Mutations of fibrillin-1 (FBN1) have been associated with Marfan syndrome and pleiotropic connective tissue disorders, collectively termed as "type I fibrillinopathy".However, few genotype-phenotype correlations are known in the ocular system.Patients with congenital ectopia lentis (EL) received panel-based next-generation sequencing, complemented with multiplex ligation-dependent probe amplification.In a total of 125 probands, the ocular phenotypes were compared for different types of FBN1 mutations. Premature termination codons were associated with less severe EL and a thinner central corneal thickness (CCT) than the inframe mutations. The eyes of patients with mutations in the C-terminal region had a higher incidence of posterior staphyloma than those in the middle and N-terminal regions. Mutations in the TGF-β-regulating sequence had larger horizontal corneal diameters (white-towhite [WTW]), higher incidence of posterior staphyloma, but less severe EL than those with mutations in other regions. Mutations in the neonatal region were associated with thinner CCT. Longer axial length (AL) was associated with mutations in the C-terminal region or TGF-β regulating sequence after adjusting for age, EL severity, and corneal curvature radius. FBN1 genotype-phenotype correlations were established for some ocular features, including EL severity, AL, WTW, CCT, and so forth, providing novel perspectives and directions for further mechanistic studies.

Marfan syndrome (MFS, OMIM: 154700) is a heritable multisystemic disease characterized by a wide range of clinical manifestations. The underlying molecular defect is caused by variants in the FBN1. Meanwhile, FBN1 variants are also detected in a spectrum of connective tissue disorders collectively termed as ‘type I fibrillinopathies’. A multitude of FBN1 variants is reported and most of them are unique in each pedigree. Although MFS is being considered a monogenic disorder, it is speculated that the allelic heterogeneity of FBN1 variants contributes to various manifestations, distinct prognoses, and differential responses to the therapies in affected patients. Significant progress in the genotype–phenotype correlations of MFS have emerged in the last 20 years, though, some of the associations were still in debate. This review aims to update the recent advances in the genotype-phenotype correlations of MFS and related fibrillinopathies. The molecular bases and pathological mechanisms are summarized for better support of the observed correlations. Other factors contributing to the phenotype heterogeneity and future research directions were also discussed. Dissecting the genotype-phenotype correlation of FBN1 variants and related disorders will provide valuable information in risk stratification, prognosis, and choice of therapy.

<b><i>Introduction:</i></b> Marfan syndrome (MFS) is characterized by ectopia lentis (EL) and elongated axial length (AL). The characteristics of AL in young patients with MFS and bilateral EL before the lens surgery are not fully understood. <b><i>Methods:</i></b> This study reviewed MFS patients under 20 years old with bilateral EL from January 2015 to October 2020. The Z-scores were introduced in terms of the number of standard deviations from the mean of age-matched normative data. Using Z-scores, the distribution of AL and influence factors were evaluated. The correlations between AL and other biometrics were analyzed. <b><i>Results:</i></b> We reviewed 183 patients and enrolled both eyes. The mean age was 8.44 ± 4.69 years. About 36% of the patients were children under 6 years old. The median AL increased from 23.16 mm under 5 years old to 26.20 mm in the 16–20 age group, and when plotted, the trend presented a logarithmic curvature (<i>R</i>² = 0.145, <i>p</i> &#x3c; 0.001). The median Z-AL score was 1.24. One-third of eyes had Z-score &#x3c;0. About 20% of the patients had AL difference over 1 mm between the right and left eyes, and the right one had longer Z-AL scores (<i>p</i> = 0.013). The eye complicated with megalocornea (10, 7.04%) had larger Z-AL scores (4.72 ± 3.51 vs. 1.10 ± 2.25, <i>p</i> = 0.002). A positive correlation was found between Z-AL and Z-corneal curvature radius (<i>r</i> = 0.265, <i>p</i> &#x3c; 0.001). <b><i>Conclusion:</i></b> Young patients with bilateral EL but small AL should not be excluded from MFS without systematic examination. The age-adjusted Z-score will facilitate further study of the individual variations in AL across different ages.

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BackgroundMicrospherophakia (MSP) is a rare ocular condition, the lens surgery of which is complicated by both insufficient zonules and undersized capsule.MethodsThis study included MSP eyes managed with phacoemulsification combined with supra-capsular and scleral-fixated intraocular lens implantation (SCSF-IOL) and made the comparison with those treated by transscleral-fixated modified capsular tension ring and in-the-bag intraocular lens implantation (MCTR-IOL).ResultsA total of 20 MSP patients underwent SCSF-IOL, and 17 patients received MCTR-IOL. The postoperative best corrected visual acuity was significantly improved in both groups (P &lt; 0.001), but no difference was found between the groups (P = 0.326). The IOL tilt was also comparable (P = 0.216). Prophylactic Nd:YAG laser posterior capsulotomy was performed 1 week to 1 month after the SCSF-IOL procedure. In the SCSF-IOL group, two eyes (10.00%) needed repeated laser treatment and one eye (5.00%) had a decentered capsule opening. Posterior capsule opacification was the most common complication (6, 35.29%) in the MCTR group. No IOL dislocation, secondary glaucoma, or retinal detachment was observed during follow-up.ConclusionsSCSF-IOL is a viable option for managing MSP and is comparable with the MCTR-IOL. Nd:YAG laser posterior capsulotomy was necessary to prevent residual capsule complications after the SCSF-IOL procedure.

Background Isolated sulfite oxidase deficiency (ISOD) caused by sulfite oxidase gene (SUOX) mutations is a rare neurometabolic disease associated with ectopia lentis (EL). However, few genotype–phenotype correlations have been established yet. Methods Potentially pathogenic SUOX mutations were screened from a Chinese cohort of congenital EL using panel-based next-generation sequencing and analyzed with multiple bioinformatics tools. The genotype–phenotype correlations were evaluated via a systematic review of SUOX mutations within our data and from the literature. Results A novel paternal missense mutation, c.205G > C (p.A69P), and a recurrent maternal nonsense mutation, c.1200 C > G (p.Y400*), of SUOX were identified in a 4-year-old boy from 312 probands. The biochemical assays manifested elevated urine sulfite and S-sulfocysteine accompanied by decreased homocysteine in the blood. The patient had bilateral EL and normal fundus, yet minimal neurological involvement and normal brain structure. Molecular modeling simulation revealed the p.A69P mutant had an unstable structure but an unchanged affinity for sulfite, while the truncated p.Y400* mutant showed decreased binding capacity. Genotype–phenotype analysis demonstrated patients with biallelic missense mutations had milder symptoms (P = 0.023), later age of onset (P < 0.001), and a higher incidence of regression (P = 0.017) than other genotypes. No correlations were found regarding EL and other neurological symptoms. Conclusion The data from this study not only enrich the known mutation spectrum of SUOX but also suggest that missense mutations are associated with mild and atypical symptoms.

We explored the influencing factors and developed a prediction model of AL growth to optimize IOL power selection in pediatric eyes with Marfan syndrome and ectopia lentis.

ObjectiveThe aim of this study was to examine the biometric ocular manifestations and structural ocular features of anterior megalophthalmos (AM).MethodsFifteen patients with AM (30 eyes) from the Eye &amp; ENT Hospital of Fudan University were included. The age-matched control group consisted of 30 participants (30 eyes) who underwent Pentacam HR and IOLMaster 700 measurements for one normal eye. Data on demographics, biometric manifestations, and genotypes were carefully compared.ResultsA total of 15 patients with AM and 30 control patients were enrolled. There were no differences in age (37.27 ± 19.1 vs. 31.43 ± 19.69 years, P = 0.249) between these two groups. AM eyes were characterized by premature cataracts (11/30, 36.67%) and zonular weakness with lens subluxation (22/30, 73.33%) compared with the control group. Notably, 20 of the 30 AM eyes (66.67%) had significant posterior iris bowing, and 16 of the 30 AM eyes (53.33%) showed an enlarged ciliary ring on ultrasound biomicroscopy (UBM). Mean corneal curvature was lower in the AM eyes (42.01 ± 2.06 D vs. 43.14 ± 1.38 D, P = 0.023). There was no significant difference in corneal pachymetry and central endothelial cell count between the AM and control groups. Significant differences were found in terms of the anterior chamber and white-to-white (WTW) among the Pentacam HR and IOLMaster 700 in patients with AM (P &lt; 0.05). The difference was 0.53 ± 0.48 mm and 0.36 ± 0.14 mm, respectively (P &lt; 0.001).ConclusionThe results of this cohort study conclude the biometric and structural ocular manifestations in Chinese cohorts. Posterior iris bowing (66.67%) and lens subluxation (73.33%) are the most characteristic findings in patients with AM with anatomical abnormalities of megalocornea and a deep anterior chamber, although corneal biometric manifestations of AM included flatter cornea and lower total corneal astigmatism. The knowledge of ocular manifestations of AM is important for diagnosis and preparation for the operation in advance to avoid intraoperative and postoperative complications. Significant differences were found in the anterior chamber and WTW values between the Pentacam HR and IOLMaster 700. Thus, we suggest that various examinations should be carefully considered before determining an AM diagnosis.