Free 600 words essay on Genetic Disorders for school and college students.
Any change or mutation in the DNA sequence of a human gives rise to a genetic disorder. Classified into different types, the primary cause of a genetic disease is basically an abnormality that can range from minuscule to major. Some disorder of this kind is derived from parents while others can be caused by mutations in pre-existing genes or congenital. The most common types of diseases caused by DNA abnormality are Down syndrome, Cystic fibrosis, Huntington’s disease, Duchenne muscular dystrophy, Sickle cell anemia, Hemophilia, Thalassemia, Fragile X Syndrome etc. Some diseases are so complex that no proper diagnosis for complete cure has been discovered yet.
Mutations occur due to some error in DNA replication. This can even be caused by environmental factors such as smoking or radiation exposure. The human genome is basically a set of nucleic acid sequences that are encoded as DNA in 23 chromosome pairs in cell nuclei and also, in mitochondria. Human genome is capable of undergoing changes in the bases or chromosomes. In case of changes in DNA, the protein it codes for is also affected in some way and be incapable of carrying some function. Genetic disorders are of three types, single gene disorders, chromosomal abnormalities, and multifactorial disorders.
In case of a single gene disorder, there are mutations in DNA sequences of single genes, as a consequence of which the protein for gene code is either altered or missing. Common problems that arise as a result of this problem are Adenosine deaminase (ADA) deficiency, Alpha-1 Antitrypsin Deficiency, Cystic Fibrosis, Galactosemia, Huntington’s Disease, Maple Syrup Urine Disease (MSUD), Neurofibromatosis Type 1, Pachyonychia Congenita, Phenylketonuria, Severe Combined Immunodeficiency, Sickle Cell Disease, Smith-Lemli-Opitz Syndrome, etc. These disorders are inherited in recognizable patterns such as autosomal dominant, autosomal recessive, and X-linked. Dominant disorder occurs when an individual has one altered copy of the relevant gene and one healthy copy. Recessive disorder only occurs when an individual has two altered versions of the relevant gene. X-linked disorder reflect the presence of an altered gene on the X chromosome.
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Chromosomal abnormalities occur when the entire chromosomes, or large segments of them, are missing, duplicated, or otherwise altered. Cri-du-Chat Syndrome, Down Syndrome, 47, XXY (Klinefelter syndrome), Turner Syndrome, Williams Syndrome, etc. Chromosomes are carriers of genetic materials. The diseases may also occur due to chromosomal translocation in which portions of two chromosomes are exchanged. For example, Down’s syndrome is a chromosome disorder resulting from an extra chromosome 21.
Multifactorial disorders involve variations in multiple genes, often coupled with environmental causes. Some common demonstrable examples can be Alzheimer’s Disease, Breast Ovarian Cancer, Colon Cancer, and Hypothyroidism.
Another form of genetic disorder is mitochondrial inheritance which is caused by mutations in the non-nuclear DNA of mitochondria. Mitochondria are organelles, or parts of a eukaryote cell that make most of the cell’s supply of adenosine triphosphate (ATP), a molecule that cells use as a source of energy. Each mitochondrion may contain 5 to 10 circular pieces of DNA. Examples of mitochondrial diseases include Leber’s hereditary optic atrophy, myoclonic epilepsy, and a form of dementia named as mitochondrial encephalopathy, lactic acidosis and stroke-like episodes (MELAS).
The process of diagnosis of genetic disorders in extremely complicated. Scientific discoveries in the field of medical science are witnessing growth at a lightning pace. The Human Genome Project is an international, collaborative research program whose goal was the complete mapping and understanding of all the genes of human beings. This is expected to understand human’s susceptibility to diseases and help find treatments.