Question

Question 2: Explain how to read the chart by indicating what the squares and circles represent and what is the difference between filled and hollow shapes.

Question 3: Discuss what conclusions can be drawn from the pedigree eg assuming that the disease is caused by the mutation of one single gene, do you think this mutation is recessive or dominant? Are the affected individuals more likely to be heterozygous or homozygous for this mutation? Is the disease affecting equally men and women? For each conclusion, make sure to explain how it is supported by the pedigree.

Answer 1

2. In the pedigree the genetic history of the whole family is represented. The square shaped figures represent the male individuals and the circle represents the female individuals. If the square or circle figures are hollow then they do not have any genetic disorder manifested in their phenotype. If they are represented by black filled squares or circle then the individual is carrying a genetic disorder.

3. As no pedigree has been provided, i am just taking the example of the following pedigrees to explain them:

for the autosomal disorders, if the gene is affecting the individual in a dominant manner, then if both the parents are heterozygous then the parents get affected and the children who are homozygous dominant or heterozygous will get affected, but recessive individuals will be normal. In autosomal recessive individuals, homozygous dominant and heterozygous individuals will be normal but the homozygous recessive individuals will be affected. Same is in the case of allosomal inheritance, the only difference being whether the mutation is on X or the Y allele. If the mutation is on the X allele and inheritance pattern is recessive,then the females who are heterozygous will act as carriers but males who have only one X allele will get affected if they inherit the recessive allele. In dominant case both the sexes are affected in equal manner. If the inheritance is due to the mutation in Y allele, then the males are more affected. These are the different types of pedigree that can be observed in different inheritance pattern.

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