Pedigree Overview
Observe the inheritance of traits among your parents and siblings through pedigree
Sketch you family tree
Pedigree is a chart created for families that sketches the genetic disorders and traits that occur in offsprings due to inheritance.
A pedigree could be used to predict information about genetic disorders. It proves the presence or absence of a trait or disease occurring in every individual.
Drawing a pedigree chart may be more like sketching a free tree that shows the inheritance of traits and many other genetic possibilities within the parent and offspring.
This family tree may lead through symbols that indicate basic specifications.
Distinguish between the modes of inheritance
The pedigree chart will include information about the disorders related to every single individual of the family.
The pedigree chart can also distinguish between the diseases caused due to inheritance only if the disorder occurs in more than one individual.
If only a single individual is affected by a disease, then it may not be proved helpful in distinguishing the particular mode of inheritance.
However, it may provide specific information and clues about the mode of inheritance of a trait or a disorder if more than one individual is affected.
Predict and prevent
Sketching a family tree not only enables one to know the inheritance of trait but also predicts which of the individual is at the risk of getting the disease.
If some people have an interpretation of getting a specific disorder, then rapid genetic testing is recommended.
Pedigree is an inheritance pattern that, other than predicting and identifying, can also help you get through many disorders. Pedigree analysis is considered significant as it helps in determining how a trait shall pass in the future.
Identification through analysis
You can identify genotypes and phenotypes by analyzing a pedigree chart. Pedigree gives us information about how certain alleles are inherited.
- Two possibilities are there:
- Either the trait is dominant or recessive.
- Either the chart shows it is autosomal or x-linked.
A trait cannot be both dominant and recessive. Neither can it show autosomal and x-linked behavior together.
Another thing that pedigree analysis gives is that it determines either the individuals with the trait are;
- Heterozygous that means having two different alleles
Or
- Homozygous that means to have two same alleles.
Dominant trait
In the case of a dominant trait, one of the parents must have the trait. The dominant trait does not skip the generation. It occurs if any of or both of the parents are affected. It cannot occur if none of the parents is affected.
With dominant inheritance, all affected individuals will have one dominant allele. They may be homozygous or heterozygous.
Recessive trait
If the trait is recessive, neither parent is required to have the trait. It may occur even if none of the parents is affected. A recessive trait could be heterozygous.
X-linked trait and its division
Mostly in x-linked traits, males are more commonly affected than females. Where the number of males affected is larger than that of females, than the chart suggests that the trait is an x-linked trait. The trait may be recessive x-linked or dominant x-linked, but the sex linked trait is usually recessive.
X-linked recessive
X-linked recessive affects almost males. It is not transmitted from father to son. Mostly the traits of the male are transmitted to females, so if the father is affected, it is inherited to the daughter. All these conditions are applicable for x-linked recessive.
X-linked dominant
AS x-linked occurs when the number of males is more affected by females. All the daughters of the affected father exhibit the trait while the sons of the unaffected mother will not have the trait. These conditions make the x-linked dominant.
Autosomal trait and its condition
If females and males are equally affected, then it proves that the trait is an autosomal trait. It either is an autosomal dominant trait or autosomal recessive trait. The symbols specified in the pedigree inheritance pattern can help you read the chart.
Autosomal recessive
Autosomal recessive may occur when affected offsprings give birth to unaffected offspring. In the other case, both affected parents give birth to offsprings that all exhibit the trait. Moreover, it affects either sex. All these conditions indicate the trait to be autosomal recessive.
Autosomal dominant
While in the case of autosomal dominant, the affected individual has one of the parents itself affected. Here children with one affected parent have a 50% risk of being affected. It may also affect either sex. These conditions mostly predict the pedigree pattern to be autosomal dominant.
How to read?
In a pedigree, males are symbolized by squares while circles represent females. A horizontal line joining a male and female indicates that they had an offspring.
Whereas the vertical line indicates offsprings which are lined up in the order of left to right.
Arranged in the order of birth, the shaded circle or square part indicates the individual who has the trait being traced.
If one of the parents has been affected, then the trait is said to dominate, and if none of the parents is affected, then the trait is recessive.
If any of the individuals are affected, it does not proves that the trait is dominant. If a trait is often showed in a family, it cannot refer it to be dominant as they refer to the way trait is expressed.
You may also not be able to figure out the genotype of an individual on the pedigree.
Growth and development history
Pedigree or a family tree can predict many disorders, even for transplantation. You may have to go pedigree analysis. It also shows family health history. Pedigree is an inheritance pattern that contains ns all of growth and development history.
Pedigree also includes details of symptoms, preservations, and progressions of a family sketching their health history and help in predicting the inheritance of traits and the individuals affected.
Family screening
The pedigree analysis allows for family screening. It can identify who may be at the risk of inheriting the disorder. For families in which the disease-causing mutation is identified, they must be recommended genetic testing, and in this case, the pedigree analysis may help much.
Attributes
- Pedigree is a chart that shows the inheritance of a trait.
- It is created for families which outlines the pattern of traits and genetic disorders.
- It identifies the risk of individuals being affected in the future.
- The pedigree chart contains symbols that enable you to understand and analyze the chart.
- Pedigree is considered as a family tree that indicates the family health history.
- In this family, tree circle symbolizes females while squares symbolize males.
- Pedigree analysis is significant for identifying the disorder or trait caused by a genetic mutation.
- It helps to identify genotypes and phenotypes.
- The trait may be of four types:
- Autosomal dominant
- Autosomal recessive
- X-linked dominant
- X-linked recessive
- They may be homozygous or heterozygous.
- Pedigree provides proof about the mode of inheritance only if more than one individual is affected.
- If many individuals are affected, it does not proves that the trait is dominant.
Moreover, it does not always identify the genotype.
In Pakistan, pedigree also holds significance as it is basically for families.
People consider it as their family health history and helps in predicting the traits and disorders that occur due to mutation. If you understand the symbols, you can effectively analyze the pedigree chart.