Any kind of genetic disorder can be diagnosed properly by critically examining a pedigree chart. It helps in understanding the sources and type of any particular disease. The risk of any genetic disorder can be reduced by valuing a family pedigree chart. In preparing this chart, some important specifications are utilized and properly followed.
A pedigree chart is useful in understanding the different genetic characteristics of any organism. In a pedigree chart, a diagram is prepared in which the occurrence types and forms of different phenotypes are included. In a whole pedigree chart, some symbols are used. In presenting males, a square is used and for a female, a circle is used.
Figure 1: Useful symbols of a pedigree chart
In this type of chart, the sibling line, line of descent and marriage line are three other significant symbols of presenting relationships. Different appearances of any particular gene and their relationship with ancestors are the two most important concerns of such a chart. The generation-wise changes and their impacts on different characteristics of organisms can be analyzed based on a properly developed pedigree chart.
The main aim is to develop a proper pedigree chart with which every single genetic detail about any family can be detected.
All the relevant information about a family and its members is necessary. Persons of more than one generation are also required in developing such a chart.
At the very first stage, a family is to be chosen in which one member possesses monogenic traits. Some examples of important monogenic traits are blood groups, rolling of the tongue, lobes of the ears, colour blindness, and peak of a widow.
One of the family members is to be questioned about other members’ characteristics and traits.
All the collected data and information is to be noted at a place and the chart is to be prepared based on that.
Based on the completed chart, the nature of a particular disease is to be understood. The disease may be of the type autosomal recessive or can be autosomal dominant.
A critical and in-depth review of the chart may assist a person to understand the exact type of the disease.
Based on this prepared chart, Y-linked recessive and dominant and with that Xlinked recessive and dominant characteristics are also found.
Some of the most important autosomal dominant traits are widow’s peak, hanging earlobes, tongue rolling and blood groups. In relation to this specific type of trait, all the mutant alleles are dominant in nature. This trait is generally transmitted to the children from parents. Both males and females can be affected by these traits. The pedigree, being vertical, is present in every single person of the following generations.
This type of trait is recessive in nature. Some most significant features of these traits include multiple numbers of traits, available in both the male and female siblings. Parents can be heterozygous whereas the siblings are homozygous the result of some defective alleles.
Figure 2: Diagram of autosomal recessive inheritance
In exhibiting this particular trait, genetically related men and women are to be married to each other.
This type of generation trait is an important part of a pedigree chart. The location of this trait is a chromosome. In this particular trait, the mutant allele is found to be dominant. In almost all generations, inheritance’s nature is vertical.
Figure 3: Presentation of X-linked dominant inheritance
As a result of this, a female being affected by this trait passes this to half of the next generation, mainly to the sons. In reverse, in case the male person is affected, the daughters are mainly affected by this trait.
In relation to this particular type of trait, all the mutant alleles are recessive in nature and of the wild allele. The traits are fully expressed by women who are homozygous in nature. In male figures, the nature of the males has to be hemizygous. In the case of a female carrier of this trait, half of the sons are affected whereas a homozygous female affects half of the daughters and 100% of sons by this trait.
This particular trait is present only in the Y-chromosome. Males possess all the associated traits with Y-chromosomes. Sons are affected by this trait and no daughter can be affected because this trait is not available in any female body.
Inheritance-related information can be analyzed by evaluating all associated characteristics of a pedigree chart. For instance, in determining the tongue rolling capability of a person, various factors play an important role. Only one gene is capable of setting characteristics order in a body. No such kind of male-to-male transmission of X-linked dominant traits is found. Characteristics of such traits are the main reason behind a highly affected male population by these traits. No female body can be the carrier of the Y-chromosome trait.
Q1. What is a pedigree genetic chart?
Ans. This type of chart is prepared based on family genetic history. Some important standardized symbols are there that are used in depicting some of the most important genetic information about a family. Based on such a chart, significant information and relationship among all the family members can be analyzed.
Q2. Which types of patterns are shown in a pedigree chart based on inheritance?
Ans. In understanding each characterized component of a family’s members, inheritancerelated information is very crucial. There are four main patterns namely, recessive, dominant, sex-linked, and autosomal.
Q3. Which type of variation is associated with tongue rolling?
Ans. This type of action is integrally connected to the discrete variation. A small amount of gene’s presence in a cell is the main reason behind this.
Physics
Biology
Chemistry
Mathematics
Economics
Psychology
Environmental Science
Social Studies
Fashion Studies
English