Dataset Information

Analysis of VSX1 Variations in Brazilian Subjects with Keratoconus.

ABSTRACT:

Purpose

To screen visual system homeobox 1 (VSX1) gene in Brazilian subjects affected with keratoconus (KCN).

Methods

Seventy-three patients with KCN and 106 healthy controls were enrolled in this study. Patients were diagnosed with KCN based on eye examination and corneal topographic features according to Rabinowitz's criteria (K > 47.2, I-S > 1.4 and KISA > 100%). DNA from blood samples was extracted from donors, and the exons and exon-intron boundaries of VSX1 were sequenced. The potential impact of the identified amino acid changes was assessed with Poly-Phen2, SIFT, and PMUT analysis tools. Genotyping was confirmed by RLFP technique, which was also applied to genotype non-affected individuals.

Results

We found three non-synonymous substitutions (L68H, R131S, and D105E) in VSX1 exon 1, with L68H mutation as a novel variation in this gene. In silico analysis indicated that all variations found were predicted to be probably damaging to VSX1 structure and function. Examination of R131S and L68H variations segregating in one family suggested a strong effect of these variations in increasing disease severity in the proband, which presented bilateral KCN leading to corneal grafting before the age of sixteen. We found a novel synonymous substitution (P79P) and two previously described exonic polymorphisms, with unknown roles in VSX1 pathogenesis.

Conclusion

VSX1 polymorphisms found in the Brazilian population support a genetic component in KCN pathogenesis. L68H is a novel mutation, and the phenotypic data suggest that this mutation might enhance disease severity when combined with other polymorphisms. However, further investigations are needed.

SUBMITTER: da Silva DC

PROVIDER: S-EPMC6058540 | biostudies-literature | 2018 Jul-Sep

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Analysis of VSX1 Variations in Brazilian Subjects with Keratoconus.

da Silva Dulceria Costa DC Gadelha Bianca Nery Benevides BNB Feitosa Alex Felipe Barbosa AFB da Silva Rafaela Gomes RG Albuquerque Tarsila Livia Paz E TLPE Santos Débora Christina Pereira Fernandes DCPF Gadelha Diego Nery Benevides DNB Fonseca Schamber-Reis Bruno Luiz BL

Journal of ophthalmic & vision research 20180701 3

<h4>Purpose</h4>To screen visual system homeobox 1 (<i>VSX1</i>) gene in Brazilian subjects affected with keratoconus (KCN).<h4>Methods</h4>Seventy-three patients with KCN and 106 healthy controls were enrolled in this study. Patients were diagnosed with KCN based on eye examination and corneal topographic features according to Rabinowitz's criteria (K > 47.2, I-S > 1.4 and KISA > 100%). DNA from blood samples was extracted from donors, and the exons and exon-intron boundaries of <i>VSX1</i> wer ...[more]

PMID: 30090183

Similar Datasets

Project description:BackgroundKeratoconus normally presents as a sporadic disease. Although different studies have found sequence variants of the visual system homeobox 1 (VSX1) gene associated with keratoconus in humans, no research has detected such variants in sporadic keratoconus patients from China. To investigate the possibility of VSX1 being a candidate susceptibility gene for Chinese patients with sporadic keratoconus, we performed sequence screening of this gene in such patients.MethodsWhole DNA was obtained from the leukocytes in the peripheral venous blood of 50 patients with sporadic keratoconus and 50 control subjects without this ocular disorder. Polymerase chain reaction single-strand conformation polymorphism analysis and direct DNA sequencing technology were used to detect sequence variation in the five exons and splicing regions of the introns of the VSX1 gene. The sequencing results were analyzed using DNAstar software.ResultsOne novel missense heterozygous sequence variant (p.Arg131Pro) was found in the first exon of the VSX1 gene in one keratoconus patient. Another heterozygous sequence variant (p.Gly160Val) in the second exon was found in two keratoconus patients. These variants were not detected in the control subjects. In the third intron of the VSX1 gene, c.8326G > A nucleotide substitution (including heterozygous and homozygous change) was also discovered. The frequency of this variation did not differ significantly between patients and controls, it should belong to single-nucleotide polymorphism of the VSX1 gene. Bioinformatic analysis also predicted that one missense sequence variation (p.Arg131Pro) may not cause a pathogenic change.ConclusionsIn this study, we added one novel missense sequence variation (p.Arg131Pro) in the coding region of the VSX1 gene to the range of VSX1 coding region variations observed in patients with sporadic keratoconus from China. Our work suggests that VSX1 sequence variants might be involved in the pathogenesis of sporadic keratoconus, but their precise role in disease causation requires further investigation.

Project description:BackgroundVisual system homeobox gene (VSX1) plays a major role in the early development of craniofacial and ocular tissues including cone opsin gene in the human retina. To date, few disease-causing mutations of VSX1 have been linked to familial and sporadic keratoconus (KC) in humans. In this study, we describe the clinical features and screening for VSX1 gene in families with KC from India.MethodsClinical data and genomic DNA were collected from patients with clinically diagnosed KC and their family members. The study was conducted on 20 subjects of eight families from India. The coding exons of VSX1 gene were amplified using PCR and amplicons were analyzed by direct sequencing. Predictive effect of the mutations was performed using Polyphen-2, SIFT and mutation assessor algorithms. Additionally, haplotypes of VSX1 gene were constructed for affected and unaffected individuals using SNPs.ResultsIn the coding region of VSX1, one novel missense heterozygous change (p.Leu268His) was identified in five KC patients from two unrelated families. Another family of three members had a novel heterozygous change (p.Ser251Thr). These variants co-segregated with the disease phenotype in all affected individuals but not in the unaffected family members and 105 normal controls. In silico analysis suggested that p.Leu268His could have a deleterious effect on the protein coded by VSX1, while p.Ser251Thr has a neutral effect on the functional properties of VSX1. Haplotype examination revealed common SNPs around the missense change (p.Leu268His) in two unrelated KC families.ConclusionsIn this study, we add p.Leu268His, a novel missense variation in the coding region of VSX1 to the existing repertoire of VSX1 coding variations observed in Indian patients with the characteristic phenotype of KC. The variant p.Ser251Thr might be a benign polymorphism, but further biophysical studies are necessary to evaluate its molecular mechanism. The shared haplotype by two families with the same variant suggests the possibility of a founder effect, which requires further elucidation. We suggest that p.Leu268His might be involved in the pathogenesis of KC, which may help in the genetic counselling of patients and their family.

Dataset Information

Analysis of VSX1 Variations in Brazilian Subjects with Keratoconus.

Purpose

Methods

Results

Conclusion

Publications

Analysis of VSX1 Variations in Brazilian Subjects with Keratoconus.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets