In a Y-linked disorder, only males can be affected. If the father is affected all sons will be affected.
Who is affected in a pedigree?
An individual in the pedigree will be affected (express the phenotype associated with a trait) when the individual carries at least one dominant allele of a dominant trait, or two recessive alleles of a recessive a trait. generations are not carriers.
Can males be carriers in pedigrees?
A male never passes an x-linked trait to a son. An unaffected male cannot be a carrier and cannot transmit a disease allele to any child.