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Most Severe Genetic Disorders 

Introduction:

A genetic disorder is due to changes in the human genome or DNA( DNA is a molecule present in human cell which stores information of structure and functions of whole body) DNA is made up of multiple genes. Mutation can be in one gene called as monogenic disorder, or can be in multiple genes called as multifactorial inheritance disorder, or due to gene mutations combined with environmental factors , or changes in whole chromosomes due to damage to it.

Types of genetic disorders:

Monogenetic disorders:

This disorder is caused by a change or mutations in one or two genes. It is again divided in to ''dominant'' and ''recessive''. Example of monogenetic disorders are sickle cell disease, cystic fibrosis, poly-cystic kidney disease. Dominant disease is due to presence of disease gene on one of the two inherited parental chromosomes, so there is 50 percent of chances that the child inherit disease. Example of dominant diseases are huntington's disease .If inherited parental chromosomes both have disease gene so their will be 25 percent chance of child inherit the disease. Example of recessive disease include cystic fibrosis.

Multi-factorial inheritance disorders:

This type of genetic disorders are caused when there is more than one gene involved in the alterations of acting together with environmental factors. The most common multifactorial disorder is type2 diabetes caused in combination of disorder plus environmental factor obesity.

Chromosomal disorder:

This disorders are caused by the deficiency of the genes or structural changes in the chromosomes. Examples of chromosomal disorders are down syndrome, prader-willi syndrome. Chromosomal abnormalities can be numerical abnormalities, when chromosome is missing known as monosomy or has more than two chromosomes known as trisomy as seen in down syndrome, who has three copies of chromosome 21 rather than two copies. Structural abnormalities are other type which can be deletions ,duplication's,trans-locations,inversions rings.

Genetic disorders In humans:

Achondroplasia:

It is a bone growth disorder with disproportionate short stature. It occurs due to alterations in gene FGFR3. It is inherited from parent who has achondroplasia, but most of the cases are not inherited, if inherited it will be as autosomal dominant type. Symptoms include short height (average height of achondroplasia adult is 4 feet 4 inches), short arms and legs, short fingers, a large head with prominent forehead, weak muscle, breathing problems.

Down syndrome:

Down syndrome is a chromosomal condition that is associated with intellectual disability, people with down syndrome has a characteristic facial appearance and low muscle tone in infancy. People with down syndrome may born with a variety of health concerns including heart defects and digestive defects. They also have increased risk of developing celiac disease and vision problems. Down syndrome is caused by having three copies of chromosome 21 which normally has to be two copies. Most of the cases of down syndrome is not inherited, but results because of some abnormalities during the reproductive cell formation.

Thalassemia:

Thalassemia is a inherited blood disorder that occurs when the body does not make enough hemoglobin as a result the RBC doesn't function properly and which leads to decreased oxygen supply to the cells. There are two main types of thalassemia, alpha thalassemia and beta thalassemia. People with thalassemia suffer from anaemia. Other symptoms include bone deformities in the face, growth failure, shortness of breath and yellow skin. It is inherited from diseased parents to children. Disease severity varies from mild to severe. In severe disease conditions bone marrow transplantation's and regular blood transfusions are done. In moderate disease conditions blood transfusion is made once in a while.

Hemophilia:

Hemophilia is a bleeding disorder that slows blood clotting process. Symptoms of this disease include prolonged bleeding after injury or surgery. Their are two types of hemophilia, hemophilia A and hemophilia B, acquired hemophilia. Both Hemophilia A and B have similar signs and symptoms but differentiated with mutations in different genes, Acquired hemophilia is not inherited. Hemophilia A is due to deficiency of Blood clotting factor VIII , Hemophilia B is due to deficiency of blood clotting factor IX

Duchenne:

Duchenne is a rapidly progressive form of muscular dystrophy (degeneration of muscle) primarily effects skeletal muscle. On set of disease is seen in early childhood and worsens with age. It effects mainly boys. It is caused by mutation in gene called DMD gene. Patients with duchenne lack the dystrophin protein in the muscle. Their is a progressive loss of muscle function. It is inherited as X linked recessive fashion. This disease is inherited from parents to children. It is the most degenerative disorder which effects patient's life span.