Abstract
Purpose :
The aim of this cross-sectional study was to investigate whether the presence of BDNF Val66Met variant is associated with the structural (retinal nerve fibre layer (RNFL) thickness) and functional (amplitude and latency of multifocal visual evoked potentials (mfVEPs)) change in eyes of relapsing-remitting multiple sclerosis (RRMS) patients.
Methods :
48 RRMS patients were enrolled and underwent spectral domain optical coherence tomography (OCT) scans and mfVEP tests. Blood samples were collected, genomic DNA extracted and BDNF genotyping performed in all study participants. The visual functional and imaging parameters were compared between Met carriers (Val/Met and Met/Met genotype, n = 15) and Val homozygotes (n = 33). Both optic neuritis (ON) eyes and non-ON eyes were analysed and for patients without a history of ON, one eye was chosen at random.
Results :
The global (69.8 ± 13.9 vs 84.1 ± 12.6, p = 0.01) and temporal (37.4 ± 10.8 vs 55.1 ± 13.3, p = 0.002) RNFL thickness were significantly diminished in Met carriers compared to Val homozygotes in RRMS following ON attacks. Parallel to OCT variations, mfVEP also showed reduced amplitude (96.9 ± 58.5 vs 151.3 ± 50.9, p = 0.01) in ON eyes of Met carriers compared to the Val homozygotes. Non-ON eyes did not demonstrate any statistically significant differences between the two groups in either OCT or mfVEP parameters. Intra-subject asymmetry analysis (difference between ON and non-ON eyes) revealed pronounced global (24.2 ± 15.9 vs 6.6 ± 10.13, p = 0.002) and temporal (22.1 ± 12.9 vs 7.1 ± 15.0, p = 0.01) asymmetry in Met carriers compared to Val homozygotes. While amplitude asymmetry at baseline varied among the patients, it was, on average, significantly higher in Met carriers than in Val/Val group (51.7 ± 32.0 vs 16.1 ± 30.1, p = 0.009). There was also a significant difference between Met carriers and Val homozygotes (-22.0 ± 17.2 vs -7.7 ± 11.8, p = 0.02) in latency asymmetry.
Conclusions :
The carriage of Met allele was found to be associated with significant deficits within the retina after ON attacks in RRMS subjects but revealed no differences in non-ON eyes. BDNF Val66Met may affect the acute phase of ON in MS and may represent an increased vulnerability factor.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.