Novel gene variants in Polish patients with Leber congenital amaurosis (LCA)

Abstract

Background Leber congenital amaurosis (LCA) is a rare retinal disease that is the most frequent cause of congenital blindness in children and the most severe form of inherited retinal dystrophies. To date, 25 genes have been implicated in the pathogenesis of LCA. As gene therapy is becoming available, the identification of potential treatment candidates is crucial. The aim of the study was to report the molecular basis of Leber congenital amaurosis in 22 Polish families. Methods Single Nucleotide Polymorphism-microarray for LCA genes or Next Generation Sequencing diagnostic panel for LCA genes (or both tests) were performed to identify potentially pathogenic variants. Bidirectional Sanger sequencing was carried out for validation and segregation analysis of the variants identified within the families. Results The molecular background was established in 22 families. From a total of 24 identified variants, 23 were predicted to affect protein-coding or splicing, including 10 novel variants. The variants were identified in 7 genes: CEP290, GUCY2D, RPE65, NMNAT1, CRB1, RPGRIP1, and CRX. More than one-third of the patients, with clinical LCA diagnosis confirmed by the results of molecular analysis, appeared to be affected with a severe form of the disease: LCA10 caused by the CEP290 gene variants. Intronic mutation c.2991+1655A>G in the CEP290 gene was the most frequent variant identified in the studied group. Conclusions This study provides the first molecular genetic characteristics of patients with Leber congenital amaurosis from the previously unexplored Polish population. Our study expands the mutational spectrum as we report 10 novel variants identified in LCA genes. The fact that the most frequent causes of the disease in the studied group of Polish patients are mutations in one out of three genes that are currently the targets for gene therapy (CEP290, GUCY2D, and RPE65) strongly emphasizes the importance of the molecular background analyses of LCA in Polish patients.

Retinal Degeneration Associated With RPGRIP1: A Review of Natural History, Mutation Spectrum, and Genotype–Phenotype Correlation in 228 Patients

“…Hanein et al (2004) suggested a clinical flowchart according to which a child manifesting nystagmus, profound visual deficiency, and unrecordable ERG at birth or during the first months of life and developing photophobia, showing hypermetropia with a refractive error lower than +7, and VA better than FC, but worse than 1/20, will probably have RPGRIP1 or AIPL1 mutations. While this flowchart holds true for many of the 228 RPGRIP1 patients included in the present analysis (from multiple centers and publications), not all patients with RPGRIP1 causative mutations have nystagmus from birth (156 patients, which are 68%), a minority still have recordable ERG responses even after the age of 10 years, approximately 25% of patients are nyctalopic, 20% (25/124, 7 of them had NLP) of patients had VA lower than FC (Dryja et al, 2001;Galvin et al, 2005;McKibbin et al, 2010;Walia et al, 2010;Chen et al, 2013;Fakhratova, 2013;Huang et al, 2013Huang et al, , 2017Khan et al, 2013Khan et al, , 2014Wang et al, 2016;Han et al, 2017;Jinda et al, 2017;Hosono et al, 2018;Weisschuh et al, 2018;Avela et al, 2019;Jamshidi et al, 2019;Sallum et al, 2020;Skorczyk-Werner et al, 2020), and 25% (32/124) had a VA better than 1/20 (McKibbin et al, 2010;Fakhratova, 2013;Suzuki et al, 2014;Saqib et al, 2015;Han et al, 2017;Huang et al, 2017;Birtel et al, 2018;Weisschuh et al, 2018;Imani et al, 2018;Miyamichi et al, 2019;Skorczyk-Werner et al, 2020;Sallum et al, 2020;Sato et al, 2020). In addition, there are p...…”

“…For example, nystagmus and oculodigital signs do not appear in all patients. While most of the patients are hyperopic (Dryja et al, 2001;Galvin et al, 2005;Fakhratova, 2013;Khan et al, 2013Khan et al, , 2014Verma et al, 2013;Suzuki et al, 2014;Wang et al, 2016;Han et al, 2017;Huang et al, 2017;Sato et al, 2020), some myopic patients were identified (Tiwari et al, 2016;Imani et al, 2018); most of the patients reported light aversion (McKibbin et al, 2010;Fakhratova, 2013;Huang et al, 2013;Khan et al, 2013Khan et al, , 2014Suzuki et al, 2014;Saqib et al, 2015;Wang et al, 2016;Sato et al, 2020;Skorczyk-Werner et al, 2020), but some emphasize nyctalopia as a major visual symptom (McKibbin et al, 2010;Birtel et al, 2018;Miyamichi et al, 2019). Hanein et al (2004) suggested a clinical flowchart according to which a child manifesting nystagmus, profound visual deficiency, and unrecordable ERG at birth or during the first months of life and developing photophobia, showing hypermetropia with a refractive error lower than +7, and VA better than FC, but worse than 1/20, will probably have RPGRIP1 or AIPL1 mutations.…”

Clinical and genetic findings in TRPM1‐related congenital stationary night blindness

“…A significant proportion of these changes are variants that impact on splicing despite being distal to the intron-exon junction (like the TRPM1 c.965 + 29G>A change found in a participant of this study). Such sequence alterations have been reported in a number of genes associated with retinal diseases including ABCA4, USH2A, CACNA1F, CEP290, GUCY2D and RPE65 (den Hollander et al 2006;Liquori et al 2016;Sangermano et al 2019;Zeitz et al 2019;Skorczyk-Werner et al 2020). Identifying such changes is particularly important as there are implications for therapeutic development, given that this group of variants has been shown to be Fig.…”

“…2019; Skorczyk‐Werner et al. 2020). Identifying such changes is particularly important as there are implications for therapeutic development, given that this group of variants has been shown to be amenable to anti‐sense oligonucleotide and CRISPR‐Cas9 approaches (Garanto et al.…”

Voretigene Neparvovec for the Treatment of RPE65-associated Retinal Dystrophy: Consensus and Recommendations from the Korea RPE65-IRD Consensus Paper Committee

“…The proportions of RPE65associated LCA varied considerably in various countries, from 1.26% up to 95% in clinically diagnosed patients [2, and from 3.95% to 40% among those with a molecular diagnosis of IRD [2,25,27,37,[42][43][44][45][46]. The proportion of RPE65 gene mutations in LCA families worldwide was estimated at 6.15% [47], but the percentages of the mutation-carrying families from various countries differed substantially, from 1% to 18.18% in clinically diagnosed cases [48][49][50][51][52] and from 7.14% to 13.64% in molecularly diagnosed ones [2,53,54] (Table 1). The prevalence of RP worldwide was reported at 11.09 to 47.62 per 100,000 [5,[55][56][57][58][59][60][61][62][63][64][65][66][67][68].…”