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

2 Answers
Jun 26, 2017

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.

Jun 28, 2017

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'.