Genetics is the mystery behind many non-communicable diseases today. In some cases, it is possible to analyze this using family history of genetic disorders. But this is not practical when a disease is caused by mutations. When there’s a risk for a certain disease genetically, it is better to control other factors influencing the disease. Prenatal diagnosis is used to diagnose genetic diseases at pregnancy.
Diabetes mellitus is a non-communicable disease which is widely found throughout the world. It is a multifactorial inherited disease. Environmental factors play a major role in the expression of these genes. Diabetes is classified into two types; type I which is insulin dependent Diabetes and type II which is non-insulin dependent. Onset of insulin dependent diabetes is at early childhood and type II diabetes is seen at 30-40 years.
Diabetes mellitus I is caused by autoimmune destruction of islet β cells in pancreas. This destruction of islet β cells causes insulin deficiency and deregulation of anabolism and catabolism. More than 13 different susceptible gene loci have been identified. This locus behaves as a haplotype. Later it was discovered that β polypeptide of DQ II protein which is a dimer is a part of HLA. This protein has aspartic acid in 57th position in protective or neutral alleles, If it’s replaced with a neutral amino acid like serine, alanine; they are susceptible for DM type I. Amino acid in the 57th position is important for the specificity of antigen binding. Another cause of DM type I is variable number of tandem repeats (VNTR) in the promoter region of insulin encoding gene. If VNTR’s increase, these individuals are more susceptible to type I Diabetes. Patients with DM type I has a reduced tolerance for glucose level, hyperglycemia and ketoacidosis. Type II Diabetes is the most common which is characterized by relative insulin deficiency and resistance. Hyperglycemia and hyperinsulinemia are symptoms of Diabetes type II. Persistent hyperglycemia desensitize the islet β cells such that less insulin is released for a given glucose level. Elevated basal insulin levels down regulate the insulin receptors thereby increase in insulin resistance. Glucagon is unopposed and it’s secretion increases worsening hyperglycemia. An allele at short tandem repeat variations in the intron for a transcription factor TCF7L2 is associated with type II Diabetes. It encodes a transcription factor involved in the expression of hormone glucagon which raises blood glucose concentrations.
Rheumatoid arthritis is an autoimmune disease that causes chronic inflammation of joints and also can cause inflammation of the tissues around the joints. It is a systemic illness that can last for years. It causes joint destruction and functional disability. It is commonly seen in women. Lymphocytes are activated and chemical messengers like cytokines are expressed in inflammated areas producing symptoms like swelling, stiffness of joints, tendons etc.
X linked agammaglobulinemia is a genetic disorder. This is also called as X linked hypagammaglobulinemia, Brufon syndrome. It is more commonly seen among males. Individuals with this genetic defect do not produce mature B cells, which are responsible for the production of antibodies. People with untreated XLA are prone to develop serious and even fatal infections. XLA is caused due to a mutation in X chromosome of a single gene known as Bruton’s tyrosine kinase (Btk) gene. This mutation leads to a severe block in B cell development and a reduced peripheral Ig G immunoglobulin antibody production in the serum. Btk gene is responsible for mediating B cell development and maturation, through a signaling effect on B cell receptor. It is primarily an immune deficiency disorder.
Sickle cell anemia is an autosomal recessive disorder. It is caused due to a point mutation in β polypeptide gene. Diseased people are homozygous for the sickle cell allele. Heterozygotes for sickle cell allele who are healthy but carriers; are called as sickle cell trait whereas homozygous diseased are called as sickle cell anemics. Red blood cells of diseased individuals have a characteristic property of undergoing reversible alterations in shape when subjected to changes in the partial pressure of Oxygen. RBC’s become sickle shaped instead of flat discs. In the point mutation which is a substitution of the gene encoding for β polypeptide, the 6th amino acid, Glutamic acid is substituted with Valine.
Apart from these diseases; Phenylketonuria, graft versus host disease, Neurofibromatosis, Polycystic kidney disease are among genetic factorial diseases. Environmental factors such as age, nutrition, other diseases also affect for these diseases.
Diabetes mellitus is a non-communicable disease which is widely found throughout the world. It is a multifactorial inherited disease. Environmental factors play a major role in the expression of these genes. Diabetes is classified into two types; type I which is insulin dependent Diabetes and type II which is non-insulin dependent. Onset of insulin dependent diabetes is at early childhood and type II diabetes is seen at 30-40 years.
Diabetes mellitus I is caused by autoimmune destruction of islet β cells in pancreas. This destruction of islet β cells causes insulin deficiency and deregulation of anabolism and catabolism. More than 13 different susceptible gene loci have been identified. This locus behaves as a haplotype. Later it was discovered that β polypeptide of DQ II protein which is a dimer is a part of HLA. This protein has aspartic acid in 57th position in protective or neutral alleles, If it’s replaced with a neutral amino acid like serine, alanine; they are susceptible for DM type I. Amino acid in the 57th position is important for the specificity of antigen binding. Another cause of DM type I is variable number of tandem repeats (VNTR) in the promoter region of insulin encoding gene. If VNTR’s increase, these individuals are more susceptible to type I Diabetes. Patients with DM type I has a reduced tolerance for glucose level, hyperglycemia and ketoacidosis. Type II Diabetes is the most common which is characterized by relative insulin deficiency and resistance. Hyperglycemia and hyperinsulinemia are symptoms of Diabetes type II. Persistent hyperglycemia desensitize the islet β cells such that less insulin is released for a given glucose level. Elevated basal insulin levels down regulate the insulin receptors thereby increase in insulin resistance. Glucagon is unopposed and it’s secretion increases worsening hyperglycemia. An allele at short tandem repeat variations in the intron for a transcription factor TCF7L2 is associated with type II Diabetes. It encodes a transcription factor involved in the expression of hormone glucagon which raises blood glucose concentrations.
Rheumatoid arthritis is an autoimmune disease that causes chronic inflammation of joints and also can cause inflammation of the tissues around the joints. It is a systemic illness that can last for years. It causes joint destruction and functional disability. It is commonly seen in women. Lymphocytes are activated and chemical messengers like cytokines are expressed in inflammated areas producing symptoms like swelling, stiffness of joints, tendons etc.
X linked agammaglobulinemia is a genetic disorder. This is also called as X linked hypagammaglobulinemia, Brufon syndrome. It is more commonly seen among males. Individuals with this genetic defect do not produce mature B cells, which are responsible for the production of antibodies. People with untreated XLA are prone to develop serious and even fatal infections. XLA is caused due to a mutation in X chromosome of a single gene known as Bruton’s tyrosine kinase (Btk) gene. This mutation leads to a severe block in B cell development and a reduced peripheral Ig G immunoglobulin antibody production in the serum. Btk gene is responsible for mediating B cell development and maturation, through a signaling effect on B cell receptor. It is primarily an immune deficiency disorder.
Sickle cell anemia is an autosomal recessive disorder. It is caused due to a point mutation in β polypeptide gene. Diseased people are homozygous for the sickle cell allele. Heterozygotes for sickle cell allele who are healthy but carriers; are called as sickle cell trait whereas homozygous diseased are called as sickle cell anemics. Red blood cells of diseased individuals have a characteristic property of undergoing reversible alterations in shape when subjected to changes in the partial pressure of Oxygen. RBC’s become sickle shaped instead of flat discs. In the point mutation which is a substitution of the gene encoding for β polypeptide, the 6th amino acid, Glutamic acid is substituted with Valine.
Apart from these diseases; Phenylketonuria, graft versus host disease, Neurofibromatosis, Polycystic kidney disease are among genetic factorial diseases. Environmental factors such as age, nutrition, other diseases also affect for these diseases.
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