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

Horizontal gaze palsy with progressive scoliosis: Further expanding the ROBO3 spectrum

OBJECTIVE

Horizontal gaze palsy with progressive scoliosis (HGPPS) is a rare, autosomal recessive disorder resulting from axonal midline crossing defect due to variants in ROBO3.

METHODS

We retrospectively evaluated demographics, clinical phenotype, course of spinal deformities, and neuroimaging findings of six Turkish patients with HGPPS. We performed targeted gene testing by next-generation sequencing.

RESULTS

The median age at symptom onset and diagnosis was 1.5 years (0.5-4), and 11 years (2-16), respectively. Oculomotor signs were the most common presenting symptom (n = 4), followed by scoliosis (n = 2). The course of scoliosis was progressive and accompanied by kyphosis, showed intrafamilial variability, and was corrected surgically in three of the patients. Intellectual disability (n = 4), hypergonadotropic hypogonadism (n = 2), hearing loss (n = 2), and tranisent movement disorders (n = 1) were additional features. Targeted gene sequencing revealed five distinct homozygous variants. Of the four novel variants, two of them were located in the acceptor site of the noncoding region of the gene, remaining two were missense and frameshift variants, located in immunoglobulin-like domain-2, and cytoplasmic signaling motif 2, respectively. Structural magnetic resonance imaging (MRI) and diffusion tensor imaging (DTI) showed the absence of decussation of superior cerebellar peduncle and dorsal transverse pontine fibers.

INTERPRETATION

Spectrum of HGPPS is further expanded with novel variants in the ROBO3 with clinical and radiological fingerprints. Spinal deformities require close orthopedic screening and individualized approach. Intellectual disability and hearing loss emerge as additional features. Hypogonadism and transient subtle movement disorders require further attention and confirmation from other series.

Study on the relationship between scoliosis and vision problems: A narrative review

Adolescent scoliosis is one of the most common surgical disorders of the pediatric spine. With timely detection and early treatment, most scoliotic children can avoid major and expensive surgery. Vision problems are also frequently found at an early age and can take a toll on individuals quality of life. However, scoliosis, a severe health hazard to adolescents, is often accompanied by vision problems clinically, including myopia, astigmatism, strabismus, amblyopia, horizontal paralysis, and blindness. And people with genetic defects have a higher probability of suffering both spinal problems and vision problems than those with nongenetic defects. However, many individuals viewed scoliosis and vision problems as 2 irrelevant diseases. This review searched PubMed, China National Knowledge Infrastructure, and Web of Science for studies on adolescent, scoliosis, eye diseases, myopia, strabismus, spinal disorders, and vision problems for almost 3 decades, and thus confirmed the potential relationship between adolescent scoliosis and vision problems.

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.

Clinical features and genotypes of six patients from four families with horizontal gaze palsy with progressive scoliosis

BACKGROUND

Horizontal gaze palsy with progressive scoliosis (HGPPS) is a rare disorder mainly involved in ocular movement and spinal development. It is caused by a roundabout guidance receptor 3 (ROBO3) gene mutation. This study aimed to describe the clinical features of six patients with HGPPS and investigate the corresponding ROBO3 gene mutations.

METHODS

Patients underwent detailed clinical and imaging examinations. Whole-exome sequencing was performed to detect nucleotide variations in the disease-causing genes of HGPPS.

RESULTS

Six pathogenic variants were detected in the ROBO3 gene from six patients with HGPPS, including two novel compound heterozygous mutations, c.1447C > T (p.R483X) and c.2462G > C (p.R821P); c.1033G > C (p.V345L) and c.3287G > T (p.C1096F); a novel homozygous indel mutation, c.565dupC (p.R191Pfs*61); and a known missense mutation, c.416G > T (p.G139V). Patients with HGPPS had horizontal conjugated eye movement defects and scoliosis with variable degrees, as well as flattened pontine tegmentum and uncrossed corticospinal tracts on magnetic resonance imaging.

CONCLUSION

Our genetic findings will expand the spectrum of ROBO3 mutations and help inform future research on the molecular mechanism of HGPPS.