How could we know whether a trait is autosomal or sex linked by studying a pedigree?

Question

Benjamin Alvin · Accepted Answer

they are distinguished through notation - a sex-linked pedigree will have mostly affected males, the female carriers are typically designated as a half shaded circle.

Autosomal traits can also be identified when a female offspring shows a recessive trait and the father is not affected & if an affected mother has a non-affected son.

Michael Adams · Answer

The discussion below considers only recessive traits.

Distinction 1

In a pedigree displaying autosomal trait, affected individuals are of both sex: that is both male and female individuals could be affected in 1:1 ratio.
In a pedigree displaying sex linked trait, an overwhelming number of males will be affected.
Distinction 2
- In case of autosomal trait, both male and female individuals could be carriers.
- In case of sex linked trait, carriers are always female individuals, never male.
  Distinction 3
  - An autosomal trait generally appears to affect individuals in every generation.
  - A sex linked trait shows 'criss cross inheritance'.

Michael Adams · Answer

undefined By studying a pedigree, we can determine whether a trait is autosomal or sex-linked by observing its pattern of inheritance across generations. Autosomal traits typically affect both males and females equally and appear in both sexes in roughly equal proportions in each generation. In contrast, sex-linked traits show a distinct pattern, where males are more commonly affected than females, and the trait is often passed from an affected mother to all of her sons.