Question

The genotype of the individual marked 2 on the pedigree shown could father children with all of the following genotypes except-

A. ${{X}^{A}}{{X}^{a}}$
B. ${{X}^{a}}{{X}^{a}}$
C. ${{X}^{A}}{{X}^{A}}$
D. ${{X}^{a}}Y$
E. ${{X}^{A}}Y$

Answer 1

Pedigree chart refers to a diagram that represents the appearance and occurrence of phenotypes of an organism or a particular gene inherited from its ancestors from one generation to the next generation. A pedigree chart is an easily readable chart that gives information about a family.

Complete step-by-step answer:
In simple words, pedigree charts can be called family trees. Standardized sets of symbols are used in pedigree charts. Squares in pedigree charts represent males and circles in pedigree charts denote female members of a family. Horizontal lines connect the parents and Offsprings are connected by vertical lines. The pedigree chart shows the family history and details about an earlier generation. A diamond symbol is used if the sex of the person is unknown. The phenotype of the individual is shown with the help of filling the square or circles of the pedigree chart. Males are more likely to be affected than females in X- linked recessive disorder. The mutations of genes in the X chromosome in X-linked recessive disorder cause the phenotype to be expressed in males and in females who are homozygous for the gene mutation. Thus, only homozygous recessive females with ${{X}^{a}}{{X}^{a}}$ are able to affect the son with chromosomes ${{X}^{a}}Y$. As the affected individual is male, its chromosome is ${{X}^{a}}Y$.

So, option D is the correct option.

Note: A generation is skipped in X- linked recessive disorder. Therefore, Offspring with the trait have normal parents who act as a carrier and are not affected by abnormal genes. X- linked recessive disorder cannot be transmitted to the son from the father.