PUF60 loss-of-function with normal cognition should be considered in the differential diagnosis of Klippel-Feil syndrome.

Klippel-Feil syndrome (KFS) has a genetically heterogeneous phenotype with six known genes, exhibiting both autosomal dominant and autosomal recessive inheritance patterns. PUF60 is a nucleic acid-binding protein, which is involved in a number of nuclear processes, including pre-mRNA splicing, apoptosis, and transcription regulation. Pathogenic variants in this gene have been described in Verheij syndrome due to either 8q24.3 microdeletion or PUF60 single-nucleotide variants. PUF60-associated conditions usually include intellectual disability, among other findings, some overlapping KFS; however, PUF60 is not classically referred to as a KFS gene. Here, we describe a 6-year-old female patient with clinically diagnosed KFS and normal cognition, who harbors a heterozygous de novo variant in the PUF60 gene (c.1179del, p.Ile394Serfs*7). This is a novel frameshift variant, which is predicted to result in a premature stop codon. Clinically, our patient demonstrates a pattern of malformations that matches reported cases of PUF60 variants; however, unlike most others, she has no clear learning difficulties. In light of these findings, we propose that PUF60 should be considered in the differential diagnosis of KFS and that normal cognition should not exclude its testing.

Chiari type III malformation associated with Klippel-Feil syndrome, a case report with a narrative review of the literature.

BACKGROUND: Chiari malformation type III (CM III), a rare hindbrain anomaly, often presents with various concurrent anomalies. This paper reports a unique case of CM III associated with Klippel-Feil syndrome (KFS), a condition previously unreported in Saudi Arabia and documented in only one other case globally in Turkey. This study aims to share insights into the unusual association between CM III and KFS, considering their close embryological development and involvement in the craniocervical junction. METHODOLOGY: The study presents a case of a 2.5-year-old female diagnosed with CM III and KFS. Diagnostic tools such as ultrasound, CT scans, MRI, and physical examinations were used to confirm the patient's condition. Surgical interventions, including decompression and encephalocele repair, were performed. RESULTS: Successful surgical interventions, including encephalocele repair and duraplasty, were carried out. Follow-up visits indicated a stable condition, marked improvement in lower limb strength, and the patient's ability to walk with assistance. CT follow-up affirmed a satisfactory surgical outcome. CONCLUSION: This case study illustrates the potential for an optimistic prognosis in CM III, even when accompanied by complex conditions such as KFS, through early diagnosis and intervention. It underscores the significance of antenatal screening for effective care planning and calls for further research and publications due to the rarity of this association. These findings contribute to our understanding of CM III and its related conditions, emphasizing the need for open-minded consideration of potential embryological associations.

Klippel-Feil syndrome: Should additional examination be conducted?

PURPOSE: Klippel-Feil syndrome (KF) is a rare disease defined as single or multi-level cervical vertebra fusion. KF could be accompanied by other spinal anomalies or isolated, and in which case necessity of whole spine screening is not clearly known. KF is investigated in terms of prevalence, gender distribution, fusion types, and frequency of accompanying anomalies according to types of KF. METHODS: Approval from our hospital's ethics committee was received for this single-center, retrospective study. Considering the exclusion criteria among the 40,901 cervical spine MRIs, 40,450 patients were included in the study. It was re-evaluated for KF, fusion level, classification, cervical scoliosis, and other musculoskeletal and spinal anomalies. RESULTS: 125 (0.309%) of 40,450 patients is diagnosed with KF, which is more common in women (P < 0.001). Single fused segment 106 (84.8%), multilevel fused segments 8 (6.4%), contiguous fused segments 11 (8.8%) are observed. Upper level KF is detected in 13 (10.4%) patients. The frequency of additional anomaly is significantly higher in upper level KF compared to other level fusions (P < 0.001, Chi-square t). The cervical scoliosis is diagnosed 34 (27%). In KF patients with scoliosis, the frequency of additional anomalies was significantly higher (P < 0.001, Chi-square t). CONCLUSION: Klippel-Feil prevalence is 0.309%, it is frequently observed in women, and at C2-C3 level. Additional anomalies are especially associated with 'contiguous fused segments' and 'upper level' types. Klippel-Feil with scoliosis is an indicator of increased risk for associated anomalies, and examination of the whole spine is recommended.

Cervical split cord malformation (diastematomyelia) with associated Klippel-Feil deformity presenting in adulthood with bimanual synkinesis.

BACKGROUND: Split cord malformation (SCM) is a rare congenital malformation of the spinal cord in which the cord is split longitudinally. Identification and diagnosis in adulthood is rare, with the majority of cases diagnosed in the paediatric population. Isolated segmental cervical SCM is rarer still. CASE PRESENTATION: Here, the authors present the case of a 26-year-old female who presented with neck pain and longstanding bimanual synkinesis secondary to an isolated type II SCM in the C4-C7 region. The authors present this novel presenting symptom in adulthood and finding of isolated cervical SCM with associated blocked cervical vertebrae, in an otherwise normal neuroaxis and spinal column. CONCLUSIONS: The case serves to highlight the importance of knowledge of this rare congenital condition to surgeons, physicians and radiologists involved in the care of both adult and paediatric patients presenting with spinal pathology.

[The multisystem deformities features of Klippel-Feil syndrome patients combined with congenital scoliosis].

Objective: To summarize the characteristics of multisystem deformities in patients with Klippel-Feil syndrome (KFS) combined with congenital scoliosis (CS). Methods: Within the framework of the "Deciphering Disorders Involving Scoliosis and Comorbidities (DISCO)" research collaboration, a retrospective analysis was conducted on patients diagnosed with KFS and CS at Peking Union Medical College Hospital between April 2005 and August 2022. Patient data, including imaging examinations and medical records, were collected to summarize the spinal and associated deformities. Results: A total of 82 KFS patients with concurrent CS were included, comprising 42 males and 40 females. The average age was (12.8±8.9) years. Among the KFS patients, there were 31 cases of Type Ⅰ, 12 cases of Type Ⅱ, and 39 cases of Type Ⅲ. The most common location for the major curve of scoliosis was the mid-thoracic segment (42 cases, 51.2%). Hemivertebrae deformities were most frequently observed in the upper thoracic segment (31 cases, 60.8%). There were no statistically significant differences in age, gender, major curve Cobb angle, or region of hemivertebrae occurrence among the different types of KFS (all P>0.05). Apart from spinal vertebral deformities, intraspinal deformities had the highest comorbidity rate (33 cases, 40.2%). The subjects were divided into two groups based on the presence or absence of intraspinal deformity (absence as group G0, presence as group G1), there was a statistically significant difference in the main Cobb angle [M(Q1, Q3)] between the two groups, which was 45.0° (27.5°, 62.0°) and 60.0° (37.5°, 83.5°), respectively (P=0.044). Additionally, a portion of the patients had concurrent cardiovascular system abnormalities (13 cases, 15.9%), craniofacial-ocular-auricular abnormalities (8 cases, 9.8%), genitourinary system abnormalities (7 cases, 8.5%), and gastrointestinal abnormalities (2 cases, 2.4%). Conclusions: Patients with KFS combined with CS commonly present with a major curve of spinal deformity in the mid-thoracic segment and often have comorbidities involving multiple systems. When combined with intraspinal anomalies, the major curve exhibits a greater degree of curvature.

A Novel Technique for Basilar Invagination Treatment in a Patient with Klippel-Feil Syndrome: A Clinical Example and Brief Literature Review.

Objectives and Background: To present a novel technique of treatment for a patient with basilar invagination. Basilar invagination (BI) is a congenital condition that can compress the cervicomedullary junction, leading to neurological deficits. Severe cases require surgical intervention, but there is debate over the choice of approach. The anterior approach allows direct decompression but carries high complication rates, while the posterior approach provides indirect decompression and offers good stability with fewer complications. Materials and Methods: A 15-year-old boy with severe myelopathy presented to our hospital with neck pain, bilateral upper limb muscle weakness, and hand numbness persisting for 4 years. Additionally, he experienced increased numbness and gait disturbance three months before his visit. On examination, he exhibited hyperreflexia in both upper and lower limbs, muscle weakness in the bilateral upper limbs (MMT 4), bilateral hypoesthesia below the elbow and in both legs, mild urinary and bowel incontinence, and a spastic gait. Radiographs revealed severe basilar invagination (BI). Preoperative images showed severe BI and that the spinal cord was severely compressed with odontoid process. Results: The patient underwent posterior surgery with the C-arm free technique. All screws including occipital screws were inserted into the adequate position under navigation guidance. Reduction was achieved with skull rotation and distraction. A follow-up at one year showed the following results: Manual muscle testing results and sensory function tests showed almost full recovery, with bilateral arm recovery (MMT 5) and smooth walking. The cervical Japanese Orthopedic Association score of the patient improved from 9/17 to 16/17. Postoperative images showed excellent spinal cord decompression, and no major or severe complications had occurred. Conclusions: Basilar invagination alongside Klippel-Feil syndrome represents a relatively uncommon condition. Utilizing a posterior approach for treating reducible BI with a C-arm-free technique proved to be a safe method in addressing severe myelopathy. This novel navigation technique yields excellent outcomes for patients with BI.

Posterior Occipitocervical Fixation and Intrathecal Baclofen Therapy for the Treatment of Basilar Invagination with Klippel-Feil Syndrome: A Case Report.

Klippel-Feil syndrome (KFS) is characterized by the congenital fusion of the cervical vertebrae and is sometimes accompanied by anomalies in the craniocervical junction. In basilar invagination (BI), which is a dislocation of the dens in an upper direction, compression of the brainstem and cervical cord results in neurological defects and surgery is required. A 16-year-old boy diagnosed with KFS and severe BI presented with spastic tetraplegia, opisthotonus and dyspnea. CT scans showed basilar impression, occipitalization of C1 and fusion of C2/C3. MRI showed ventral compression of the medullocervical junction. Posterior occipitocervical reduction and fusion along with decompression were performed. Paralysis gradually improved postoperatively over 3 weeks. However, severe spasticity and opisthotonus persisted and intrathecal baclofen (ITB) therapy was initiated. Following this, opisthotonus disappeared and spasticity of the extremities improved. Rehabilitation therapy continued by controlling the dose of ITB. Five years after the surgery, self-propelled wheelchair driving was achieved and activities of daily life improved. The treatment strategy for patients with BI and congenital anomalies remains controversial. Posterior reduction and internal fixation using instrumentation were effective techniques in this case. Spasticity control achieved through a combination of surgery and ITB treatment enabled the amelioration of therapeutic efficacy of rehabilitation and the improvement of ADL.

Evolving Concepts of Craniovertebral and Spinal Instability.

Weakness of the muscles of the nape of the neck and back of the spine and its related instability is the nodal point of pathogenesis of a number of clinical and pathological events at the craniovertebral junction and the spine. Whilst acute instability results in sudden and relatively severe symptoms, chronic or long-standing instability is associated with a range of musculoskeletal and structural spinal alterations. Telescoping of the spinal segments results in "vertical" spinal instability in the subaxial spine and central or axial atlantoaxial instability (CAAD) at the craniovertebral junction. Instability in such cases might not be observed on dynamic radiological imaging. Chiari formation, basilar invagination, syringomyelia, and Klippel-Feil alteration are some of the secondary alterations as a result of chronic atlantoaxial instability. Radiculopathy/myelopathy related to spinal degeneration or ossification of posterior longitudinal ligament appears to have their origin from vertical spinal instability. All the secondary alterations in the craniovertebral junction and subaxial spine that are traditionally considered pathological and to have compressive and deforming role are essentially protective in nature, are indicative of instability, and are potentially reversible following atlantoaxial stabilization. Stabilization of unstable spinal segments is the basis of surgical treatment.

Brown Sequard syndrome in a patient with Klippel-Feil syndrome following minor trauma: a case report and literature review.

BACKGROUND: There are some cases of Klippel-Feil syndrome with spinal cord injury in clinical work. However, there is no literature report on Brown-Sequard syndrome after trauma. We report a case of Brown-Sequard syndrome following minor trauma in a patient with KFS type III. Her Brown-Sequard syndrome is caused by Klippel-Feil syndrome. CASE PRESENTATION: We found a 38-year-old female patient with KFS in our clinical work. She was unconscious on the spot following a minor traumatic episode. After treatment, her whole body was numb and limb activity was limited. Half an hour later, she felt numb and weak in the right limb and weak in the left limb. She had no previous hypertension, diabetes, or coronary heart disease. After one-month treatment of medication, hyperbaric oxygen, rehabilitation, and acupuncture in our hospital, her muscle strength partially recovered, but the treatment effect was still not satisfactory. Then, she underwent surgical treatment and postoperative comprehensive treatment, and rehabilitation training. She was able to take care of herself with assistance, and her condition improved from grade B to grade D according to the ASIA (ASIA Impairment Scale) classification. CONCLUSION: KFS, also known as short neck deformity, is a kind of congenital deformity characterized by impaired formation and faulty segmentation of the cervical spine, often associated with abnormalities of other organs. The cervical deformity in patients with KFS can alter the overall mechanical activity of the spine, as well as the compensatory properties of the spine for decelerating and rotatory forces, thus increasing the chance of spinal cord injury (SCI) following trauma. Many mechanisms can make patients more susceptible to injury. Increased range of motion of the segment adjacent to the fused vertebral body may lead to slippage of the adjacent vertebral body and altered disc stress, as well as cervical instability. SCI can result in complete or incomplete impairment of motor, sensory and autonomic nervous functions below the level of lesion. This woman presented with symptoms of BSS, a rare neurological disorder with incomplete SCI. Judging from the woman's symptoms, we concluded that previously she had KFS, which resulted in SCI without fracture and dislocation following minor trauma, with partial BSS. After the comprehensive treatment of surgery, hyperbaric oxygen, rehabilitation therapy, and neurotrophic drugs, two years later, we found her symptoms significantly improved, with ASIA Impairment Scale from grade B to grade D, and her ability to perform activities of daily living with aids.

The predictive ability of occipital to C3 angle for dysphagia after occipitocervical fusion in patients with combined C2-3 Klippel-Feil syndrome.

BACKGROUND: Improper occipitocervical alignment after occipitocervical fusion (OCF) may lead to devastating complications, such as dysphagia and/or dyspnea. The occipital to C2 angle (O-C2a), occipital and external acoustic meatus to axis angle (O-EAa) have been used to evaluate occipitospinal alignment. However, it may be difficult to identify the inferior endplate of the C2 vertebra in patients with C2-3 Klippel-Feil syndrome (KFS). The purpose of this study aimed to compare four different parameters for predicting dysphagia after OCF in patients with C2-3 KFS. METHODS: There were 40 patients with C2-3 KFS undergoing OCF between 2010 and 2019. Radiographs of these patients were collected to measure the occipital to C3 angle (O-C3a), O-C2a, occipito-odontoid angle (O-Da), occipital to axial angle (Oc-Axa), and narrowest oropharyngeal airway space (nPAS). The presence of dysphagia was defined as the patient complaining of difficulty or excess endeavor to swallow. Patients were divided into two groups according to whether they had postoperative dysphagia. We evaluated the relationship between each of the angle parameters and nPAS and analyzed their influence to the postoperative dysphagia. RESULTS: The incidence of dysphagia after OCF was 25% in patients with C2-3 KFS. The Oc-Axa, and nPAS were smaller in the dysphagia group compared to non-dysphagia group at the final follow-up (p < 0.05). Receiver-operating characteristic (ROC) curves showed that dO-C3a had the highest accuracy as a predictor of the dysphagia with an area under the curve (AUC) of 0.868. The differences in O-C3a, O-C2a, O-Da, and Oc-Axa were all linearly correlated with nPAS scores preoperatively and at the final follow-up within C2-3 KFS patients, while there was a higher R2 value between the dO-C3a and dnPAS. Multiple linear regression analysis showed that the difference of O-C3a was the only significant predictor for dnPAS (ß = 0.670, p < 0.001). CONCLUSIONS: The change of O-C3a (dO-C3a) is the most reliable indicator for evaluating occipitocervical alignment and predicting postoperative dysphagia in C2-3 KFS patients. Moreover, dO-C3a should be more than - 2° during OCF to reduce the occurrence of postoperative dysphagia.

A case of ischemic stroke accompanied by multiple arterial dissections associated with Klippel-Feil syndrome.

OBJECTIVES: To describe the case of an ischemic stroke patient with Klippel-Feil syndrome who developed multiple aneurysms and discuss the mechanism of aneurysm development. MATERIALS AND METHODS: A 44-year-old man presented with dizziness, left hemiparesis, and left-sided numbness and was admitted to our department. He developed multiple aneurysms at the bilateral vertebral artery (VA) and bilateral internal carotid artery. RESULTS: We diagnosed the etiology of his brain infarction as an embolic stroke caused by left VA dissection or the large thrombosed aneurysm. Furthermore, we considered that arterial dissection or Hox gene mutation was associated with the development of multiple aneurysms. CONCLUSION: While previous reports have described single aneurysm, this is the first report of multiple aneurysms associated with Klippel-Feil syndrome.

Further delineation of MYO18B-related autosomal recessive Klippel-Feil syndrome with myopathy and facial dysmorphism.

Klippel-Feil syndrome 4 (KFS4; MIM# 616549) is an autosomal recessive disorder caused by biallelic pathogenic variants in MYO18B and comprises, in addition to Klippel-Feil anomaly (KFA), nemaline myopathy, facial dysmorphism, and short stature. We aim to outline the natural history of KFS4 and provide an updated description of its clinical, radiological, laboratory, and molecular findings. We comprehensively analyzed the medical records of 6 Saudi and 1 American patients (including 5 previously unpublished cases) with a molecularly confirmed diagnosis of KFS4. All patients had myopathy of varying severity that followed a slowly progressive or non-progressive course, affecting primarily the proximal musculature of the lower limb although hand involvement with distal arthrogryposis and abnormal interphalangeal creases was also observed. KFA and characteristic dysmorphic features, including ptosis and bulbous nose, were observed in all but two patients. The causal MYO18B variants were a founder NM_032608.5:c.6905C>A; p.(Ser2302*) variant in the Saudi patients (P1-P6) and a novel MYO18B homozygous variant (c.6660_6670del;p.[Arg2220Serfs*74]) in the American Caucasian patient (P7). We report the phenotypic and genetic findings in seven patients with KFS4. We describe the natural history of this disease, confirm myopathy as a universal feature and describe its pattern and progression, and note interesting differences between the phenotypes observed in patients with KFA and those without.

Detailed clinical and radiological features of the first patient with Elsahy-Waters syndrome in East Asia.

Elsahy-Waters syndrome (EWS; OMIM#211380) is a rare autosomal recessive disorder that is caused by loss-of-function variants in CDH11, which encodes cadherin 11. EWS is characterized by brachycephaly, midface hypoplasia, characteristic craniofacial morphology, cervical fusion, cutaneous syndactyly in 2-3 digits, genitourinary anomalies, and intellectual disability. To the best of our knowledge, there have been only six patients of molecularly confirmed EWS. We report the first patient of EWS in East Asia in a Japanese man with a novel splice site homozygous variant of CDH11. We reviewed the clinical and molecular findings in previously reported individuals and the present patient. In addition to the previously reported clinical features of EWS, the present patient had unreported findings of atlantoaxial instability due to posterior displacement of dens, thoracic fusion, thoracic butterfly vertebra, sacralization of the lumbar vertebra (L5), and multiple perineural cysts. The spinal findings in this patient could represent a new spectrum of skeletal phenotypes of EWS. It remains to be clarified whether the multiple perineural cysts in the patient were associated with EWS or coincidental. The current observation might contribute to an expanded understanding of the clinical consequences of loss-of-function of cadherin 11.

A rare case of difficult airway management in a Klippel-Feil syndrome pediatric patient with osseous torticollis undergone orthopedic surgery : Difficult airway in pediatric patient with torticollis.

BACKGROUND: Orthopedic surgery for cervical torticollis poses potential threat to airway management both in tracheal intubation and extubation. Klippel-Feil syndrome (KFS) is a complex syndrome of osseous and visceral anomalies. The anatomical characteristics of KFS might have significant implications for airway management. CASE PRESENTATION: This is a rare case of an 8-year-old boy presenting with osseous torticollis, congenital occipito-atlantal deformity, congenital basilar invagination and KFS undergone elective torticollis correction surgery. Though with difficulty, tracheal intubation was successfully performed. Extubation failed twice on postoperative day 2 and 10, and required tracheostomy. Based on radiological findings, we speculated that prolonged airway edema accounted for the main reason of the failed extubation, the hypertrophic tonsil and occipito-cervical fusion resulted in reduced oropharyngeal space and limited cervical range of motion. Moreover, the Chiari malformation and KFS complicated the airway condition and lead to prolonged airway obstruction. The tracheostomy casing was removed 1 month later. CONCLUSIONS: Cautions should be taken in extubation of pediatric patients undergone major osseous torticollis surgery. Reintubation should be prepared in case of failed extubation. Severe post-operative airway edema, complicated with hypertrophic tonsil, the structural abnormalities in the oropharyngeal cavity, and occipito-cervical deformities constituted the decreased oropharyngeal space and resulted in failed extubation. For severe airway compromise and prolonged intubation, tracheostomy should be considered.

[Clinical Characteristics and Genetic Analysis of Klippel-Feil Syndrome].

Objective To summarize clinical characteristics and investigate possible pathogenic gene of Klippel-Feil syndrome(KFS)by the self-designed multigene panel sequencing,so as to decipher the molecular basis for early diagnosis and targeted therapy.Methods From January 2015 to December 2018,we consecutively recruited 25 patients who were diagnosed with KFS in Peking Union Medical College Hospital.The demographic information,clinical manifestations,physical examination and radiological assessments were analyzed.Multigene panel sequencing was performed after DNA extraction from peripheral blood.The possible pathogenic mutations of KFS were explored on the basis of bioinformatics analysis.Results The KFS cohort consisted of 25 patients,including 15 males and 10 females,with a mean age of(12.9±7.3)years.Limited cervical range of motion was the most common clinical feature(12 cases,48%).Based on the Samartzis classification,the proportion of patients suffered from short neck(P=0.031)and limited cervical range of motion(P=0.026)in type Ⅲ KFS was significantly higher than that in type Ⅱ and type Ⅰ KFS.Panel sequencing detected a total of 11 pathogenic missense mutations in eight patients,including COL6A1,COL6A2,CDAN1,GLI3,FLNB,CHRNG,MYH3,POR,and TNXB.There was no pathogenic mutation found in five reported pathogenic genes(GDF6,MEOX1,GDF3,MYO18B and RIPPLY2)associated with KFS.Conclusions Our study has shown that patients with multiple contiguous cervical fusions are more likely to manifest short neck,limited cervical range of motion,and clinical triad.Therefore,these patients need additional attention and follow-up.Our analysis highlights novel KFS-related genetic variants,such as COL6A and CDAN1,extending the spectrum of known mutations contributing to this syndrome and providing a basis for elucidating the pathogenesis of KFS.

Congenital posterior cervical spine malformation due to biallelic c.240-4T>G RIPPLY2 variant: A discrete entity.

The clinical and radiological spectrum of spondylocostal dysostosis syndromes encompasses distinctive costo-vertebral anomalies. RIPPLY2 biallelic pathogenic variants were described in two distinct cervical spine malformation syndromes: Klippel-Feil syndrome and posterior cervical spine malformation. RIPPLY2 is involved in the determination of rostro-caudal polarity and somite patterning during development. To date, only four cases have been reported. The current report aims at further delineating the posterior malformation in three new patients. Three patients from two unrelated families underwent clinical and radiological examination through X-ray, 3D computed tomography and brain magnetic resonance imaging. After informed consent was obtained, family-based whole exome sequencing (WES) was performed. Complex vertebral segmentation defects in the cervico-thoracic spine were observed in all patients. WES led to the identification of the homozygous splicing variant c.240-4T>G in all subjects. This variant is predicted to result in aberrant splicing of Exon 4. The current report highlights a subtype of cervical spine malformation with major atlo-axoidal malformation compromising spinal cord integrity. This distinctive mutation-specific pattern of malformation differs from Klippel-Feil syndrome and broadens the current classification, defining a sub-type of RIPPLY2-related skeletal disorder. Of note, the phenotype of one patient overlaps with oculo-auriculo-vertebral spectrum disorder.

The mutational burden and oligogenic inheritance in Klippel-Feil syndrome.

BACKGROUND: Klippel-Feil syndrome (KFS) represents a rare anomaly characterized by congenital fusion of the cervical vertebrae. The underlying molecular etiology remains largely unknown because of the genetic and phenotypic heterogeneity. METHODS: We consecutively recruited a Chinese cohort of 37 patients with KFS. The clinical manifestations and radiological assessments were analyzed and whole-exome sequencing (WES) was performed. Additionally, rare variants in KFS cases and controls were compared using genetic burden analysis. RESULTS: We primarily examined rare variants in five reported genes (GDF6, MEOX1, GDF3, MYO18B and RIPPLY2) associated with KFS and detected three variants of uncertain significance in MYO18B. Based on rare variant burden analysis of 96 candidate genes related to vertebral segmentation defects, we identified BAZ1B as having the highest probability of association with KFS, followed by FREM2, SUFU, VANGL1 and KMT2D. In addition, seven patients were proposed to show potential oligogenic inheritance involving more than one variants in candidate genes, the frequency of which was significantly higher than that in the in-house controls. CONCLUSIONS: Our study presents an exome-sequenced cohort and identifies five novel genes potentially associated with KFS, extending the spectrum of known mutations contributing to this syndrome. Furthermore, the genetic burden analysis provides further evidence for potential oligogenic inheritance of KFS.

Intrathoracic bifurcation of the left common carotid artery associated with rib fusion and Klippel-Feil syndrome.

Common carotid artery usually bifurcates at the superior border of thyroid cartilage, corresponding to the C3-4 junction, however bifurcation level may vary. Common carotid bifurcation may have rare variations like separate origins of left internal and external carotid arteries from aortic arch, or bifurcation of common carotid artery within thoracic cavity. Intrathoracic carotid bifurcation is a rare variation with limited number of cases reported. The occurrence of a low carotid bifurcation seems to be embryologically related to the persistence of the ductus caroticus. Additionally, intrathoracic carotid bifurcation can be accompanied by findings of Klippel-Feil syndrome. Herein, we present imaging findings of an incidentally detected intrathoracic left common carotid artery bifurcation in a pediatric patient accompanied by fusion of the cervical vertebrae and ribs.

Klippel-Feil syndrome misdiagnosed as spondyloarthropathy: case-based review.

Spondyloarthropathy refers to any joint disease of the vertebral column, but the term is mainly used for a specific group of disorders called seronegative spondyloarthropathies (SpAs). The axial skeletal involvement, peripheral and extra-articular manifestations and an association with the major histocompatibility complex class I human leukocyte antigen-B27 (HLA B27) are commonly shared features of SpAs. Klippel-Feil syndrome (KFS) is a rare congenital disorder characterized by the fusion of one or more cervical vertebrae, accompanied by various skeletal and extra-skeletal anomalies. We report a case of an adult male patient with HLA B27 positivity presenting with chronic cervical spine pain accompanied by morning stiffness and periodic night pain, with radiologically confirmed ankylosis and fusion of several cervical segments. His medical history included urogenital abnormalities operated in childhood and mild mitral prolapse. Initially suspected diagnosis of an early axial form of SpA was rejected after thorough workup. Instead, the nature of vertebral defects along with the past medical history of urogenital and cardiac abnormalities pointed towards the diagnosis of KFS. HLA B27 presence can be a confounder in patients presenting with spinal pain and that is why the differential diagnosis of CSD-s and SpA can be challenging in some patients.

Klippel-Feil syndrome: A very unusual cause of severe aortic regurgitation visualized by multimodality imaging.

A 51-year-old man with Klippel-Feil syndrome (KFS) and immunodeficiency syndrome, status postintravenous immunoglobulin therapy, presented with shortness of breath. He was found to have severe aortic regurgitation in the setting of a trileaflet aortic valve with thickened leaflets and mild prolapse of the right coronary cusp with left ventricular dilation and borderline left ventricular ejection fraction. Although various cardiac anomalies have been described in KPS, otherwise unexplained severe aortic regurgitation has not been previously reported to the best of our knowledge. The patient underwent an uncomplicated surgical aortic valve replacement with a 25-mm Medtronic Avalus pericardial tissue valve resulting in symptomatic improvement. Intra-operative management and transesophageal echocardiography can be particularly challenging in KFS patients. We describe the first reported case of severe aortic regurgitation in KPS, review the cardiac anomalies associated with the syndrome, and highlight the clinical challenges in intra-operative management of these patients.