Sex linked inheritance

1. SEX-LINKED
INHERITANCE
BY: MRS. PRECILLA C. STEPHEN

2. DEFINITION
◦ It is the inheritance of a trait(phenotype)
that is determined by a gene located on one
of the sex chromosome.
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4. X-LINKED
DOMINANT
INHERITANCE
◦ Dominant gene is carried on the X-gene
◦ Male – get their X-chromosome from their
mother
◦ Females – get their X-chromosome from both of
their parents
◦ If the mother is a carrier of the mutated gene
◦ 50% of the son or/and daughter will be affected
◦ 50% of the son or/and daughter will be normal 4

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7. X-LINKED
DOMINANT
INHERITANCE
◦ If the father is a carrier of the mutated
gene
◦ 100% of his daughter will have the
disorder
◦ 0% of his son will have the disorder
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9. X-LINKED
DOMINANT
INHERITANCE
◦ If both parents are a carrier of the
mutated gene
◦ 100% of his daughter will have the
disorder
◦ 50% of his son will have the disorder
◦ 50% of his son will be unaffected or
normal 9

10. X-LINKED
RECESSIVE
INHERITANCE
◦ A mode of inheritance on the X-
Chromosome that causes the phenotype
to be expressed
◦ Female carriers have only copy of the
gene and usually don’t express the
phenotype.
◦ Ex: Color blindness, haemophilia 10

11. Y- LINKED
INHERITANCE
◦ Holandric Inheritance
◦ Y-chromosome is small and doesn’t
contain numerous genes
◦ Y-linked diseases or disorder are very
rare
◦ It occurs between fathers and his sons.
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