GDF6 Knockdown in a Family with Multiple Synostosis Syndrome and Speech Impairment

Multiple synostoses syndrome type 4 (SYNS4; MIM 617898) is an autosomal dominant disorder characterized by carpal-tarsal coalition and otosclerosis-associated hearing loss. SYSN4 has been associated with GDF6 gain-of-function mutations. Here we report a five-generation SYNS4 family with a reduction in GDF6 expression resulting from a chromosomal breakpoint 3' of GDF6. A 30-year medical history of the family indicated bilateral carpal-tarsal coalition in ~50% of affected family members and acquired otosclerosis-associated hearing loss in females only, whereas vertebral fusion was present in all affected family members, most of whom were speech impaired. All vertebral fusions were acquired postnatally in progressive fashion from a very early age. Thinning across the 2nd cervical vertebral interspace (C2-3) in the proband during infancy progressed to block fusion across C2-7 and T3-7 later in life. Carpal-tarsal coalition and pisiform expansion were bilaterally symmetrical within, but varied greatly between, affected family members. This is the first report of SYNS4 in a family with reduced GDF6 expression indicating a prenatal role for GDF6 in regulating development of the joints of the carpals and tarsals, the pisiform, ears, larynx, mouth and face and an overlapping postnatal role in suppression of aberrant ossification and synostosis of the joints of the inner ear (otosclerosis), larynx and vertebrae. RNAseq gene expression analysis indicated >10 fold knockdown of NOMO3, RBMXL1 and NEIL2 in both primary fibroblast cultures and fresh white blood cells. Together these results provide greater insight into the role of GDF6 in skeletal joint development.

Prenatal diagnosis of Sprengel's deformity in a patient with Klippel-Feil Syndrome

We present a case of Klippel-Feil Syndrome, a congenital skeletal defect where multiple cervical vertebral bodies are fused. Klippel-Feil Syndrome has multiple associated anomalies, with a notable one being Sprengel's deformity. In this case, the patient was given a diagnosis of Klippel-Feil Syndrome prenatally after suspected cervical vertebrae fusion and Sprengel's deformity were seen on both fetal magnetic resonance imaging (MRI) and ultrasound. Prenatal diagnosis of Sprengel's deformity has been reported once in the literature. In this report, we present imaging findings of Sprengel's deformity seen in association with Klippel-Feil Syndrome using a combination of fetal ultrasound and MRI.

Cervical vertebral malformations in 9 dogs: radiological findings, treatment options and outcomes

Background

Disregarding atlantoaxial instability in toy breed dogs associated with dens malformation and cervical spondylomyelopathy; cervical vertebral malformations are rare and poorly characterised in veterinary medicine and consequently treatment strategies and clinical outcome are sparsely documented.

Results

Electronic clinical records at our veterinary referral hospital between April 2009 and November 2018 were searched for patients presented with cervical myelopathy secondary to an underlying suspected vertebral malformation/instability. Nine dogs met the inclusion criteria. Two dogs were diagnosed with atlantoaxial pseudoarthrosis, two dogs with a syndrome similar to Klippel-Feil in humans, two dogs with congenital cervical fusion, two dogs with congenital C2-C3 canal stenosis and deficiencies of the dorsal arch of the atlas and laminae of the axis and one with axial rotatory displacement. Tetraparesis, proprioceptive deficits, cervical hyperesthesia and cervical scoliosis were the most common clinical signs. The axis was the most commonly affected vertebrae (8/9 patients). Patients diagnosed with Klippel-Feil-like Syndrome were the younger (average of 262.5 days) and patients diagnosed with fused vertebrae the oldest (average of 2896 days) in our studied population (average of 1580.8 days).

Conclusion

Cervical vertebral malformations are rare, or alternatively, being underdiagnosed in veterinary medicine. Patients diagnosed with Klippel-Feil-like Syndrome had a successful medium and long-term outcome with conservative management. Surgical treatment was often indicated for the other conditions presented in this study due to spinal instability and/or myelopathy. Stabilisations via ventral approaches were revealed to be safe. Multicentre and prospective studies are necessary in veterinary medicine to better characterise clinical outcomes in cervical vertebral malformations.

Anomalous vertebral arteries in Klippel-Feil syndrome with occipitalized atlas: CT angiography

Klippel-Feil syndrome is an uncommon anomaly that may be asymptomatic. Early clinical signs such as restricted neck motion or short neck can be subtle and incorrectly treated as spasms. High incidence of associated craniovertebral junction (CVJ) anomalies such as occipitalized atlas predisposes them to serious neurologic complications requiring invasive procedures and surgeries. However, these often have anomalous vertebral artery course which is more prone to injury during CVJ procedures, and also sparsely known in radiology literature. We demonstrate the importance of computed tomography angiography in preprocedural planning to avoid catastrophic injury to anomalous vertebral artery at CVJ in such case.

"Clinical triad" findings in pediatric Klippel-Feil patients

BACKGROUND

It has been propagated that patients with Klippel-Feil syndrome (KFS) exhibit "clinical triad" findings (CTFs), known as a short neck, low posterior hairline, and limited cervical range of motion (ROM). However, the literature has noted that up to 50 % of KFS cases may not present with such findings and the reasoning behind such assertions remains speculative. As such, the following study addressed the association between CTFs to that of congenitally-fused cervical segments and other risk factors in KFS patients.

METHODS

We conducted a retrospective clinical study based on prospectively collected radiographic data. Thirty-one KFS patients at a single institution were assessed. Radiographs were used to evaluate the location and extent of congenitally-fused segments (spanning the occiput (O) to the first thoracic vertebra (T1)), as well as examining coronal and sagittal cervical alignments based on the Samartzis et al. KFS classification. Clinical records were evaluated to account for the initial clinical assessment of CTFs. Patients were further stratified into two groups: Group 1 included patients noted to have any CTFs, while Group 2 included patients who had no such findings.

RESULTS

There were 12 males and 19 females (mean age at initial consultation: 9.7 years). No evidence of any of the CTFs was shown in 35.5 % of patients, whereas 38.7, 16.2 and 9.7 % were determined to have one, two or all three criteria, respectively. Limited cervical ROM was the most common finding (64.5 % of patients). In Group 1, 25 % had a short neck, 30 % a low posterior hairline, and 100 % exhibited limited cervical ROM. Group 1 had a mean of 3.9 fused cervical segments, whereas Group 2 had a mean of 2.5 fused cervical segments (p = 0.028). Age, sex-type, occipitalization and alignment parameters did not significantly differ to Group-type (p > 0.05). In Group 1, based on the Samartzis et al. Types I, II, and III, 16.7, 73.3, and 80.0 % of the patients, respectively, had at least one CTF.

CONCLUSIONS

Complete CTFs were not highly associated during the clinical assessment of young KFS patients. However, KFS patients with extensive, congenitally-fused segments (i.e. Samartzis et al. Type III) were significantly more likely to exhibit one of the components of the CTF, which was predominantly a limited cervical ROM. Clinicians managing young pediatric patients should not rely on the full spectrum of CTFs and should maintain a high-index of suspicion for KFS, in particular in individuals that exhibit associated spinal findings, such as congenital scoliosis.

Whole exome sequencing identifies a POLRID mutation segregating in a father and two daughters with findings of Klippel-Feil and Treacher Collins syndromes

We report on a father and his two daughters diagnosed with Klippel-Feil syndrome (KFS) but with craniofacial differences (zygomatic and mandibular hypoplasia and cleft palate) and external ear abnormalities suggestive of Treacher Collins syndrome (TCS). The diagnosis of KFS was favored, given that the neck anomalies were the predominant manifestations, and that the diagnosis predated later recognition of the association between spinal segmentation abnormalities and TCS. Genetic heterogeneity and the rarity of large families with KFS have limited the ability to identify mutations by traditional methods. Whole exome sequencing identified a nonsynonymous mutation in POLR1D (subunit of RNA polymerase I and II): exon2:c.T332C:p.L111P. Mutations in POLR1D are present in about 5% of individuals diagnosed with TCS. We propose that this mutation is causal in this family, suggesting a pathogenetic link between KFS and TCS.

Failure of cervical arthroplasty in a patient with adjacent segment disease associated with Klippel-Feil syndrome

Cervical arthroplasty may be justified in patients with Klippel-Feil syndrome (KFS) in order to preserve cervical motion. The aim of this paper is to report an arthroplasty failure in a patient with KFS. A 36-year-old woman with KFS underwent two-level arthroplasty for adjacent segment disc degeneration. Anterior migration of the cranial prosthesis was encountered 5 months postoperatively and was successfully revised with anterior cervical fusion. Cervical arthroplasty in an extensively stiff and fused neck is challenging and may lead to catastrophic failure. Although motion preservation is desirable in KFS, the special biomechanical features may hinder arthroplasty. Fusion or hybrid constructs may represent more reasonable options, especially when multiple fused segments are present.