Five new consanguineous families with horizontal gaze palsy and progressive scoliosis and novel ROBO3 mutations

Horizontal Gaze Palsy with Progressive Scoliosis with Overlapping Epilepsy and Learning Difficulties: A Case Report

Horizontal gaze palsy with progressive scoliosis (HGPPS) is a rare congenital disease characterized by the absence of horizontal gaze movements, progressive scoliosis, and typical brain, cerebellum, and medullary malformations. Here we describe a pediatric HGPPS case with overlapping epilepsy and learning difficulties. A 6-year-old girl was admitted to the University Hospital of Bari for the onset of a tonic–clonic seizure. Electroencephalogram showed slow and sharp waves on the right side with the tendency to diffuse. Brain magnetic resonance imaging demonstrated malformations compatible with HGPPS. Ophthalmological and orthopedic evaluations confirmed conjugate horizontal gaze palsy and mild thoracolumbar scoliosis. Neuropsychological assessment attested normal intelligence but serious difficulties in reading and writing. In spite of neuroradiological malformations, visual difficulties, and spinal deformities, literature data are limited about any coexisting neurocognitive HGPPS symptoms. Literature data regarding such topics are very limited. If, on the one hand, the coexistence of such symptoms can be interpreted as occasional, it could support the idea that they could fall within a spectrum of HGPPS anomalies. In addition to the standard investigations, the activation of specific neuropsychological assessment programs could help interventions improve the specialist care and the quality of life of HGPPS patients.

Compound Heterozygous ROBO3 Mutation in Two Siblings Presenting with Horizontal Gaze Palsy without Scoliosis: Case-Based Review

Horizontal gaze palsy with progressive scoliosis (HGPPS) is a rare, autosomal recessively inherited disorder characterized by a congenital absence of conjugated horizontal eye movements with progressive scoliosis developing in childhood and adolescence. HGPPS is caused by mutations of the ROBO3 gene that disrupts the midline crossing of the descending corticospinal and ascending lemniscal sensory tracts in the medulla. We present two siblings, 5-year-old and 2-year-old boys with HGPPS, from non-consanguineous parents. The older brother was brought for the evaluation of moderate psychomotor retardation. He had bilateral horizontal gaze palsy with preserved vertical gaze and convergence. Scoliosis was absent. Cranial MRI showed brainstem abnormalities, and diffusion tensor imaging showed absent decussation of cortico-spinal tracts in the medulla. Clinical diagnosis of HGPPS was confirmed by sequencing of ROBO3 gene, IVS4–1G > A (c.767–1G > A) and c.328_329delinsCCC (p.Asp110Profs*57) compound heterozygous variations were found, and segregated in parents. The younger boy was first reported at 16 months of age and had the same clinical and neuroradiological findings, unlike mild psychomotor retardation. ROBO3 gene analysis showed the same variants in his brother. Our cases show the importance of evaluating eye movements in children with neurodevelopmental abnormalities and looking for brainstem abnormalities in children with bilateral horizontal gaze palsy.

Uncrossed corticospinal tract in health and genetic disorders: Review, case report, and clinical implications

BACKGROUND AND PURPOSE

Crossing pathologies of the corticospinal tract (CST) are rare and often associated with genetic disorders. However, they can be present in healthy humans and lead to ipsilateral motor deficits when a lesion to motor areas occurs. Here, we review historical and current literature of CST crossing pathologies and present a rare case of asymmetric crossing of the CST.

METHODS

Description of the case and systematic review of the literature were based on the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. The PubMed database was searched for peer-reviewed articles in English since 1950. All articles on ipsilateral stroke, uncrossed CST, and associated neurologic disorders were screened. Furthermore, a literature review between the years 1850 and 1980 including articles in other languages, books, opinions, and case studies was conducted.

RESULTS

Only a few descriptions of CST crossing pathologies exist in healthy humans, whereas they seem to be more common in genetic disorders such as horizontal gaze palsy with progressive scoliosis or congenital mirror movements. Our patient presented with aphasia and left-sided hemiparesis. Computed tomographic (CT) scan revealed a perfusion deficit in the left middle cerebral artery territory, which was confirmed by diffusion-weighted magnetic resonance imaging (MRI), so that thrombolysis was administered. Diffusion tensor imaging with fibre tracking revealed an asymmetric CST crossing.

CONCLUSIONS

The knowledge of CST crossing pathologies is essential if a motor deficit occurs ipsilateral to the lesion side. An ipsilateral deficit should not lead to exclusion or delay of therapeutic options in patients with suspected stroke. Here, a combined evaluation of CT perfusion imaging and MRI diffusion imaging may be of advantage.

Introducing and Reviewing a Novel Mutation of ROBO3 in Horizontal Gaze Palsy with Progressive Scoliosis from a Chinese Family

Horizontal gaze palsy with progressive scoliosis (HGPPS) is an autosomal recessive disorder caused by ROBO3 gene mutations. To date, the number of confirmed HGPPS cases caused by gene mutations is estimated at 76. However, HGPPS caused by ROBO3 gene mutation has not been reported in the Chinese population. In this study, the clinical data, brain imaging features, somatosensory evoked potentials (SEP), and ROBO3 gene mutations were obtained for two Chinese patients with HGPPS. The proband was an 11-year-old boy. He developed horizontal eye movement disorder at the age of 1 year and scoliosis at the age of 11 years. Two eyeballs fixed in the midline position were revealed by neurological examination. A dorsal cleft in the pons and a butterfly-shaped medulla were shown by brain magnetic resonance imaging. Again, most corticospinal bundles did not cross in the brainstem, as revealed by diffusion tensor imaging. SEP confirmed that most somatosensory projections were uncrossed. The proband's 7-year-old brother exhibited similar clinical manifestations and imaging features. The brothers had compound heterozygous mutations c.3165G>A (p.W1055X) and c.955G>A (p.E319K) of the ROBO3 gene. The c.3165G>A mutation is a novel nonsense mutation that has not been previously reported. This study reports the first two cases of HGPPS carrying a novel ROBO3 gene mutation in patients from a Chinese family, thereby expanding the disease spectrum. Reports from the literature show that missense mutation is the most common mutational type in the ROBO3 gene. Early ROBO3 gene detection is required for patients exhibiting early-onset eyeball movement disorder to confirm HGPPS disease.

Mutation in ROBO3 Gene in Patients with Horizontal Gaze Palsy with Progressive Scoliosis Syndrome: A Systematic Review

Horizontal gaze palsy with progressive scoliosis (HGPPS) is a rare, inherited disorder characterized by a congenital absence of conjugate horizontal eye movements with progressive scoliosis developing in childhood and adolescence. Mutations in the Roundabout (ROBO3) gene located on chromosome 11q23-25 are responsible for the development of horizontal gaze palsy and progressive scoliosis. However, some studies redefined the locus responsible for this pathology to a 9-cM region. This study carried out a systematic review in which 25 documents were analyzed, following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) standards. The search was made in the following electronic databases from January 1995 to October 2019: PubMed, Scopus, Web of Science, PEDRO, SPORT Discus, and CINAHL. HGPPS requires a multidisciplinary diagnostic approach, in which magnetic resonance imaging might be the first technique to suggest the diagnosis, which should be verified by an analysis of the ROBO3 gene. This is important to allow for adequate ocular follow up, apply supportive therapies to prevent the rapid progression of scoliosis, and lead to appropriate genetic counseling.

Clinical and Genetic Heterogeneity in Six Tunisian Families With Horizontal Gaze Palsy With Progressive Scoliosis: A Retrospective Study of 13 Cases

Background: Horizontal Gaze Palsy with Progressive Scoliosis (HGPPS) is a rare autosomal recessive congenital disorder characterized by the absence of conjugate horizontal eye movements, and progressive debilitating scoliosis during childhood and adolescence. HGPPS is associated with mutations of the ROBO3 gene. In this study, the objective is to identify pathogenic variants in a cohort of Tunisian patients with HGPPS and to further define ROBO3 genotype-phenotype correlations. Methods: Thirteen Tunisian patients from six unrelated consanguineous families all manifesting HGPPS were genetically investigated. We searched for the causative variants for HGPPS using classical Sanger and whole exome sequencing. Results: Four distinct homozygous mutations were identified in ROBO3 gene. Two of these were newly identified homozygous and non-synonymous mutations, causing effectively damage to the protein by in silico analysis. The other two mutations were previously reported in Tunisian patients with HGPPS. Mutations were validated by Sanger sequencing in parents and affected individuals. Conclusion: To the best of our knowledge, this is the largest ever reported cohort on families with HGPPS in whom ROBO3 mutations were identified. These molecular findings have expanded our knowledge of the ROBO3 mutational spectrum. The relevance of our current study is two-fold; first to assist proper management of the scoliosis and second to protect families at risk.

Horizontal Gaze Palsy with Progressive Scoliosis: A Case Report and Literature Review

Horizontal gaze palsy with progressive scoliosis (HGPPS) is a rare autosomal recessive disorder. The ROBO 3 gene mutation is responsible for the disease. We present a boy aged 12 years who was admitted for scoliosis surgery who had also had horizontal gaze palsy since birth. His brainstem abnormalities were compatible with the syndrome of HGPPS. HGPPS is one of the rare congenital diseases of childhood. Horizontal gaze palsy, ametropia, and progressive scoliosis are the main findings of the disease. This syndrome should be kept in mind for both ophthalmologists and orthopaedic surgeons in patients who present with gaze palsy and scoliosis. Early diagnosis of scoliosis makes it possible to treat the disease at an early stage, and early diagnosis of ametropia is important in the prevention of amblyopia.

Horizontal gaze palsy and progressive scoliosis with two novel ROBO3 gene mutations in two Jordanian families

BACKGROUND

Horizontal gaze palsy and progressive scoliosis (HGPPS) is a rare autosomal recessive disorder due to mutations in ROBO3 gene. Patients have characteristic clinical and imaging findings. We report six patients from two families with this disorder with two novel mutations.

MATERIALS AND METHODS

One patient from a non-consanguineous family and five patients from extended consanguineous families were clinically and radiologically examined. Blood samples from the patients and their parents were obtained and all the coding exons and flanking intronic sequences of the ROBO3 gene were amplified and subjected to bidirectional DNA sequencing.

RESULTS

All six patients had the characteristic clinical and radiological findings of HGPPS. Genetic testing showed two novel mutations including frame-shift and nonsense.

CONCLUSION

Two novel mutations in the ROBO3 gene were identified in two Jordanian families with six affected individuals. To our knowledge, this is the first molecular study of HGPPS in Jordan.

Ipsilateral Motor Innervation Discovered Incidentally on Intraoperative Monitoring: A Case Report

BACKGROUND AND IMPORTANCE: Lesions in the corticospinal tract above the decussation at the medullary pyramids almost universally produce contralateral deficits. Rare cases of supratentorial lesions causing ipsilateral motor deficits have been reported previously, but only ever found secondary to stroke or congenital pyramidal tract malformations.

CLINICAL PRESENTATION: Herein, we report a case of ipsilateral corticospinal tract innervation discovered incidentally with intraoperative monitoring during a microsurgical resection of a vestibular schwannoma. Intraoperative monitoring with electrical transcranial stimulation of the frontal scalp triggered motor-evoked potentials in the ipsilateral arms. The uncrossed pathways were later confirmed with MRI tractography using diffusion tensor imaging.

CONCLUSION: To the best of our knowledge, this is the first case of isolated ipsilateral motor innervation of the corticospinal tract discovered incidentally during a neurosurgical procedure. Given the increasing use of intraoperative monitoring, this case underscores the importance of cautious interpretation of seemingly discordant neurophysiological findings. Once technical issues have been ruled out, ipsilateral motor innervation may be considered as a possible explanation and neurosurgeons should be aware of the existence of this rare anatomic variant.

Congenital cranial dysinnervation disorders

The European Neuromuscular Centre (ENMC) derived the term Congenital Cranial Dysinnervation Disorders in 2002 at an international workshop for a group of congenital neuromuscular diseases. CCDDs are congenital, non-progressive ophthalmoplegia with restriction of globe movement in one or more fields of gaze. This group of sporadic and familial strabismus syndromes was initially referred to as the 'congenital fibrosis syndromes' because it was assumed that the primary pathologic process starts in the muscles of eye motility. Over the last few decades, evidence has accumulated to support that the primary pathologic process of these disorders is neuropathic rather than myopathic. This is believed that for normal development of extra ocular muscles and for preservation of muscle fiber anatomy, normal intra-uterine development of the innervation to these muscles is essential. Congenital dysinnervation to these EOMs can lead to abnormal muscle structure depending upon the stage and the extent of such innervational defects. Over last few years new genes responsible for CCDD have been identified, permitting a better understanding of associated phenotypes, which can further lead to better classification of these disorders. Introduction of high-resolution MRI has led to detailed study of cranial nerves courses and muscles supplied by them. Thus, due to better understanding of pathophysiology and genetics of CCDDs, various treatment modalities can be developed to ensure good ocular alignment and better quality of life for patients suffering from the same.

Horizontal gaze palsy and progressive scoliosis in a patient with congenital esotropia and inability to abduct. A case report

CASE REPORT

The case is presented on a 4- year-old child with congenital esotropia, limitation of abduction, cross-fixation, and thoracolumbar scoliosis. Genetic testing of ROBO3 gene confirmed the diagnosis of horizontal gaze palsy and scoliosis (HGPSS) DISCUSSION: HGPPS is a rare congenital disorder characterised by absence of conjugate horizontal eye movements and progressive scoliosis developed in childhood and adolescence. We highlight this motility disorder as a part of the differential diagnosis of early childhood esotropia with cross- fixation and limitation of abduction.

Axon guidance proteins in neurological disorders

Many neurological disorders are characterised by structural changes in neuronal connections, ranging from presymptomatic synaptic changes to the loss or rewiring of entire axon bundles. The molecular mechanisms that underlie this perturbed connectivity are poorly understood, but recent studies suggest a role for axon guidance proteins. Axon guidance proteins guide growing axons during development and control structural plasticity of synaptic connections in adults. Changes in expression or function of these proteins might induce pathological changes in neural circuits that predispose to, or cause, neurological diseases. For some neurological disorders, such as midline crossing disorders, investigators have identified causative mutations in genes for axon guidance. However, for most other disorders, evidence is correlative and further studies are needed to confirm the pathological role of defects in proteins for axon guidance. Importantly, further insight into how dysregulation of axon guidance proteins causes disease will help the development of therapeutic strategies for neurological disorders.

Ipsilateral hemiparesis caused by putaminal hemorrhage in a patient with horizontal gaze palsy with progressive scoliosis: a case report

BACKGROUND

Horizontal gaze palsy with progressive scoliosis (HGPPS) is an autosomal recessive disorder caused by mutations in the ROBO3 gene, resulting in a critical absence of crossing fibers in the brainstem.

CASE PRESENTATION

We present a patient with ipsilateral hemiparesis caused by putaminal hemorrhage who had a history of horizontal gaze paralysis and scoliosis since childhood. Diffusion tensor imaging (DTI) tractography confirmed the presence of uncrossed corticospinal tracts. Sequence analysis of the entire ROBO3 coding regions revealed a novel nonsense mutation.

CONCLUSION

We report the first known HGPPS case with intracranial hemorrhage and ROBO3 mutation showing an absence of major crossing pathways by DTI.

Infantile esotropia with cross-fixation, inability to abduct, and underlying horizontal gaze palsy with progressive scoliosis

Children affected by infantile esotropia can cross-fixate to see object to the contralateral side with the adducted eye; when doing so they need not abduct the eye ipsilateral to the object and thus can appear to have abduction defects. Less commonly, an esotropic child is truly unable to abduct and cross-fixates to allow side gaze. We report the case of a 10-month-old girl with cross-fixation and inability to abduct who was genetically proven to have horizontal gaze palsy with progressive scoliosis (recessive ROBO3 mutations). Clinical assessment of her elder brother, previously diagnosed with bilateral type 3 Duane retraction syndrome, revealed that he was actually affected by the same disease. We highlight this rare ocular motility disorder as part of the differential diagnosis of early childhood esotropia with cross-fixation and inability to abduct and how examination of an affected sibling can facilitate proper diagnosis of genetic eye disease.

Robo3.1A suppresses slit-mediated repulsion by triggering degradation of Robo2

Slits and Robos control the midline crossing of commissural axons, which are not sensitive to the midline repellent Slit before crossing but gain Slit responsiveness to exit the midline and avoid recrossing. Robo3.1A promotes midline crossing of commissural axons by suppressing the axonal responsiveness to the midline repellent Slit, but the underlying mechanism remains unclear. By using a cell surface binding assay and immunoprecipitation, we observed that Robo3.1A did not bind Slit on its own but prevented the specific binding of Slit to the cell surface when it was coexpressed with its close homologue Robo1 or Robo2 (Robo1/2), which are known to mediate the Slit repulsion. Cotransfection with Robo3.1A significantly reduced the protein level of Robo2 in HEK293 cells, and overexpression of Robo3.1A also significantly decreased Robo2 protein level in cerebellar granule cells. Downregulation of endogenous Robo3 by specific small interference RNA (siRNA) significantly increased Robo1 protein level, Slit binding to the cell surface was significantly elevated, and Slit-triggered growth cone collapse appeared after downregulation of Robo3 in cultured cortical neurons. Immunocytochemical staining showed that Robo2 and Robo3 colocalized in intracellular vesicles positive for the marker of late endosomes and lysosomes, but not trans-Golgi apparatus and early endosomes. Thus Robo3.1A may prevent the Slit responsiveness by recruiting Robo1/2 into a late endosome- and lysosome-dependent degradation pathway.

Horizontal gaze palsy with progressive scoliosis in a Moroccan family

Horizontal gaze palsy with progressive scoliosis (HGPPS) is a rare clinical condition characterized by a combination of horizontal gaze palsy, pendular nystagmus and scoliosis. Only a few cases have been previously described in the literature. Our observations serve to document the first cases in Morocco.

Roundabout receptors

Roundabout receptors (Robo) and their Slit ligands were discovered in the 1990s and found to be key players in axon guidance. Slit was initially described s an extracellular matrix protein that was expressed by midline glia in Drosophila. A few years later, it was shown that, in vertebrates and invertebrates, Slits acted as chemorepellents for axons crossing the midline. Robo proteins were originally discovered in Drosophila in a mutant screen for genes involved in the regulation of midline crossing. This ligand-receptor pair has since been implicated in a variety of other neuronal and non-neuronal processes ranging from cell migration to angiogenesis, tumourigenesis and even organogenesis of tissues such as kidneys, lungs and breasts.

Ipsilateral Stroke with Uncrossed Pyramidal Tracts and Underlying Right Internal Carotid Artery Stenosis Treated with Percutaneous Transluminal Angioplasty and Stenting

We present a unique case of ipsilateral stroke in a 55-year-old right-handed hypertensive man with proven uncrossed pyramidal tract demonstrated by tractography. Diffusion-weighted imaging disclosed small acute ischemic infarcts in the right corona radiata with MR angiography showing narrowing of the right internal carotid artery. Significant carotid stenosis of right internal carotid artery (ICA) was detected on digital subtraction angiography as the underlying cause and subsequently treated with percutananeous transluminal angioplasty and stenting with good outcome. The presence of uncrossed pyramidal tract was confirmed by diffusion tensor imaging tractography. To our knowledge there are few reports of ipsilateral stroke with proven uncrossed pyramidal tracts described in the literature. This is the first documented report of ipsilateral stroke with uncrossed fibre tracts due to underlying critical stenosis of the ICA treated successfully with a good recovery.

Human disorders of axon guidance

Axon pathfinding is essential for the establishment of proper neuronal connections during development. Advances in neuroimaging and genomic technologies, coupled with animal modeling, are leading to the identification of an increasing number of human disorders that result from aberrant axonal wiring. In this review, we summarize the recent clinical, genetic and molecular advances with regard to three human disorders of axon guidance: Horizontal gaze palsy with progressive scoliosis, Congenital mirror movements, and Congenital fibrosis of the extraocular muscles, Type III.

Imaging findings in congenital cranial dysinnervation disorders

In 2002, the term congenital cranial dysinnervation disorders (CCDDs) was proposed to group heterogeneous syndromes with congenital abnormalities of ocular muscle and facial innervations. The concept of neurogenic etiology has been supported by discovery of genes that are essential to the normal development of brainstem, cranial nerves, and their axonal connections. The CCDDs include Duane retraction syndrome, congenital fibrosis of the extraocular muscles, Möbius syndrome, horizontal gaze palsy with progressive scoliosis, the human homeobox-related disorders, pontine cap tegmental dysplasia, and an expanding list. The purpose of this review was to update the imaging features, as well as clinical and genetic information, regarding cases of CCDDs.

Horizontal gaze palsy and progressive scoliosis due to a deleterious mutation in ROBO3

PURPOSE

To describe a family with horizontal gaze palsy and progressive scoliosis with a deleterious mutation in the ROBO3 gene.

METHODS

All family members had full ophthalmologic, neurologic, and orthopedic examinations and complete sequencing of the ROBO3 gene.

RESULTS

Four affected members had complete loss of horizontal gaze with progressive scoliosis that varied between family members. ROBO3 sequencing revealed a novel 15 base deletion (c.2_16 delTGCTGCGCTACCTGC) in exon 1 that segregated in homozygous form with the phenotype and probably alters the shape and ionic charge of the extracellular immunoglobulin motif 1. This mutation was not detected in 100 control chromosomes.

CONCLUSIONS

The novel ROBO3 mutation in this family may be among the most deleterious yet reported. Family members in general were severely affected, but comparison of this family to other families with ROBO3 mutations did not yield a definitive phenotype-genotype correlation.

Horizontal gaze palsy and progressive scoliosis without ROBO3 mutations

BACKGROUND

To describe clinical and genetic observations in a patient with horizontal gaze palsy and progressive scoliosis (HGPPS) without identified mutations in the ROBO3 gene.

MATERIALS AND METHODS

Neurologic and orthopedic evaluation of the proband; sequencing all exons, exon-intron boundaries, and promoter region of ROBO3 in the proband and his mother. Array CGH was also carried out in the proband and his mother to evaluate possible chromosomal deletion(s) and/or duplication(s).

RESULTS

The proband had complete horizontal gaze restriction with full vertical gaze and small amplitude horizontal pendular nystagmus. He also had severe scoliosis and brainstem hypoplasia pathognomonic of HGPPS. However, complete sequencing of ROBO3 twice in both forward and reverse directions did not reveal any mutations. Array CGH investigation revealed no chromosomal abnormalities.

CONCLUSIONS

This patient had clinical and neuroimaging characteristics considered pathognomonic of HGPPS and yet did not have ROBO3 mutations. A clinical misdiagnosis is unlikely in the absence of facial weakness (typical of Moebius syndrome), deafness (typical of the HOXA1 spectrum), or mental retardation (typical of other central decussation abnormalities). It is perhaps more likely that a phenotype identical to HGPPS can be caused by abnormalities in ROBO3 splice variant expression, by mutations of a gene other than ROBO3, or by some environmental or epigenetic factor(s) inhibiting the action of ROBO3 or its protein product in the developing brainstem.

Ipsilateral Stroke in a Patient With Horizontal Gaze Palsy With Progressive Scoliosis and a Subcortical Infarct

Background and Purpose—

Horizontal gaze palsy with progressive scoliosis (HGPPS) is a rare congenital disorder caused by mutation in the ROBO3 gene. It is characterized by absent horizontal eye movements with progressive scoliosis developing in childhood and adolescence. To our knowledge, both diffusion tensor imaging evaluation in HGPPS patients who present with stroke and truncating stop codon mutation in the ROBO3 gene have yet to be reported.

Summary of Case—

We present a man with HGPPS who experienced a left pure motor stroke as a result of a left corona radiata infarct on diffusion-weighted imaging. Diffusion tensor imaging tractography confirmed the presence of uncrossed corticospinal tracts, accounting for the ipsilateral deficit. He was also found to possess a novel ROBO3 stop codon mutation on genetic testing.

Conclusions—

Patients with HGPPS may present with stroke symptoms on the ipsilateral side of the infarct in view of uncrossed corticospinal tracts. Truncating mutation in ROBO3 may provide additional pathophysiologic insights.