The feet in Pfeiffer's syndrome

Familial Pfeiffer Syndrome: Variable Manifestations and Role of Multidisciplinary Team Care

Pfeiffer syndrome is one of the autosomal dominant craniofacial syndromes. Classical clinical manifestations are coronal suture synostosis causing brachycephaly, midface retrusion, airway compromise, broad thumbs, and toes. Pfeiffer syndrome type I (classic type) is associated with FGFR1 mutation. However, wide range of clinical manifestations, with and without craniosynostosis, have been reported. Here, we present a family of Pfeiffer syndrome across 3 generations with identical FGFR1: c.755C>G (p.Pro252Arg) mutation. Where the members of the youngest generation have no cranial involvement. Lastly, we propose a guideline management for familial Pfeiffer syndrome management.

Minimally Invasive Hallux Interphalangeal Joint Arthrodesis for Hallux Varus in Pfeiffer Syndrome: A Case Report

Pfeiffer syndrome is a rare hereditary condition with an autosomal dominant transmission caused by a mutation that affects fibroblast growth factor receptors. It is one of the acrocephalosyndactyly diseases causing cranial malformations owing to early suture fusion. In the foot, it is typically associated with hallux varus, first ray hyperplasia, and partial lesser digit syndactyly. We report a clinical case of a 10-year-old patient with Pfeiffer type I syndrome with bilateral severe hallux varus due to a hypoplastic trapezoidal shaped proximal phalanx, a distal, medial-facing articular surface, and interphalangeal instability. This deformity was addressed by minimally invasive hallux interphalangeal joint arthrodesis with internal and external fixation. We report the results at the 2-year follow-up point.

Upper extremity anomalies in Pfeiffer syndrome and mutational correlations

BACKGROUND

Pfeiffer syndrome is characterized by craniosynostosis and a variety of associated upper and lower extremity anomalies. The authors reviewed presentation and treatment of upper extremity anomalies in a series of genotyped patients with Pfeiffer syndrome.

METHODS

Medical records of patients with Pfeiffer syndrome seen at the authors' institution over a 16-year period were reviewed. Data on clinical presentation, genetic testing, and treatment were collected. The upper extremity anomalies were documented using plain radiographs and physical examinations by a multidisciplinary craniofacial team.

RESULTS

Of 15 patients identified as having FGFR1- or FGFR2-confirmed Pfeiffer syndrome, 12 (80 percent) presented with upper extremity anomalies, most commonly broad thumbs [n = 10 (83 percent)], radial clinodactyly (thumbs) [n = 7 (58 percent)], and symphalangism [n = 7 each (58 percent)]. All patients with upper extremity anomalies had lower extremity anomalies. Six of the 12 patients (50 percent) with upper extremity findings underwent surgical correction. FGFR1 or FGFR2 genotype did not correlate with upper extremity phenotype.

CONCLUSIONS

Although broad thumbs are common, patients with Pfeiffer syndrome often present with other upper extremity anomalies that may not require surgical intervention. Genetic and allelic heterogeneity may explain phenotypic variability in these upper extremity anomalies. Characterization of these limb differences should be made by pediatric hand surgeons as part of a craniofacial team. Treatment decisions should be individualized and dictated by the type and severity of clinical presentation.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Risk, IV.

Talocalcaneal coalition in Muenke syndrome: report of a patient, review of the literature in FGFR-related craniosynostoses, and consideration of mechanism

Muenke syndrome is an autosomal dominant craniosynostosis syndrome resulting from a defining point mutation in the Fibroblast Growth Factor Receptor3 (FGFR3) gene. Muenke syndrome is characterized by coronal craniosynostosis (bilateral more often than unilateral), hearing loss, developmental delay, and carpal and/or tarsal bone coalition. Tarsal coalition is a distinct feature of Muenke syndrome and has been reported since the initial description of the disorder in the 1990s. Although talocalcaneal coalition is the most common tarsal coalition in the general population, it has never previously been reported in a patient with Muenke syndrome. We present a 7-year-old female patient with Muenke syndrome and symptomatic talocalcaneal coalition. She presented at the age of 7 with limping, tenderness and pain in her right foot following a fall and strain of her right foot. She was treated with ibuprofen, shoe inserts, a CAM walker boot, and stretching exercises without much improvement in symptoms. A computed tomography (CT) scan revealed bilateral talocalcaneal coalitions involving the middle facet. She underwent resection of the talocalcaneal coalitions, remaining pain-free post-operatively with an improvement in her range of motion, gait, and mobility. This report expands the phenotype of tarsal coalition in Muenke syndrome to include talocalcaneal coalition. A literature review revealed a high incidence of tarsal coalition in all FGFR related craniosynostosis syndromes when compared to the general population, a difference that is statistically significant. The most common articulation involved in all syndromic craniosynostoses associated with FGFR mutations is the calcaneocuboid articulation.

Advances in the molecular pathogenesis of craniofacial conditions

The impact that the understanding of fibroblast growth factor receptor (FGFR) biology and its relevance to the pathogenesis of the craniosynostoses has made cannot be underestimated. As the genetic and molecular pathology of other conditions become increasingly understood, there is much hope that robust and relevant animal models of these conditions may be generated. From these models-and in conjunction with laboratory studies in vitro-comes a real hope of improved therapeutic strategies. The future lies in increased cooperation between clinicians working in high-volume centers and basic scientists. This article decribes the results of a decade of research in which the molecular pathology of the craniosynostoses was unravelled. The understanding of the importance of FGFR mutations to the genetic etiology of craniosynostosis opened up novel studies in developmental biology in various tissues. Such studies describe the functional effects of FGFR mutations. Investigations of FGFR expression in human craniofacial development have related functional molecular studies to human craniosynostosis syndromes, which provides a link between the gene mutation and the affected child.

De novo alu-element insertions in FGFR2 identify a distinct pathological basis for Apert syndrome

Apert syndrome, one of five craniosynostosis syndromes caused by allelic mutations of fibroblast growth-factor receptor 2 (FGFR2), is characterized by symmetrical bony syndactyly of the hands and feet. We have analyzed 260 unrelated patients, all but 2 of whom have missense mutations in exon 7, which affect a dipeptide in the linker region between the second and third immunoglobulin-like domains. Hence, the molecular mechanism of Apert syndrome is exquisitely specific. FGFR2 mutations in the remaining two patients are distinct in position and nature. Surprisingly, each patient harbors an Alu-element insertion of approximately 360 bp, in one case just upstream of exon 9 and in the other case within exon 9 itself. The insertions are likely to be pathological, because they have arisen de novo; in both cases this occurred on the paternal chromosome. FGFR2 is present in alternatively spliced isoforms characterized by either the IIIb (exon 8) or IIIc (exon 9) domains (keratinocyte growth-factor receptor [KGFR] and bacterially expressed kinase, respectively), which are differentially expressed in mouse limbs on embryonic day 13. Splicing of exon 9 was examined in RNA extracted from fibroblasts and keratinocytes from one patient with an Alu insertion and two patients with Pfeiffer syndrome who had nucleotide substitutions of the exon 9 acceptor splice site. Ectopic expression of KGFR in the fibroblast lines correlated with the severity of limb abnormalities. This provides the first genetic evidence that signaling through KGFR causes syndactyly in Apert syndrome.