SADDAN is caused by mutations in the FGFR3 gene.

 

Researchers believe that this mutation strongly over activates the FGFR3 protein, which leads to severe disturbances in bone growth. It has not been determined how the mutation affects brain development or causes acanthosis nigricans (a skin disorder characterized by thick, dark, velvety skin).

 

Thanatophoric dysplasia, type 1 is caused by mutations in the FGFR3 gene.

 

At least 10 mutations in the FGFR3 gene have been shown to cause type 1 thanatophoric dysplasia. Most of these mutations substitute an incorrect amino acid in the fibroblast growth factor receptor 3 protein. The mutated receptor is over activated, causing the severe problems with bone growth seen in this condition. It is unclear how FGFR3 mutations lead to the brain and skin abnormalities associated with thanatophoric dysplasia.

 

Thanatophoric dysplasia, type 2 is caused by mutations in the FGFR3 gene.

 

Only one mutation has been shown to cause type 2 thanatophoric dysplasia. Researchers believe that the mutation causes the receptor to be overactive, leading to the severe problems with bone growth seen in this condition. It is unclear how this mutation causes the brain and skin abnormalities associated with thanatophoric dysplasia.

 

Bladder cancer is associated with the FGFR3 gene.

 

Some gene mutations are acquired during a person's lifetime and are present only in certain cells. These changes are called somatic mutations and are not inherited. Somatic mutations in the FGFR3 gene are associated with some cases of bladder cancer. The mutations over activate the fibroblast growth factor receptor 3 protein, which likely directs bladder cells to grow and divide in the absence of signals from outside the cell. This uncontrolled cell division leads to the formation of a bladder tumor.