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The genetic landscape of crystallins in congenital cataract

Berry, Vanita; Ionides, Alex; Pontikos, Nikolas; Georgiou, Michalis; Yu, Jing; Ocaka, Louise A.; Moore, Anthony T.; Quinlan, Roy A.; Michaelides, Michel

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Vanita Berry

Alex Ionides

Nikolas Pontikos

Michalis Georgiou

Jing Yu

Louise A. Ocaka

Anthony T. Moore

Michel Michaelides


Background: The crystalline lens is mainly composed of a large family of soluble proteins called the crystallins, which are responsible for its development, growth, transparency and refractive index. Disease-causing sequence variants in the crystallins are responsible for nearly 50% of all non-syndromic inherited congenital cataracts, as well as causing cataract associated with other diseases, including myopathies. To date, more than 300 crystallin sequence variants causing cataract have been identified. Methods: Here we aimed to identify the genetic basis of disease in five multi-generation British families and five sporadic cases with autosomal dominant congenital cataract using whole exome sequencing, with identified variants validated using Sanger sequencing. Following bioinformatics analysis, rare or novel variants with a moderate to damaging pathogenicity score, were filtered out and tested for segregation within the families. Results: We have identified 10 different heterozygous crystallin variants. Five recurrent variants were found: family-A, with a missense variant (c.145C>T; p.R49C) in CRYAA associated with nuclear cataract; family-B, with a deletion in CRYBA1 (c.272delGAG; p.G91del) associated with nuclear cataract; and family-C, with a truncating variant in CRYGD (c.470G>A; W157*) causing a lamellar phenotype; individuals I and J had variants in CRYGC (c.13A>C; T5P) and in CRYGD (c.418C>T; R140*) causing unspecified congenital cataract and nuclear cataract, respectively. Five novel disease-causing variants were also identified: family D harboured a variant in CRYGC (c.179delG; R60Qfs*) responsible for a nuclear phenotype; family E, harboured a variant in CRYBB1 (c.656G>A; W219*) associated with lamellar cataract; individual F had a variant in CRYGD (c.392G>A; W131*) associated with nuclear cataract; and individuals G and H had variants in CRYAA (c.454delGCC; A152del) and in CRYBB1 (c.618C>A; Y206*) respectively, associated with unspecified congenital cataract. All novel variants were predicted to be pathogenic and to be moderately or highly damaging. Conclusions: We report five novel variants and five known variants. Some are rare variants that have been reported previously in small ethnic groups but here we extend this to the wider population and record a broader phenotypic spectrum for these variants.


Berry, V., Ionides, A., Pontikos, N., Georgiou, M., Yu, J., Ocaka, L. A., …Michaelides, M. (2020). The genetic landscape of crystallins in congenital cataract. Orphanet Journal of Rare Diseases, 15, Article 333.

Journal Article Type Article
Acceptance Date Nov 10, 2020
Online Publication Date Nov 26, 2020
Publication Date 2020
Deposit Date Nov 9, 2020
Publicly Available Date Nov 8, 2022
Journal Orphanet Journal of Rare Diseases
Publisher BioMed Central
Peer Reviewed Peer Reviewed
Volume 15
Article Number 333


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