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Pedigree construction and analysis

TASK INSTRUCTIONS: Prepare a three-page report in which you draw and analyze the pedigree of the following family.

Subject: affected woman
Subject's two brothers, unaffected
Subject's father affected, mother unaffected
Subject's paternal aunt and uncle, unaffected
Subject's paternal grandfather affected, grandmother unaffected

In your 3-page report, present the following:

1. Introduction Introduce the problem and list the data.

2. Pedigree Chart Draw the pedigree according to the standard format.

3. Identification Identify each individual in the pedigree with a number.

4. Analysis In the Analysis section, make a section for possible modes of inheritance (autosomal dominant, autosomal recessive, X-linked dominant, X-linked recessive, Y-linked).

5. Within each section assign putative genotypes to each individual in the pedigree (you may do this by labeling a diagram or listing the individuals). State whether the mode of inheritance is possible given the pattern in the pedigree. Make any other relevant comments.

6. Conclusion State the conclusion of the analysis.

Note: When using sources to support ideas and elements in a paper or project, the submission MUST include APA formatted in-text citations with a corresponding reference list for any direct quotes or paraphrasing. It is not necessary to list sources that were consulted if they have not been quoted or paraphrased in the text of the paper or project.

Solution Preview

Attached is the pedigree (I think it's coming in upside down from what I can see, but orientation from numbers written on it should be clear). Males are squares and females are circles. Shaded figures are affected individuals. The original presenting affected woman is the proband and has the arrow pointing to her.

The top row is the oldest generation (grandparents), middle row is parents, aunts and uncles, bottom row is proband and siblings.

Each generation has a roman numeral and each individual has a number. Therefore each person can be uniquely identified by roman numeral/number combination.

The proband is III3. Her affected father is II3. Her affected grandfather is I1.

Modes of inheritance:
There are few that are completely ruled out. Since there is an affected woman, the mode of inheritance cannot be Y-linked as she had no Y chromosome. Also ruled out is X-linked dominant. Since the grandfather cannot pass an X chromosome to the father (males only pass Y chromosome to their sons) then in order for this to be X linked dominant that would mean the grandmother would have to have it. As she is unaffected, this mode of inheritance is impossible. Another mode of inheritance (not mentioned above) ...

Solution Summary

A pedigree is constructed and various modes of inheritance are analyzed and discussed.