Sex linkage refers to a trait that is carried on a sex chromosome like the X chromosome. Because someone might have a different number or combination of sex chromosomes such as a single X chromosome or two X chromosomes, the expression of various traits can differ.
If for example the allele on the affected X chromosome means that an essential protein isn’t being made, the carrier XX child has another unaffected X chromosome to fall back on and be able to produce the essential protein. The carrier XY child only has the affected X chromosome and cannot make the protein. This results in an illness for example, such as haemophilia. Haemophilia is a blood clotting disorder in which excessive bleeding takes place because the platelet plug and fibrin which are supposed to stop bleeding do not work fully.
Another example of an X-linked condition is Duchenne muscular dystrophy which affects around 1 in every few thousand children with an XY genotype. It is a progressive muscle degeneration condition that affects mobility, and in the long term requires assistive ventilation devices, with an overall impact on life expectancy.
The inheritance pattern matches that of haemophilia.
OMG them videos are great! You're a goldmine - and I'm a gold digger ;)
I’ve struggled so much with feeling overwhelmed with biology revision, and I don’t know where to start. But your website is just what I need! It tells me all the information I need, and the knowledge I need to then build on, and it’s written in a way that soaks straight up into my brain!
Prettyhetty The Student Room
You explain everything so simply!
SecretDuck The Student Room
I got A* in A-level biology (Cambridge), thanks! I love your videos
Sherif Negm Facebook
You're such a G. Helped me so much, finally found someone who breaks biology down into something I can understand!!!
Alex Contact Form