insulin resistance develops, more and more insulin is needed to keep blood sugar levels in the normal range. To keep up with the increasing need, insulin-producing cells in the pancreas (called beta cells) make larger amounts of insulin. Over time, the beta cells become less able to respond to blood sugar changes, leading to an insulin shortage that prevents the body from reducing blood sugar levels effectively. Most people have some insulin resistance as they age, but inadequate exercise and excessive weight gain make it worse, greatly increasing the likelihood of developing type 2 diabetes. Type 2 diabetes can occur at any age, but it most commonly begins in middle age or later. Signs and symptoms develop slowly over years. They include frequent urination (polyuria), excessive thirst (polydipsia), fatigue, blurred vision, tingling or loss of feeling in the hands and feet (diabetic neuropathy), sores that do not heal well, and weight loss. If blood sugar levels are not controlled through medication or diet, type 2 diabetes can cause long-lasting (chronic) health prob Continue reading >>
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 >>
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 >>
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- Women in India with Gestational Diabetes Mellitus Strategy (WINGS): Methodology and development of model of care for gestational diabetes mellitus (WINGS 4)
- Postprandial Blood Glucose Is a Stronger Predictor of Cardiovascular Events Than Fasting Blood Glucose in Type 2 Diabetes Mellitus, Particularly in Women: Lessons from the San Luigi Gonzaga Diabetes Study
Type 2 Diabetes Is More Common Than Type 1 Diabetes.
Whereas type 1 diabetes is characterized by the onset in young persons (average age at diagnosis = 14), type 2 diabetes usually develops in middle age or later. This tendency to develop later in life has given rise to the term "adult onset diabetes," although the prevalence of type 2 diabetes in younger people is rising, making this term somewhat inaccurate and outdated. The typical type 2 diabetes patient is overweight ,although there are exceptions. In contrast to type 1 diabetes, symptoms often have a more gradual onset. Type 2 diabetes is associated with insulin resistance rather than the lack of insulin, as seen in type 1 diabetes. This often is obtained as a hereditary tendency from one's parents. Insulin levels in these patients are usually normal or higher than average but the body's cells are rather sluggish to respond to it. This lack of insulin activity results in higher than normal blood glucose levels. Incidence of Type 2 Diabetes Type 2 diabetes is the most common type of diabetes. This disease exists in all populations, but prevalence varies greatly, ie, 1% in Japan, and greater than 40% in the Pima Indians of Arizona. In Caucasians, the figure is somewhere between 1-2% of the entire population. The high incidence of type 2 diabetes in certain groups such as the Pima Indians appears to be a relatively recent development that followed a change in the type of food intake (from relatively little food to plenty of food). With this came the development of obesity within their culture which results in diabetes developing in those that are genetically predisposed. This "urbanization phenomenon" has been most carefully studied in non-white populations, but is probably ethnically and racially nonspecific. In other words, obesity tends to promote diabetes in those Continue reading >>
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- Advice to walk after meals is more effective for lowering postprandial glycaemia in type 2 diabetes mellitus than advice that does not specify timing: a randomised crossover study