Step I activating mutation in Achondroplasia

[stronghold]

I noticed UW states that the defect of FGFR3 is dude to activating mutation. Does that mean the mutation stimulates and increase the activity of FGFR3? I previously thought the mutation decreases the activity of that receptor

 

[thawunandonly]

Isn't FGFR3 responsible for inhibiting differentiation or chondrocyte proliferation? So if you over-activate it -> stunted growth/cartilage of long bones

 

[Manu9]

Basically you get a gain of function mutation in the FGFR3 gene which inhibits chondrocytes so no proliferation of cartilage at the growth plate which is why the face bones are not affected since they do not require cartilage