Class Activity: PCB3063 RVEC 12, NU My FIU Group Jack 6: Genetics Chapter 6: Not Online Live Worksheet File Edit View Insert Format Tools Add-ons Help Last edit was seconds ago 100% Normal text Arial I 4 A First cousins 40. What type of inheritance does this pedigree demonstrate? Autosomal Recessive Autosomal Dominant Y-Linked X-Linked Recessive 41. Write the appropriate mode of inheritance in red next to the appropriate trait; som
The Correct Answer and Explanation is:
Correct Answer for Question 40:
Autosomal Recessive
Explanation
The pedigree provided demonstrates an autosomal recessive mode of inheritance. This type of inheritance occurs when two copies of an abnormal gene must be present for the trait or disorder to develop. Individuals who inherit only one copy of the gene are typically asymptomatic carriers.
There are several key characteristics of autosomal recessive inheritance that are likely evident in this pedigree:
- Affected individuals often have unaffected parents. In autosomal recessive traits, both parents of an affected individual are usually carriers (heterozygotes) who do not show the trait themselves. This results in a 25% chance that their child will be affected if both parents are carriers.
- The trait often appears to skip generations. Because carriers are asymptomatic, the trait may not be expressed in every generation.
- Males and females are affected equally. Since the gene is located on one of the autosomes (non-sex chromosomes), both sexes have the same probability of inheriting the mutation.
- Consanguinity (inbreeding) increases the risk. The pedigree notes that the parents are first cousins, which increases the likelihood that both parents carry the same recessive allele inherited from a common ancestor. This is a strong indicator of autosomal recessive inheritance, as rare recessive alleles are more likely to pair up when close relatives reproduce.
- Affected individuals may have affected siblings but not necessarily affected parents. This is a hallmark of autosomal recessive traits.
Therefore, based on the pattern of affected individuals, equal sex distribution, and the presence of consanguinity, autosomal recessive is the most appropriate classification for the inheritance pattern observed in this pedigree. Recognizing this mode of inheritance is crucial in genetics as it guides genetic counseling, carrier testing, and risk prediction for future offspring.
