A familial case of Muenke syndrome. Diverse expressivity of the FGFR3 Pro252Arg mutation - case report and review of the literature

Muenke is a fibroblast growth factor receptor 3 (FGFR-3)-associated syndrome, which was first described in late 1990s. Muenke syndrome is an autosomal dominant disorder characterized mainly by coronal suture craniosynostosis, hearing impairment and intellectual disability. The syndrome is defined molecularly by a unique point mutation c.749C>G in exon 7 of the FGFR3 gene which results to an amino acid substitution p. Pro250Arg of the protein product. Despite the fact that the mutation rate at this nucleotide is one of the most frequently described in human genome, few Muenke familial case reports are published in current literature. We describe individuals among three generations of a Greek family who are carriers of the same mutation. Medical record and physical examination of family members present a wide spectrum of clinical manifestations. In particular, a 38-year-old woman and her father appear milder clinical findings regarding craniofacial characteristics compared to her uncle and newborn female child. This familial case illustrates the variable expressivity of Muenke syndrome in association with an identical gene mutation

Novel and Gene Mutations With Diverse Phenotypic Features and the Question on the Existence of a Broader Spectrum of Dravet Syndrome

In the light of modern molecular technologies, the understanding of the complexity of the numerous genotype–phenotype correlations regarding Dravet syndrome is mandatory. Motivated by 2 patients, whose whole-exome sequencing revealed novel mutations that exemplify the phenotypic and genetic heterogeneities associated with typical and atypical Dravet syndrome presentations, the authors discuss the existence of a broader spectrum of Dravet syndrome. The first patient is a 4-year-old boy with fairly typical Dravet syndrome and a novel sodium channel α1 subunit gene mutation of high-predicted combined pathogenicity likelihood. The second patient is a 15-year-old boy with some atypical features of Dravet syndrome, harboring a novel mutation of the γ-aminobutyric acid receptor α1 subunit gene, whose role in this syndrome pathogenesis has recently been highlighted. A brief review of the literature reveals that none of the current diagnostic criteria is thoroughly predictive of the disease, and phenotypic discrepancies are common among patients carrying atypical Dravet syndrome mutations. The authors conclude that the discussion of a Dravet syndrome spectrum is relevant