Question

homework - genetic tools
study the pedigree.
key
unaffected male
affected male
unaffected female
affected female
which pattern of inheritance is shown?
autosomal dominant
autosomal recessive
sex - linked
polygenic

Explanation:

1. Autosomal dominant:

• In autosomal - dominant inheritance, affected individuals have at least one affected parent (assuming no new mutations). In the given pedigree, affected parents (first - generation male and female) have affected and unaffected children.
• For an autosomal - dominant trait, if a parent has the trait (heterozygous or homozygous dominant), there is a 50% (if heterozygous) or 100% (if homozygous dominant) chance of passing the trait to their offspring. Here, the pattern of affected parents having both affected and unaffected children is consistent with autosomal - dominant inheritance (where parents are likely heterozygous).

1. Autosomal recessive:

• In autosomal - recessive inheritance, often unaffected parents (carriers) can have affected children. But in this pedigree, the first - generation parents are affected. If it were autosomal recessive, two affected parents (homozygous recessive) would have all affected children, which is not the case here.

1. Sex - linked:

• In sex - linked (e.g., X - linked) inheritance, there is a sex - bias. For X - linked recessive, males are more often affected, and for X - linked dominant, there are specific patterns related to father - daughter and mother - son inheritance. In this pedigree, there is no clear sex - specific bias (e.g., equal number of affected males and females in the second generation) that would strongly indicate a sex - linked pattern.

1. Polygenic:

• Polygenic traits are influenced by multiple genes and often show a continuous variation (e.g., height, skin color). Pedigrees for polygenic traits do not show the simple clear - cut affected/unaffected patterns as in single - gene (Mendelian) inheritance shown in this pedigree.

Answer:

autosomal dominant