Transcript Genetics & Evolution Series: Set 4

Sex Linkage
Sex-linked traits show a
distinct pattern of inheritance.
Carrier
mother
Unaffected
father
Fathers pass sex-linked
alleles to all their daughters
but not to their sons.
X
Mothers can pass sex-linked
alleles to both sons and
daughters.
Y
X
X
In females, sex-linked
recessive traits will be
expressed only in the
homozygous condition.
In contrast, any male
receiving the recessive
allele from his mother will
express the trait.
XY
XX
Unaffected
son
XX
Unaffected
daughter
Carrier
daughter
XY
Affected
son