Passing on genetic information
from parents to children
An explanation of X- linked
inheritance
© 2013 NHS National Genetics and Genomics Education Centre
Genetics and genomics for healthcare
www.geneticseducation.nhs.uk
• Here are some PowerPoint teaching slides which
demonstrate the transmission of an x-linked inherited
condition from parent to child; please feel free to use
these within your teaching
• Some parts of the animations run automatically;
others require a mouse click
• Most slides have notes with further information
© 2013 NHS National Genetics and Genomics Education Centre
Genetics and genomics for healthcare
www.geneticseducation.nhs.uk
The 46 human
chromosomes
seen down the
microscope
Hundreds of genes are located on each chromosome
(The dark bands on the chromosomes are due to a special staining technique and are not genes as these are too
small to see)
© 2013 NHS National Genetics and Genomics Education Centre
Genetics and genomics for healthcare
www.geneticseducation.nhs.uk
The 46 human chromosomes arranged in their 23 pairs
© 2013 NHS National Genetics and Genomics Education Centre
Genetics and genomics for healthcare
www.geneticseducation.nhs.uk
The 46 human chromosomes arranged in their 23 pairs
Sex chromosomes of a male
© 2013 NHS National Genetics and Genomics Education Centre
Genetics and genomics for healthcare
www.geneticseducation.nhs.uk
The 46 human chromosomes arranged in their 23 pairs
Sex chromosomes of a male
© 2013 NHS National Genetics and Genomics Education Centre
female
Genetics and genomics for healthcare
www.geneticseducation.nhs.uk
Males
Position of particular gene
Y chromosome
X chromosome
Females
X chromosome
© 2013 NHS National Genetics and Genomics Education Centre
Genetics and genomics for healthcare
www.geneticseducation.nhs.uk
X-linked inheritance where the mother is a
carrier for an X-linked recessive condition
© 2013 NHS National Genetics and Genomics Education Centre
Genetics and genomics for healthcare
www.geneticseducation.nhs.uk
Males
Altered gene
Y chromosome
Male with an Xlinked recessive
condition
X chromosome
Females
Usual gene
X chromosome
© 2013 NHS National Genetics and Genomics Education Centre
Altered gene
Female who is a carrier for an
X-linked recessive condition
Genetics and genomics for healthcare
www.geneticseducation.nhs.uk
X-linked recessive inheritance where the mother is a carrier
Parents
Father
Mother
Sperm/Eggs
X
Y
X
X
At conception
Daughter
Daughter
Son
Son
X-linked recessive inheritance where the mother is a carrier
Parents
Father
Mother
Sperm/Eggs
X
Female, does not have the
condition, non-carrier
Y
Female, carrier for the
condition
X
Male, does not have
the condition
X
Male, has the
condition
X-linked inheritance where the father has an
X-linked recessive condition
© 2013 NHS National Genetics and Genomics Education Centre
Genetics and genomics for healthcare
www.geneticseducation.nhs.uk
X-linked recessive inheritance where the father has an X-linked condition
Parents
Father
Mother
Sperm/Eggs
X
Y
X
X
At conception
Daughter
Daughter
Son
Son
X-linked recessive inheritance where the father has an X-linked condition
Parents
Father
Mother
Sperm/Eggs
Female, carrier for the condition
Male, does not have the condition
X-linked dominant inheritance
Only a few disorders are known to be inherited in an Xlinked dominant manner.
© 2013 NHS National Genetics and Genomics Education Centre
Genetics and genomics for healthcare
www.geneticseducation.nhs.uk
X-linked dominant inheritance where the
mother has the condition
© 2013 NHS National Genetics and Genomics Education Centre
Genetics and genomics for healthcare
www.geneticseducation.nhs.uk
Males
Altered gene
Y chromosome
Male with an Xlinked dominant
condition
X chromosome
Females
Altered gene
X chromosome
© 2013 NHS National Genetics and Genomics Education Centre
Usual gene
Female who has an
X-linked dominant condition
Genetics and genomics for healthcare
www.geneticseducation.nhs.uk
X-linked dominant inheritance where the mother has the condition
Parents
Unaffected
Father
Mother
Has
condition
Sperm/Eggs
X
Y
X
X
At conception
Daughter
Daughter
Son
Son
X-linked dominant inheritance where the mother has the X-linked condition
Parents
Unaffected
Father
Mother
Has
condition
Sperm/Eggs
X
Y
X
X
At conception
Daughter with condition
Daughter without condition
Son with condition
Son without condition
X-linked dominant inheritance where the mother has the X-linked condition
Parents
Unaffected
Father
Mother
Has
condition
X-linked dominant conditions may be so severe that males with the
condition do not survive
Daughter with condition Daughter without condition
Son with condition
Son without condition
X-linked dominant inheritance where the mother has the X-linked condition
Parents
Unaffected
Father
Mother
Has
condition
So fewer males than expected may be seen in the children of a
mother who has an X-linked dominant condition
Daughter with condition Daughter without condition
Son without condition
This animation is part of a series describing modes of
inheritance
To access these and other resources for teaching and
learning genetics, please visit:
www.geneticseducation.nhs.uk
© 2013 NHS National Genetics and Genomics Education Centre
Genetics and genomics for healthcare
www.geneticseducation.nhs.uk