Mitochondrial Dna Variations In Keratoconus: Understanding Morphological Changes, Oxidative Stress, And Prognostic Implications
Published 2024 - 42nd Congress of the ESCRS
Reference: PP01.02 | Type: Free paper | DOI: 10.82333/2kb3-c373
Authors: Shivam Sharma* 1 , Lata Singh 2 , Tapas Chandra Nag 3 , Seema Kashyap 4 , Seema Sen 4 , Namrata SHARMA 1
1Dr. R. P. Centre for Ophthalmic Sciences,All India Institute of Medical Science,New Delhi,India, 2Paediatrics,All India Institute of Medical Science,New Delhi,India, 3Anatomy,All India Institute of Medical Science,New Delhi,India, 4Ocular Pathology,All India Institute of Medical Science,New Delhi,India
Purpose
Keratoconus (KC) is thinning of corneal stroma & irregular astigmatism, resulting in diminution of vision. Despite its prevalence, the underlying etiology is poorly understood. Emerging evidence suggests a dysregulation of oxidative balance and mitochondrial function in KC corneas. Therefore, our study conducted the whole mitochondrial DNA (mtDNA) genome sequencing to study the mtDNA variations along with the analysis of ultrastructural morphology and oxidative stress in KC patients.
Setting
It is a prospective, cross-sectional pilot study at Dr. R. P. Centre for Ophthalmic Science & department of anatomy AIIMS New Delhi.
Methods
Twenty KC patients were recruited in this prospective study. Blood and cornea from same patients were collected for performing mtDNA genome sequencing. Whole mtDNA sequencing was done by preparing libraries followed by next generation sequencing using illumina HISeqX sequencer. 1mm x 1mm corneal tissue was also processed for transmission electron microscopy (TEM). mRNA expression levels of oxidative stress genes were measured by quantitative real-time PCR (qRT-PCR) in corneal tissues.
Results
In our study, variations were found in both D-loop region (non-coding) and coding region. Most common variations were T to C and C to T followed by A to G in D-loop & coding region. Total of 389 variations at different position were found in coding region. There were 237 variations reported as pathogenic in HmtVar database. TEM showed disorganized and degraded mitochondria with dissolved cristae content. qRT-PCR results showed the upregulation of SOD1, GPX4 & NOX2 genes in our cases. These variations were statistically significant with the disease severity and diminution of vision (p<0.001).
Conclusions
This is the first study showing high frequency of mtDNA mutation in Indian population of KC corneas which might be due to abnormal morphology of mitochondria. Our findings highlight the potential utility of mtDNA variations and structural alterations as prognostic marker for KC patients. Mitochondrial dysfunction may be considered as a genetic risk factor contributing indirectly through the oxidative stress mechanism to the development and/or progression of KC.