Benedict Rak

Dr. Benedict Rak


Research Focus & Metrics

Academic Career Length

5Years (2022-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

View All Publications
10 October 2022 in Diagnostics
Verified
Journal Article
Open access
PDF file
AĆAna Ćurić
Ana Ćurić
MBMirjana Bjeloš
Mirjana Bjeloš
MBMladen Bušić
Mladen Bušić
BEBiljana Kuzmanović Elabjer
Biljana Kuzmanović Elabjer
BRBenedict Rak
Benedict Rak
NVNenad Vukojević
Nenad Vukojević
The purpose of the study was to investigate the long-term effects of uncomplicated phacoemulsification on macular perfusion using optical coherence tomography angiography (OCTA) in healthy aging subjects. OCTA was performed before phacoemulsification and 1 week, 1 month, 3 months, and 6 months after. Superficial vascular complex (formed of nerve fiber layer vascular plexus and superficial vascular plexus), deep vascular complex (formed of intermediate capillary plexus and deep capillary plexus), as well as choriocapillaris (CC) and large choroidal blood vessels were recorded. Significant changes of vascular parameters in 95 eyes of 95 patients reached plateau 1 week after surgery and remained stable up to 6 months, occurring in all retinal layers but not in choroid and CC. Statistically significant increases in retinal vessels area, vessels percentage area, total number of junctions, junctions density, and total and average vessels length were found, followed by the total number of end points and mean lacunarity decline, proving an increase in blood supply. The study confirmed that uncomplicated phacoemulsification leads to a long-term increase in macular retinal perfusion. The results might ease the decision regarding timing for cataract surgery as long-term perfusion benefits can be achieved. Furthermore, study results provide a normative database of retinal and choroidal vasculature in healthy aging patients.

Verified
Journal Article
Open access
PDF file
MBMirjana Bjeloš
Mirjana Bjeloš
AĆAna Ćurić
Ana Ćurić
BRBenedict Rak
Benedict Rak
BEBiljana Kuzmanović Elabjer
Biljana Kuzmanović Elabjer
MBMladen Bušić
Mladen Bušić
KRKatja Rončević
Katja Rončević
Disease-causing variants in the IDH3A gene are associated with autosomal recessive retinitis pigmentosa 90 (RP90) and Leber congenital amaurosis, with or without macular pseudocoloboma. Here, we report two patients: one compound heterozygous for IDH3A c.364G>A, p.(Ala122Thr), which has conflicting classifications, and for IDH3A c.293C>T, p.(Pro98Leu), which is likely pathogenic, and the other homozygous for IDH3A c.364G>A, p.(Ala122Thr). This study is aimed at providing evidence to link the latter variants to a clinical phenotype. The first patient was a 6-year-old girl, and the second patient was a 29-year-old female. In both patients, the diagnostic assessments were consistent with the phenotype of RP, characterized by macular pseudocoloboma but of varying severity. Patients’ phenotypes suggest that the c.293C>T, p.(Pro98Leu) variant is linked to a more severe and extensive clinical phenotype, while the c.364G>A, p.(Ala122Thr) variant results in a milder condition, primarily limited to retinal involvement. In Patient 2, the presence of both global and local stereopsis, indicating advanced visual development, suggests that the p.(Ala122Thr) missense variant may act as a hypomorphic allele which likely allows for some residual enzymatic activity of the IDH3A protein. This report highlights that macular pseudocoloboma can manifest even in the absence of a null variant. In contrast, more severe symptoms, such as mitochondrial encephalopathy, seem to be associated with the presence of a null allele. Furthermore, to the best of our knowledge, this is the first report of the IDH3A c.293C>T, p.(Pro98Leu) variant.

Verified
Journal Article
Open access
PDF file
MBMirjana Bjeloš
Mirjana Bjeloš
MBMladen Bušić
Mladen Bušić
AĆAna Ćurić
Ana Ćurić
BŠBorna Šarić
Borna Šarić
DBDamir Bosnar
Damir Bosnar
BRBenedict Rak
Benedict Rak
Precise genetic diagnosis in RPE65-mediated retinitis pigmentosa (RP) is necessary to establish eligibility for genetic treatment with voretigene neparvovec: a recombinant adeno-associated viral vector providing a functional RPE65 gene. This case report aims to report a novel RP-related point mutation RPE65 c.353G>A, p.(Arg118Lys), a variant of uncertain significance associated with a severe clinical presentation and the striking phenotypic feature of complete macular atrophy. We report the case of a 40-year-old male with inherited retinal dystrophy, all features typical for the RPE65-associated RP, and marked macular atrophy. Genetic testing identified that the patient was a compound heterozygote in trans form with two heterozygous variants: RPE65 c.499G>T, p.(Asp167Tyr) and RPE65 c.353G>A, p.(Arg118Lys). Furthermore, short-wavelength and near-infrared autofluorescence patterns exhibited deficiencies specific to mutations in the visual cycle genes. To the best of our knowledge, RPE65 c.353G>A, p.(Arg118Lys) is the first described point mutation on this locus, among all other reported insertional mutations, currently classified as likely benign and of uncertain significance. We concluded that this variant contributed to the pathological phenotype, demonstrating its significance clearly to be reclassified as likely pathogenic. This being the case, patients with this specific variant in homozygous or compound heterozygous form would be likely candidates for genetic treatment with voretigene neparvovec.

23 July 2024 in Diagnostics
Verified
Journal Article
Open access
PDF file
MBMirjana Bjeloš
Mirjana Bjeloš
AĆAna Ćurić
Ana Ćurić
MBMladen Bušić
Mladen Bušić
BRBenedict Rak
Benedict Rak
BEBiljana Kuzmanović Elabjer
Biljana Kuzmanović Elabjer
We present two children aged 3 and 5 years who share identical TYR genotype, yet exhibit contrasting phenotypic manifestations in terms of eye, skin, and hair coloration. The patients are heterozygous for TYR c.1A>G, p. (Met1?), which is pathogenic, and homozygous for TYR c.1205G>A, p. (Arg402Gln), which is classified as a risk factor. The children manifested diminished visual acuity, nystagmus, and foveal hypoplasia. The first patient presented with hypopigmentation of the skin, hair, and ocular tissues, while the second patient presented with hypopigmentation of the skin, hair, retinal pigment epithelium, and choroid with dark brown irises. Furthermore, the brown-eyed subject presented astigmatic refractive error and both global and local stereopsis capabilities, contrasting with the presentation of hypermetropia, strabismus, and the absence of stereopsis in the blue-eyed individual. Herein, we propose a genotype–phenotype correlation model to elucidate the diverse clinical presentations stemming from biallelic and triallelic pathogenic variants in TYR, establishing a link between the residual tyrosinase activity and resultant phenotypes. According to our proposed model, the severity of TYR variants correlates with distinct albino phenotypes. Our findings propose the potential association between reduced pigmentation levels in ocular tissues and binocular functions, suggesting pigmentation as a possible independent variable influencing the onset of strabismus—an association unreported until now in the existing literature.

29 July 2022 in Ophthalmic Genetics
Verified
Journal Article
Closed access
MBMirjana Bjeloš
Mirjana Bjeloš
MBMladen Bušić
Mladen Bušić
AĆAna Ćurić
Ana Ćurić
DBDamir Bosnar
Damir Bosnar
BŠBorna Šarić
Borna Šarić
BRBenedict Rak
Benedict Rak
It is of utmost importance to define the molecular diagnosis of patients with retinitis pigmentosa (RP) due to existing targeted therapeutic option: voretigene neparvovec.We provide clinical eviden...

Verified
Journal Article
Open access
PDF file
MBMirjana Bjeloš
Mirjana Bjeloš
AĆAna Ćurić
Ana Ćurić
MBMladen Bušić
Mladen Bušić
BRBenedict Rak
Benedict Rak
BEBiljana Kuzmanović Elabjer
Biljana Kuzmanović Elabjer
We present a case involving a patient whose clinical phenotype aligns with oculocutaneous albinism (OCA), yet exhibits a complex genotype primarily characterized by variants of unknown significance (VUS). An 11-year-old boy manifested iris hypopigmentation and translucency, pronounced photophobia, diminished visual acuity and stereopsis, nystagmus, reduced pigmentation of the retina, and foveal hypoplasia. Genetic testing was performed. A heterozygous missense VUS CAPN5 c.230A>G, p.(Gln77Arg), a heterozygous missense VUS TYR c.1307G>C, p.(Gly436Ala), and a heterozygous missense variant TYR c.1205G>A, p.(Arg402Gln) which was classified as a risk factor, were identified. We hypothesized that the TYR c.1307G>C, p.(Gly436Ala) variant is in genetic disequilibrium with the TYR c.1205G>A, p.(Arg402Gln) variant leading to deficient expression of melanogenic enzymes in retinal cells, resulting in the manifestation of mild OCA. Additionally, this study represents the case where we did not detect chiasmal misrouting in visual evoked potentials, nor did we observe a shift in the distribution of ganglion cell thickness from a temporal to a central position. Moreover, our patient’s case supports the probable benign nature of the CAPN5 c.230A>G, p.(Gln77Arg) variant.