Final answer:
Yes, one can distinguish between a dominant autosomal trait and an X-linked dominant trait in a pedigree. Autosomal traits appear in both genders and do not skip generations, while X-linked dominant traits have a different pattern, particularly in the transmission from affected males to all daughters.
Step-by-step explanation:
It is possible to distinguish between a dominant autosomal trait and an X-linked dominant trait in a pedigree analysis. Understanding patterns of inheritance through pedigrees allows for the recognition of how traits are passed down through generations.
For a dominant autosomal trait, such as free-hanging earlobes, it will be expressed in every generation if it is present, and can be inherited from either parent. The offspring must have at least one affected parent, and the trait can appear in both males and females with equal probability. An X-linked dominant trait, however, will show a different pattern. Since females have two X chromosomes, they can be heterozygous or homozygous for the trait, while males, having only one X chromosome, will always express the trait if they have the mutant allele. A key indicator of an X-linked dominant trait is that affected males will pass the trait to all of their daughters but none of their sons, because sons inherit their father’s Y chromosome.
Males expressing a recessive X-linked allele, such as color blindness or hemophilia, will have received the allele from their mothers, as their X chromosome comes from her, and their Y chromosome comes from their father. For females to express the recessive X-linked trait, they must inherit the allele from both parents, making the trait less common in females.