Analysis of Family Inherited Diseases - Case Study Example

Analysis of family inherited diseases Anna Fihar I was analyzing my genetic branch, starting with my grandmother on mother`s line. The main purpose of my observation was to identify predisposing to inherited diseases. My grandmother has a cystic fibrosis, but my mother, hasn`t any symptoms of this disease. My father is also healthy. First of all I sorted out all information about this inherited disease. Cystic fibrosis is an inherited disease that characterized by damage of mucus production, mostly in the lungs, pancreas and intestine. Mucus is the slimy body fluid that secreted by mucous membrane and covered internal organs. Normal production of mucus is really important, because it protects epithelial cells, thin layer that line the internal surface of respiratory, gastrointestinal, reproductive systems and other organs. Cystic fibrosis cause production of anomaly thick and sticky mucus that can block the airways and lead to defects in the lung and problems with breathing: wheezing, chronic coughing, inflammation. Stacked thick mucus with bacteria in the airways can cause serious lung damage, including accumulation of scar tissues in the lungs, called fibrosis and cyst formation. Also, it can provoke abnormal work of the digestive system, by blocking intestine and pancreas that are the reason of diarrhea, poor growth, weight loss and diabetes known as cystic fibrosis-related diabetes mellitus (CFRDM). There are several ways to diagnose cystic fibrosis: sweat test, measuring of salt quantity in the sweat, prenatal screening, newborn screening, and genetic testing. (Ratjen F,2003) At the molecular level the reason of cystic fibrosis is mutations in the CFTR gene, full name of which is “cystic fibrosis transmembrane conductance regulator”. “More than 1,000 mutations in the CFTR gene have been identified in people with cystic fibrosis”.² CFTR gene is located on chromosome 7. This gene is responsible for the synthesis of protein called cystic fibrosis transmembrane conductance regulator that is compose channels across the membrane of cells that produce mucus, sweat, saliva, tears, and digestive enzymes. The main function of these channels is to transport chloride ions into and out of cells. It is associated with the water movement in tissues which is an important requirement for the excretion of thin, freely flowing mucus. CFTR gene mutations prevent normal functioning and the flow of chloride ions and water through cell membranes and cause anomaly thick and sticky mucus production. These mutations cause changing in single protein building blocks, called amino acids in CFTR protein or remove a short amount of DNA from the CFTR gene. As a result abnormal channels produced and breaks down quickly, so they don`t arrive to the cell membrane for chloride ions transporting. There are two working copies (alleles) of the CFTR gene in most people. Only one is needed to prevent cystic fibrosis. CF develops when neither allele can produce a functional CFTR protein. Thus, CF is considered an autosomal recessive disease.(Samuel M Moskowitz,2001.) There are different ways by which genes are inherited from our biological parents, autosomal recessive inheritance is one of them. “Autosomal” means that the gene is located on one of the autosomes (chromosome pairs 1 through 22) and males and females are evenly affected. “Recessive” means that 2 copies of the gene are required to have the feature, one from the mother and one from the father. In some cases there is one recessive gene in a person`s genome and this person called a carrier for the trait or disease. But no symptoms of disease are manifested in carriers and such people are absolutely healthy. Usually they don`t know that they carry a recessive mutated gene for a disease. The disease can reveal in their children. There is 25% (one out of four)that parents that carry the recessive gene of cystic fibrosis will have infected child, but 75%( three out of four) that their child will be healthy. (Samuel M Moskowitz,2001.) After thorough analysis of my inheritance I needed additional information about СFTR gene mutations in my genome. I passed a genetic test and identified that I carry the recessive mutated gene` of cystic fibrosis. Consequently, my parents carry the recessive fault CFTR gene. Now I realized that I inherited one abnormal gene and working one. I have a predisposition to cystic fibrosis. Now I know that I am a carrier of cystic fibrosis and the planning of my future pregnancy will require special attention. Ideally to determine the risk that a child will born with cystic fibrosis a couple should have themselves tested for the CFTR gene mutations. Generally, the chance that two partners who carries a gene with a change (mutation) will meet is small, if the partner is not a close relative and does not have a family history of the same genetic problem. But if my future partner will be a carrier of the changed recessive CFTR gene the risk that my future child will have a cystic fibrosis is: “25% chance that a child will inherit the changed gene from each parent (two genes) and have the disease, 50% chance in each pregnancy that a child will receive one changed gene and be a carrier, 25% chance in each pregnancy that a child will not receive the changed gene and be neither a carrier nor have the disease.”¹ There is no chance that my child will be infected by cystic fibrosis when I will only one unaffected carrier of the autosomal recessive faulty gene. When both parents have an autosomal inherited disease such as cystic fibrosis all of their children will also be affected by or predisposed to this disease. In another case when one parent is an unaffected carrier of the autosomal recessive mutated gene and the other parent is affected by the disease, 1 chance in 2 (50% chance) in every pregnancy that they will have a child who inherits both copies of the faulty gene. In this case, the child will be affected or predisposed to develop the condition. “Testing to determine whether an individual is a genetic carrier of a condition is only appropriate if there is a family history of the condition or if the condition is common in their ethnic/cultural group”.³ If my future child will be absolutely healthy and inherited both copies of working CFTR gene nothing won`t threaten to his future children. If a child will have both copies of the faulty, mutated CFTR gene, no working gene product will be produced and their child will be affected by or predisposed to develop the cystic fibrosis. If it will be the faulty copy of the gene and the working copy of the gene in a child from each parent and he/she will be an unaffected carrier of the faulty gene, just like the parents the same. There is 1 chance in 4 (25% ) that they will have a child who inherits both copies of the faulty gene. Anyway, I have to inform my children that there is cystic fibrosis in a family history and genetic testing to determine whether he/she is a genetic carrier is quite important.( WebMD,2012) Therefore, I successfully analyzed my family history of inherited diseases. I detected that my grandmother on mother`s line was infected by cystic fibrosis and my mother received a recessive copy of the mutated CFTR gene, she doesn`t have any symptoms of cystic fibrosis as she is a carrier. My father also has one copy of fault CFTR gene and he also a carrier. The genetic history of his parents is unknown. Obviously that his parents were carriers of mutated CFTR gene and have a predisposition to cystic fibrosis or one of them was infected by cystic fibrosis. I am a healthy carrier like my parents, because I have just one copy of the CFTR gene with the change. REFERENCES: 1. WebMD,2012. Autosomal Recessive Disease-Topic Overview.[online]. Available at:.[Accessed November 29, 2012]. 2. Ratjen F, Döring G.,2003. Cystic fibrosis. Lancet .[online].Available at: http://ghr.nlm.nih.gov/condition/cystic-fibrosis.[Accessed August 2012]. 3. Samuel M Moskowitz,2001. CFTR-Related Disoders.[online].Available at:. Read More