Every morning sunrise will look pleasant only when we are capable of enjoying it. Enjoyment is always complimented with health. Disease is that disturbance caused to the normal functioning of the body disturbing the health. But is really disease that bad? Disease is that state of the body which is fighting the interfering substance causing it. For example when we have prolonged common cold the obvious symptoms during the course are fever, headache, running nose. Since the body is fighting against the infection causing substance these reactions are exhibited so as to eliminate the pathogen by discharge of mucous and the immune response triggered is responsible for the raise in body temperature. Now isn't that sounding obvious that we can say disease is a state developed to bring back the normal health in an individual?
A genetic disorder is a disease that is caused by an abnormality in an individual's DNA. DNA is the genetic material present in every single cell of our body and dictates life! A disturbance in this genetic material will result in the abnormal function of the body leading to a disorder and thus a genetic disease. Mutations are the source of variation, but at times when mutation occurs it will result in life threatening abnormality. Mutation is that permanent change happening in gene DNA which can not only cause the disease but also can be transferred to the next generation!!! Our genetic material, DNA is a stretch of nucleotides having a specific sequence and is interspersed with specific coding sequence namely the gene. If there is a change in the coding sequence by either replacement or addition or deletion of nucleotides the sequence becomes non sense and hence the protein produced will be a faulty one. The central dogma of life is DNA needs to be conserved and hence replication happens to synthesize an identical DNA, Transcription is a process where in the DNA passes on the genetic information to mRNA which is processed and finally translated into a functional protein. When Central dogma and mutation are tagged with each other it results in alterations in the process and resulting in disease.
Mutation occurs at various levels in the genome, which can be broadly categorized as Single gene disorders, Chromosomal abnormalities, Multifactorial Disorders. Single gene disorder is best described when a disorder caused by alteration in one particular gene resulting in an altered or missing protein and some of the examples include Cystic fibrosis, Sickle cell disease, Huntington's disease, Severe combined immunodeficiency. A deletion of 3 base pairs in the gene CFTR on chromosome 7 causes the disease namely cystic fibrosis. A deletion accompanies the missing protein leading to absence of a particular amino acid, due to which there is an abnormality in the structure of the protein. This will tender the protein abnormal and hence the protein fails to function normally which is supposedly facilitate to move salt in and out of the cell.A thick Mucus accumulation will result in clogging of the air pathways in the lungs and also have impact on the digestive system. Chromosomal abnormalities results due to deletion , duplication or changes in large segment of chromosomes. Chromosome is the organized structure of DNA and proteins in the cell, which is actively involved in phenomenon such as transcription, recombination and cell division. Well known chromosomal abnormalities include Turners syndrome, Cri-du-chat syndrome, Klinefelters syndrome and others. In Cri-du-chat syndrome there is a deletion in the short arm of chromosome 5 because of which many genes are affected and the larynx development in these individuals are abnormal leading to a cat cry like noise when they cry later leading to many more abnormalities. It is not always true that a single gene code a complete functional protein ,there are several proteins formed by the interaction of multiple gene products. When there is a mutation in multiple genes influenced by external factors such as age and environment it will result in Multifactorial Disorders namely Colon cancer, breast cancer, Alzheimer disease, diabetes, obesity and others. Obesity is also result of interplay of genes which determine the metabolic rate and body mass index. There are several genes involved as the polymorphic alleles of gene FTO and environment which influence obesity. Since the interaction is huge research is still being carried out to get the perfect schematic representation of the cause.
Biotechnology has aided us tools to diagnose genetic disease in the early stages. The tests examine directly the DNA molecule or biochemical analysis of proteins are carried out to test the gene product, staining pattern of the chromosomes also show valuable results to identify disease. The result is based on the Comparison of normal report obtained from the mass population and the suspected patient. Diagnosis has now started at the prenatal level to eliminate the chance of a defective child being borne. Diagnosis is always preceded by therapy and gene therapy is one of the fascinating areas in the field where the defective gene is targeted to eliminate the risk at the base level.
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