Genetics Pedigree Diagram

In summary, the conversation discusses a pedigree diagram and attempts to determine the mode of inheritance for a disease based on the pattern of affected individuals. The possibility of X-linked dominant inheritance is considered, but it is noted that affected males do not pass the condition on to their female offspring. Other possibilities such as X-linked recessive, autosomal dominant, and autosomal recessive inheritance are suggested, and it is recommended to consider the possible genotypes of the original progenitors and their offspring to determine which hypothesis is consistent with the observed pattern.
  • #1
nokia8650
219
0
I was struggling with interpreting the following pedigree diagram:

http://img245.imageshack.us/img245/715/photoon20100411at2211.jpg [Broken]

I can see from the diagram that only females seem to be capable of transmitting the disease - not males - this lead me to believe it is X-linked. In addition, I noted that EVERY offspring of an affected female is also affected; leading me to believe it is dominant. This lead to me thinking the condition was inherited in an x-linked dominant manner. However, this would not explain why affected males (who would in my model have the dominant disorder on their X chromosome) do not pass on the condition to their female offspring.

Any help is greatly appreciated.. thanks!
 
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  • #2
nokia8650 said:
However, this would not explain why affected males (who would in my model have the dominant disorder on their X chromosome) do not pass on the condition to their female offspring.

That appears a conclusive objection!
So you have to consider other possibilities.
 
  • #3
thanks for the reply! I can't really think of anything... would it be possible for you to nudge me in the right direction? Thanks
 
  • #4
Just go through X-linked recessive, autosomal dominant and recessive, start with the possible original progenitors' constitution (e.g. original mother must be AA if it is recessive whereas...) write down then the possibilities for F1 etc. and see for each whether there is anything that happens that would be impossible with each starting hypothesis. You cannot offhand predict whether the possibilities are unique or more than one hypothesis is consistent, perhaps someone practiced could see it immediately, not me either.
 
  • #5


As a scientist, it is important to carefully analyze and interpret data in order to make accurate conclusions. Based on the pedigree diagram provided, it does appear that the disease is inherited in an X-linked dominant manner. This is supported by the fact that affected females pass the condition on to ALL of their offspring, and affected males do not pass it on to any of their offspring. This is a characteristic of X-linked dominant inheritance.

However, one possible explanation for affected males not passing on the condition to their female offspring could be that the condition is lethal in males. This means that affected males may not survive to pass on the condition to their offspring, resulting in a lack of affected females in the pedigree. It is also possible that there are other factors at play, such as incomplete penetrance or variable expressivity, that could influence the inheritance pattern.

It is also important to consider the possibility of genetic testing to confirm the mode of inheritance in this case. By analyzing the DNA of affected individuals and their family members, it may be possible to identify the specific gene and mutation responsible for the disease and determine the exact inheritance pattern.

In conclusion, while the pedigree diagram does suggest X-linked dominant inheritance, there may be additional factors at play that warrant further investigation. As a scientist, it is important to continue to analyze and question the data in order to gain a deeper understanding of the genetic mechanisms at work.
 

1. What is a Genetics Pedigree Diagram?

A Genetics Pedigree Diagram is a visual representation of the genetic relationships within a family. It shows the presence or absence of a particular trait or condition in individuals across multiple generations, allowing scientists to track the inheritance pattern of a specific gene or trait.

2. How is a Genetics Pedigree Diagram created?

A Genetics Pedigree Diagram is created by gathering information about the family's medical history and analyzing the presence or absence of the particular trait or condition in each individual. This information is then organized and represented in a standardized format using symbols and lines to indicate the genetic relationships between family members.

3. What are the symbols used in a Genetics Pedigree Diagram?

The symbols used in a Genetics Pedigree Diagram include squares for males, circles for females, and different types of shading or symbols to indicate the presence or absence of a certain trait or condition. Other symbols may also be used to represent genetic relationships, such as lines connecting parents and children, and double lines for twins.

4. What can we learn from a Genetics Pedigree Diagram?

A Genetics Pedigree Diagram can provide valuable information about the inheritance pattern of a particular trait or condition within a family. It can also help identify carriers of a genetic disorder, predict the likelihood of a person developing a certain condition, and provide insights into potential genetic risks for future generations.

5. How is a Genetics Pedigree Diagram used in scientific research?

A Genetics Pedigree Diagram is an important tool in genetic research as it allows scientists to study the inheritance patterns of specific genes or traits in a controlled and systematic way. It can also help identify potential genetic links to certain diseases or conditions and inform the development of new treatments or prevention strategies.

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