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Objective To observe and analyze the ocular clinical features and pathogenic genes of horizontal gaze palsy with progressive scoliosis (HGPPS).
Methods A pedigree study was conducted.Two families with HGPPS diagnosed by ophthalmology examination at Henan Children’s Hospital from November 2023 to April 2024 were included, with 3 people from two generations in each family.Medical history and family history of the subjects were inquired.Vision acuity, diopter, anterior segment, intraocular pressure, wide-angle laser scanning ophthalmoscopy, optical coherence tomography, visual evoked potential (VEP), electroretinogram (ERG), ocular B-ultrasound, full spine AP+ lateral view, orbit+ skull+ cervical spine+ thoracic spine+ lumbosacral spine MRI plain scan were performed on the subjects.Whole genomic DNA was extracted from 2 ml of peripheral venous blood collected from the subjects, and gene sequencing was performed using whole exome sequencing (WES) technology.Suspicious pathogenic variant loci were verified by Sanger sequencing, and the pathogenicity of gene variant loci was analyzed according to the ACMG standards and guidelines for the interpretation of sequence variants.This study followed the Declaration of Helsinki.The study protocol was reviewed and approved by the Ethics Committee of Henan Children’s Hospital (No.2024-KY-0024).All subjects and guardians signed informed consent forms and were informed of relevant matters before genetic testing.
Results The proband from family 1 was male, 3 years and 2 months old.At the age of 6 months, he was found to have head tilted to the left with a right scoliosis of the spine centered on T11-12 and no obvious abnormalities on VEP and ERG examinations.The proband from family 2 was male, 3 years and 4 months old, with a left scoliosis of the spine centered on T12.Both probands developed horizontal fixation paralysis, unable to rotate eye outward, slightly limited inward rotation, left eye hypertropia, mild horizontal nystagmus, normal vertical eye movement, backward development of major movements, and normal vision, anterior segment and fundus.MRI examination showed that the medulla oblongata was butterfly shaped, and a brainstem fissure could be seen in the center of the medulla oblongata.The genetic testing showed that the proband from family 1 had compound heterozygous variations c. 1054delC/p.Gln352Serfs *90 (M1) in exon 7 and c. 1219G>T/p.Gly407Cys (M2) in exon 8 of ROBO3 gene.The father of the proband carried M1 and the mother of the proband carried M2.The proband from family 2 had compound heterozygous variations c. 1888C>T/p.R630X (M3) in exon 12 and c. 2684C>A/p.A895E (M4) in exon 17 of ROBO3 gene.M1 and M3 were possible pathogenic, and M2 and M4 were of unknown clinical significance, and prediction software predicted M2 and M4 were harmful variations.
Conclusions The main clinical features of two HGPPS pedigree are horizontal fixation paralysis and progressive scoliosis, accompanied by nystagmus and strabismus.MRI shows brainstem fissure in the central medullary area.Four variants are novel variants, which increases the variation spectrum of ROBO3 gene.