Submitted the document for the case study in \"Long QT Syndrome\" and it contain
ID: 85722 • Letter: S
Question
Submitted the document for the case study in "Long QT Syndrome" and it contained the following:
Description of how incomplete penetrance, variable expressivity, pleiotropy, and genetic heterogeneity can affect the severity of a disease in a family.
Analysis and justification for why approaches, such as exercising regularly and following a diet low in saturated fats and simple carbohydrates and high in fruits and vegetables, are ineffective against long QT syndrome (LQTS).
Explanation for how the molecular bases of the various forms of LQTS make genetic heterogeneity very likely.
Explanation / Answer
LTQS is a congenital disease and it is very rarely seen, its occurrence through inherited or acquired heart condition, where we see the heart beat increases abnormally originating from ventricles and delayed repolarization occurs.
This disease is traced back and studies with genetic heterogeneity and penetrance with variable expressions to find out that it is caused by mutations. There are at least 10 genes those are essential for a cell protein formation of ion channels gets disrupted by mutations, those channels are like potassium, sodium, or calcium channels. Now this is important because ion channels are important to drive and carry forward the nerve impulses and the resulting muscle contraction.
In case of hearts we have to know the functionality associated with heart beat the rhythm in which it works. After a beat, called repolarization after a hearts recovery, extends the process of ions recovery from the useful channels those are usually trapped inside heart muscle cells. Now these could be too slow or fast to open such channels, a jerk occurs for those persons who all are inherited mutation. Even people with this disease experiences arrhythmia if they are in drug or medications that prolong the QT internal of heart.
In case of incomplete penetrance and variable expressibility, we have seen is that it could be seen in autosomal dominant pattern of inheritance. i) Incomplete penetrance: here with people a particular genetic mutation shows signs and symptoms with genetic disorder. Incomplete penetrance because in future he condition said to have reduced penetrance. Only through a personal medical of family history shows the passing of a genetic information like in case of LQTS. ii) Variable expresibility- here the affected individuals are having variable mode of expression for the same disease, in case of LQTS this occurs, where the same family members having this genetic disease shows different patterns or symptoms. A combination of genetic and environmental or eve lifestyle factors to foster this disease.
This monogenic disease known as LQTS mode of inheritance is autosomal dominant form of genetic pattern. This diseases clinical manifestations shows different genetic background. The disease causing gene is mainly determined for the genetic background to check for. Here the genetic phenotype is very important to understand and observe, and the specific gene performs severity from the mutation in their gene.
LTQS also refers to a "group of “channelopathies” that alters and affects by the ion channels is having family traits genetically to follow and inherited in an individual. One of the heterogenic condition have seen in multiple LQTS genotypes, LQT 1-8, this even shows some converging mechanisms which have reported to be QT prolongation patterns and connected with ventricular repolarization. Genetic heterogeneity is very evident in this case as it has been seen through vaious world populations, the polymorphic patterns for example HERG P448R and A915V in Asians, and SCN5A S1102Y in African Americans, are evidences have been seen, there are many other genetic polymorphic patterns to follow.