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 >>
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 >>
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 >>
Is Type 2 Diabetes Genetic?
As others have answered, inherited genes affect the risk of type 2 diabetes, as does one’s environment, personal habits, and simple aging. But as or more important than the genes you inherit are EPIgenetic changes, which can be inherited from parents or acquired in the womb and early infancy. It’s not just the alleles (forms of each gene) that one inherits, it’s a which genes/alleles are switched on or off in various parts of you body as you developed in your mother’s womb. Babies conceived during times of famine switch on hundreds or thousands of genes in anticipation of having to survive after birth in an environment of extreme scarcity. If these babies then grow up in a world of abundant food and little need to exercise, those switched-on genes become dangerously dysfunctional, leading to obesity, diabetes and other problems.* These switching patterns can be themselves inherited, almost like true genetic variations, for at least a couple of generations. Epigenetics probably explains why 50% or persons over age 50 have type 2 diabetes in, for example, Middle Eastern countries that were desperately poor before the discovery of oil. It also explains why diabetes and pre-diabetes rates are higher among persons born during the Great Leap Forward famine in China, and during the famine in the Netherlands during World War II. *Malnourishment causes other health problems directly, as well, such has high blood pressure resulting from the growth of too few arteries during gestation, pancreases that have too few insulin-producing cells to control blood sugar, and underdeveloped neural and mental capacity. Societies that do not feed and support mothers and children pay a huge price in underdevelopment and downstream social and health care problems. 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 >>
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 >>
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 >>
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 >>
How Can We Prevent Genetic Diabetes?
Type I diabetes, we can’t yet. We have to look for more specific genetic markers to select a group of children at a very high risk of developing diabetes and do a trial treating them with immune modulating drug to see whether we could really prevent type I diabetes from developing in them. At present the markers are no specific enough, around 15% of those having certain genetic markers will develop a type I diabetes, so not good enough a discriminator to use in selecting whom to treat preventatively. See Risk Factors and Primary Prevention Trials for Type 1 Diabetes For type 2 diabetes, in at least three large trials it has been shown that in people having pre-diabetes losing weight and exercising can prevent, at least delay, the development of type 2 diabetes for a time: it also showed a significant lower risk for mortality in those who followed the lifestyle modifications 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 >>
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 >>
The Genetic Architecture Of Type 1 Diabetes
Type 1 diabetes (T1D) is classically characterised by the clinical need for insulin, the presence of disease-associated serum autoantibodies, and an onset in childhood. The disease, as with other autoimmune diseases, is due to the interaction of genetic and non-genetic effects, which induce a destructive process damaging insulin-secreting cells. In this review, we focus on the nature of this interaction, and how our understanding of that gene–environment interaction has changed our understanding of the nature of the disease. We discuss the early onset of the disease, the development of distinct immunogenotypes, and the declining heritability with increasing age at diagnosis. Whilst Human Leukocyte Antigens (HLA) have a major role in causing T1D, we note that some of these HLA genes have a protective role, especially in children, whilst other non-HLA genes are also important. In adult-onset T1D, the disease is often not insulin-dependent at diagnosis, and has a dissimilar immunogenotype with reduced genetic predisposition. Finally, we discuss the putative nature of the non-genetic factors and how they might interact with genetic susceptibility, including preliminary studies of the epigenome associated with T1D. View Full-Text Figure 1 This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. (CC BY 4.0). Continue reading >>
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 >>
Genetics Of Type 1 Diabetes
In western populations, each child has a 0.3–0.4% risk of developing diabetes by the age of 20 years; the risk increases 15-fold in siblings of an affected child. Lifetime risks are more difficult to estimate, but may be about twice as high as this. Some 50% of the genetic risk of type 1 diabetes is conferred by genes in the human leucocyte antigen (HLA) region on chromosome 6. The HLA Class II susceptibility haplotypes DR4-DQ8 and DR3-DQ2 are present in 90% of children with type 1 diabetes, whereas DR15-DQ6 is associated with protection. High risk HLA haplotypes in a child with no family history of disease confer a risk similar to that of having an affected sibling (5–6%), and this risk rises rapidly if one or both haplotypes are shared with the affected sibling. The promoter region of the insulin gene on chromosome 11 contributes about 10% of genetic susceptibility. Many other genes (currently more than 40) make a minor contribution to type 1 diabetes, and several are of particular interest because they influence different aspects of immune function. Their ability to predict diabetes is, however, limited. Empirical risks By the age of 20 years, type 1 diabetes will have affected some 0.3–0.4% of children in the background population in western countries, and about 6% of siblings of childhood onset cases, giving a ratio (λs) of 15. Early-onset diabetes carries a higher familial risk, and affected fathers are more likely to transmit type 1 diabetes to their offspring than affected mothers, with risks being 6–9% and 1–3%, respectively. These estimates represent the risk of diabetes development by young adult life, not the lifetime risk. The latter is not well established, and may be as high as 1% in the background population and 15% in siblings. Siblings wh Continue reading >>
Is Diabetes Genetically Transmitted Or Through Eating Unhealthy?
You have to be specific: How type 1 diabetes develops: Type 1 diabetes is an autoimmune disease, which means it results from the immune system mistakenly attacking parts of the body. In the case of type 1 diabetes, the immune system incorrectly targets insulin-producing beta cells in the pancreas. Nobody knows why this occurs, or how to stop it. The immune systems of people with type 1 diabetes continue to attack beta cells until the pancreas is incapable of producing insulin. People with type 1 diabetes need to inject themselves with insulin to compensate for the death of their beta cells. Everyone with type 1 diabetes is insulin-dependent. How type 2 diabetes develops: Type 2 diabetes is different. The autoimmune systems of people with type 2 diabetes don't attack beta cells. Instead, type 2 diabetes is characterised by the body losing its ability to respond to insulin. This is known as insulin resistance. The body compensates for the ineffectiveness of its insulin by producing more, but it can't always produce enough. Over time, the strain placed on the beta cells by this level of insulin production can destroy them, diminishing insulin production. Type 2 diabetes is linked to obesity; sugars, and particularly the problem of added sugars, have been linked with increased risks of the following health problems: Weight gain and obesity Type 2 diabetes Tooth decay Heart disease Having said that, the genetic risk is as follows. Type 1 diabetes and genetics - average risks: Mother with diabetes increases risk of diabetes by 2% Father with diabetes increases risk of diabetes by 8% Both parents with diabetes increases risk by 30% Brother or sister with diabetes increases risk by 10% Non-identical twin with diabetes increases risk by 15% Identical twin with diabetes increases Continue reading >>