Mutation spectrum and genotype-phenotype correlations in Chinese congenital ectopia lentis patients

Abstract

Purpose: To identify the spectrum and frequency of mutations in congenital ectopia lentis (CEL) and to investigate the correlations between genotype and clinical phenotype in Chinese CEL patients.

Methods: Ninety-three participants with CEL were enrolled from March 2017 to April 2020. Ocular and systemic examinations were performed for each included patient. Genomic DNA from the included patients was analysed by whole-exome sequencing to detect mutations. Clinical manifestations were compared for different mutation subgroups.

Results: Gene mutations were detected in 79 patients. Sixty-five were FBN1-associated, and most were related to Marfan syndrome (MFS). The FBN1 mutations mainly consisted of missense mutations (49/65) and were concentrated in the 5' region. Probands with missense mutations tend to show high corneal astigmatism (χ² = 3.98, P = 0.046) and severe lens dislocation (t = 2.90, P = 0.006) compared to premature termination codon (PTC) mutations.

Conclusions: Most Chinese CEL patients were identified as having FBN1 mutations. Those with missense mutations commonly showed severe ocular phenotypes; therefore, reinforced follow-up and long-term observation are required. These correlations implicated the crucial role of missense and cysteine-involving mutations in ocular phenotypes, which might be explained by dominant-negative and nonsense-mediated mRNA decay (NMD).

Keywords: Ectopia lentis; FBN1; Genotype; Marfan syndrome; Mutation; Phenotype.