Pathogenic variants in ADAMTSL4 are an important cause of isolated ectopia lentis with an increasing number of genetically confirmed cases internationally. We sought to better describe ocular features seen with pathogenic variants in ADAMTSL4. We performed a retrospective, multicenter study examining the phenotypic and genotypic spectrum of ADAMTSL4-associated ocular disease. We identified 41 individuals from 32 families with genetically confirmed ADAMTSL4-related disease across six tertiary referral centers across Europe. Identified participants had a young age of diagnosis (median 1.3 years) and a highly myopic refractive error (mean SE -10.27 D). A diagnosis of ectopia lentis et pupillae was made in a third of cases, with a younger age at diagnosis (median 0.5 years). Subluxation tended to be in the inferior direction (~33%). Zonules were noted to be missing or absent in the majority of cases. Sixteen different pathogenic variants in ADAMTSL4 were reported. A previously reported 20-bp deletion (c.767_786del) was highly prevalent in this cohort (23/32), and all ectopia lentis et pupillae cases carried this variant. ADAMTSL4-related disease tends to present at a younger age and be associated with higher myopia than other forms of ectopia lentis (such as FBN1). Early identification of typical phenotypic features alongside genetic testing can aid early, precise diagnosis and prevent unnecessary investigations.

This study aimed to identify the potential genetic defects underlying familial clustering of lens dislocation in two unrelated Turkish families, consistent with the clinical features of isolated ectopia lentis (IEL). The investigation seeks to determine whether the detected findings overlap with those observed in other syndromic conditions that present with lens dislocation. Additionally, a focused review of IEL within the scientific literature was conducted to contextualize the molecular and phenotypic spectrum associated with lens abnormalities. The results of this study are expected to contribute to a deeper understanding of the molecular basis of IEL and to enhance diagnostic precision, genetic counseling, and clinical management strategies for affected individuals. Comprehensive family histories and clinical evaluations revealed lens dislocation and associated ocular manifestations without systemic abnormalities or extraocular features suggestive of connective tissue disorders. Whole-exome sequencing (WES) in affected individuals identified two heterozygous FBN1 missense variants. The first variant, ENST00000316623.5:c.2920C>T, which has been previously reported in the literature, is located within the TB5 domain and was identified in ten affected members of family 1. The second variant, ENST00000316623.5:c.7018T>C, located within the TB9 domain, was identified in a single affected individual from family 2 and is reported here for the first time in association with IEL. Segregation analysis demonstrated that both variants co-segregated with the ectopia lentis phenotype and were completely absent in unaffected family members as well as in WES data from 200 ophthalmologically normal in-house controls. Besides, our study focused review of the literature on FBN1-associated IEL revealed that approximately 66.7% of reported variants involve missense substitutions affecting cysteine residues. Our study further reinforces this pattern by identifying two rare FBN1 missense variants that co-segregate with the phenotype, thereby expanding the known mutational spectrum of IEL. These findings also underscore the phenotypic heterogeneity of IEL, as reflected by the variable age of onset among affected individuals, and emphasize the critical role of domain-specific cysteine-altering mutations in the pathogenesis of IEL.

Mutations in fibrillin-1 (FBN1) cause various clinical conditions, such as Marfan syndrome (MFS). However, the genotype-phenotype relationships underlying MFS and other conditions relevant to FBN1 mutations have not been fully elucidated. We performed whole-exome sequencing on three participants, including an affected mother-daughter pair, in a three-generation Japanese family with isolated ectopia lentis (IEL). The sequencing identified a novel single-nucleotide variant (c.1327+3A>C) in intron 11 of FBN1 that was shared between the two patients. We confirmed the co-segregation of the variant with IEL in two additional affected relatives in the family. The Combined Annotation-Dependent Depletion score of the variant was 26.1, which was indicated by SpliceAI to influence splicing, with a score of 0.93. Reverse transcription-polymerase chain reaction (RT-PCR) of mRNAs isolated from peripheral blood mononuclear cells revealed aberrant bands in all four affected individuals. Subsequent sequencing revealed that these bands originated from FBN1 transcripts lacking exon 11. The causality of the variant in the skipping of exon 11, which results in an in-frame deletion of 60 amino acids corresponding to the "hinge" region of FBN1 protein, was confirmed in a minigene experiment. Interestingly, the same result was observed for a minigene for c.1327+1G>A, a variant previously identified in two unrelated EL families without MFS manifestations. These results suggest that the c.1327+3A>C mutation in FBN1 likely leads to IEL. The findings expand our knowledge of FBN1 and provide insights into FBN1-related diseases.

Purpose: To present a series of 4 patients from the Ohio Amish or Mennonite populations with isolated ectopia lentis. Methods: A case series was evaluated. Results: Four cases with bilateral lens subluxations were diagnosed with a homozygous c.767_786del pathogenic variant in ADAMTSL4. Their ages ranged from 2 to 22 years. Three cases were symptomatic and were managed surgically with lensectomy, vitrectomy, and endolaser photocoagulation with or without secondary intraocular lens (IOL) implantation. One asymptomatic patient was observed. The postoperative visual acuity ranged from 20/20 to 20/60 in nonamblyopic eyes. Conclusions: The pathogenic homozygous c.767_786del variant in ADAMTSL4 may be a cause of bilateral isolated ectopia lentis in the Ohio Amish and Mennonite populations, likely as a result of a founder effect. Vitrectomy and lens extraction with or without secondary IOL implantation may lead to good visual outcomes. There were no cases of retinal detachment.