Explanation of X-Linked inheritance

1. Passing on genetic information from parents to children An explanation of X- linked inheritance

2. 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

3. 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) The 46 human chromosomes seen down the microscope

4. The 46 human chromosomes arranged in their 23 pairs

5. The 46 human chromosomes arranged in their 23 pairs Sex chromosomes of a male

6. The 46 human chromosomes arranged in their 23 pairs Sex chromosomes of a male female

7. Males X chromosome Y chromosome Females X chromosome Position of particular gene

8. X-linked inheritance where the mother is a carrier for an X-linked recessive condition

9. Males X chromosome Y chromosome Females X chromosome Altered gene Male with an X-linked recessive condition Altered gene Usual gene Female who is a carrier for an X-linked recessive condition

10. Parents Sperm/Eggs At conception X-linked recessive inheritance where the mother is a carrier Father Mother X Y X X Daughter Daughter Son Son

11. Parents Sperm/Eggs X-linked recessive inheritance where the mother is a carrier Father Mother X Y X X Female, does not have the condition, non-carrier Female, carrier for the condition Male, does not have the condition Male, has the condition

12. X-linked inheritance where the father has an X-linked recessive condition

13. Parents Father Mother X Y X X Daughter Daughter Son Son X-linked recessive inheritance where the father has an X-linked condition Sperm/Eggs At conception

14. Parents Father Mother X-linked recessive inheritance where the father has an X-linked condition Sperm/Eggs Female, carrier for the condition Male, does not have the condition

15. X-linked dominant inheritance Only a few disorders are known to be inherited in an X-linked dominant manner.  

16. X-linked dominant inheritance where the mother has the condition

17. Males X chromosome Y chromosome Females X chromosome Altered gene Male with an X-linked dominant condition Usual gene Altered gene Female who has an X-linked dominant condition

18. Parents At conception Father Mother X Y X X Daughter Daughter Son Son Has condition Unaffected Sperm/Eggs X-linked dominant inheritance where the mother has the condition

19. Parents At conception Father Mother X Y X X Daughter with condition Daughter without condition Son with condition Son without condition Has condition Unaffected Sperm/Eggs X-linked dominant inheritance where the mother has the X-linked condition

20. Parents Father Mother Daughter with condition Daughter without condition Son without condition Has condition Unaffected X-linked dominant inheritance where the mother has the X-linked condition Son with condition X-linked dominant conditions may be so severe that males with the condition do not survive

21. Parents Father Mother Daughter with condition Daughter without condition Son without condition Has condition Unaffected X-linked dominant inheritance where the mother has the X-linked condition So fewer males than expected may be seen in the children of a mother who has an X-linked dominant condition

22. 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