Question

Is the trait autosomal or sex-linked? Give reason.

Answer 1

• We first check whether the pedigree is sex-linked. If not then it is taken as autosomal.
  
• The trait is not Y-linked as in Y linked, only males are affected.
  
• The trait could be X-linked. But, it is not X-linked recessive because there are no generation skips.

Hence, it could be X-linked dominant.

• The female in the parent is unaffected and the male has only one X chromosome, so the genotypes could be XX and X$c$X. But since in the next generation both the females are not similarly affected according to the above cross, the trait must be autosomal.
• In autosomal traits, both males and females are affected equally regardless of their sex.
  

So, the correct option is 'autosomal'.