You will be shown biomedical passages and your task is to the answer the provided question. Provide a concise and accurate response and do not include any additional text in the response other than the answer.

Question: How many different mutations have been associated with Muenke syndrome?

Context: Muenke syndrome is an autosomal dominant craniosynostosis syndrome resulting from a defining point mutation in the Fibroblast Growth Factor Receptor3 (FGFR3) gene.
The associated of FGFR3 mutations with craniosynostosis has been restricted to three mutations, the common p.Pro250Arg in Muenke syndrome, p.Ala391Glu in Crouzon syndrome with acanthosis nigricans, and p.Pro250Leu identified in a family with isolated craniosynostosis.
The Pro250Arg mutation in the FGFR3 gene is found in patients with Muenke syndrome and is one of the most frequently encountered mutations in craniosynostosis syndromes.
Fibroblasts from 10 individuals each with Apert syndrome (FGFR2 substitution S252W), Muenke syndrome (FGFR3 substitution P250R), Saethre-Chotzen syndrome (various mutations in TWIST1) and non-syndromic sagittal synostosis (no mutation detected) were cultured.
The identification of the P250R mutation allowed the confirmation of the Muenke Syndrome in 9 out of the 52 cases referred.
Muenke syndrome, also known as FGFR3-associated coronal synostosis, is defined molecularly by the presence of a heterozygous nucleotide transversion, c.749C>G, encoding the amino acid substitution Pro250Arg, in the fibroblast growth factor receptor type 3 gene (FGFR3).
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