Novel p.G1344E mutation in FBN1 is associated with ectopia lentis

Novel compound heterozygous variants in LTBP2 associated with relative anterior microphthalmos

PURPOSE

Relative anterior microphthalmos (RAM) is a rare congenital defect associated with severe vision impairment that is primarily caused by genetic alterations. The purpose of this study was to identify the causative genetic variants in two Chinese families with RAM with an autosomal recessive inheritance pattern.

METHODS

DNA samples were obtained from two probands and their family members. Targeted next-generation sequencing (NGS) was used to screen 425 genes associated with inherited eye diseases to identify possible disease-causing variants in the two patients. Sanger sequencing was subsequently used to validate the results in both families.

RESULTS

The targeted NGS panel identified potentially causative novel variants of the latent transforming growth factor beta binding protein 2 (LTBP2) gene in the two RAM families: a missense variant (c.2771C > T; p.Ala924Val) and an intronic variant (c.4582 + 9A > G) in Family A and a different missense variant (c.5239C > A; p.Arg1747Ser) and a synonymous variant (c.951G > A; p.Pro317Pro) in Family B. These four novel variants all cosegregated with the disease phenotype.

CONCLUSION

To our knowledge, this is the first study to report novel LTBP2 gene variants related to RAM. Considering the importance of LTBP2 in ocular development, we provide initial insights into the potential pathogenic mechanisms of LTBP2 in RAM.

Clinical characteristics and diagnostic test for spherophakia: A retrospective analysis

Background

This study aimed to analyze ocular characteristics in patients diagnosed with spherophakia, establish effective diagnostic criteria, and aid clinicians in prompt identification and management.

Methods

A retrospective case series identified spherophakia cases through medical records and literature searches. The case group included spherophakia patients, and the control group comprised individuals with similar eye conditions. Intraocular lens calculations used the SRK-T formula, and statistical analyses were performed using SPSS. Diagnostic efficacy was assessed through receiver operating characteristic (ROC) curve analysis.

Results

The study included 12 cases (23 eyes) from medical records and 86 patients (142 eyes) from literature sources. Characteristics of spherophakia included bilateral involvement, younger age, shallow anterior chamber depth, lens dislocation, and secondary glaucoma. A diagnostic criterion based on lens power demonstrated high sensitivity (94.3 %) and specificity (91.9 %). ROC analysis yielded area under the ROC curve (AUROC) values of 0.974 for lens power, outperforming refractive error (0.119), corneal curvature (0.465) and axial length (0.496). The lens power cutoff for diagnosing spherophakia was 31.25D.

Conclusion

The study offers crucial insights into spherophakia's clinical characteristics and presents a practical diagnostic criterion using lens power, enhancing early detection and management. Further research is needed to validate and refine these findings, establishing standardized diagnostic criteria for spherophakia.

Genetic mutation and aqueous humor metabolites alterations in a family with Marfan syndrome

This study used four generations of a Chinese family to reveal the genetic etiology and ocular manifestation pathogenesis of Marfan syndrome (MFS) through whole genome sequencing (WGS) and metabolomics analysis. In the study, we explored the pathogenic gene variant and aqueous humor (AH) metabolites alterations of MFS. Using WGS, a novel heterozygous variant (NM_000138: c.G4192A, p.D1398 N) in the fibrilin-1 (FBN1) gene was identified. This variant was co-segregated with the phenotype and considered "deleterious" and highly conserved during evolution. The p.D1398 N variant is located in a cbEGF-like domain and predicted to lead to a new splice site, which might result in structural and functional changes to the FBN1 protein. FBN1 is highly expressed in the mouse cornea, conjunctiva and lens capsule, which highlights the important role of FBN1 in eyeball development. AH metabolomics analysis identified eight differentially expressed metabolites, including 3-hydroxyphenylacetic acid, 4-pyridoxic acid, aminoadipic acid, azelaic acid, chlordiazepoxide, niacinamide, ribose, 1,5-bisphosphate and se-methylselenocysteine, associated with relevant metabolic pathways likely involved in the pathogenesis of ocular symptoms in MFS. Our analysis extends the existing spectrum of disease-causing mutations and reveals metabolites information related to the ophthalmic features of MFS. This may provide a new sight and a basis for the diagnosis and mechanism of MFS.

De Novo Mutations Contributes Approximately 7% of Pathogenicity in Inherited Eye Diseases

Purpose

The purpose of this study was to describe genotype-phenotype associations and novel insights into genetic characteristics in a trio-based cohort of inherited eye diseases (IEDs).

Methods

To determine the etiological role of de novo mutations (DNMs) and genetic profile in IEDs, we retrospectively reviewed a large cohort of proband-parent trios of Chinese origin. The patients underwent a detailed examination and was clinically diagnosed by an ophthalmologist. Panel-based targeted exome sequencing was performed on DNA extracted from blood samples, containing coding regions of 792 IED-causative genes and their flanking exons. All participants underwent genetic testing.

Results

All proband-parent trios were divided into 22 subgroups, the overall diagnostic yield was 48.67% (605/1243), ranging from 4% to 94.44% for each of the subgroups. A total of 108 IED-causative genes were identified, with the top 24 genes explaining 67% of the 605 genetically solved trios. The genetic etiology of 6.76% (84/1243) of the trio was attributed to disease-causative DNMs, and the top 3 subgroups with the highest incidence of DNM were aniridia (n = 40%), Marfan syndrome/ectopia lentis (n = 38.78%), and retinoblastoma (n = 37.04%). The top 10 genes have a diagnostic yield of DNM greater than 3.5% in their subgroups, including PAX6 (40.00%), FBN1 (38.78%), RB1 (37.04%), CRX (10.34%), CHM (9.09%), WFS1 (8.00%), RP1L1 (5.88%), RS1 (5.26%), PCDH15 (4.00%), and ABCA4 (3.51%). Additionally, the incidence of DNM in offspring showed a trend of correlation with paternal age at reproduction, but not statistically significant with paternal (P = 0.154) and maternal (P = 0.959) age at reproduction.

Conclusions

Trios-based genetic analysis has high accuracy and validity. Our study helps to quantify the burden of the full spectrum IED caused by each gene, offers novel potential for elucidating etiology, and plays a crucial role in genetic counseling and patient management.

Correlation between novel compound heterozygous ADAMTSL4 variants and primary phenotypes of ectopia lentis et pupillae

PURPOSE

To investigate molecular pathogenesis of congenital ectopia lentis accompanied by various ophthalmic manifestations in a pedigree.

METHODS

Three female siblings, their spouse and offspring underwent ophthalmic and general medical examinations. Genetic variants were screened with the whole exome sequencing and analyzed in either a dominant or recessive inheritance manner. Gene mutations were ascertained with the Sanger sequencing after the polymerase chain reaction.

RESULTS

All three female siblings were diagnosed as the Ectopia lentis et pupillae (ELeP) through combination of clinical examination and genetic analysis. No characteristic pathological changes of skeletal, metabolic and cardiac abnormalities were observed. Thirteen genetic variants were selected out through analyzing in the dominant or recessive inheritance manner, but they were not associated with EL. Among them, ALOX15B variant may explain the skin disease in this pedigree. After inspection the known genes related to EL, novel compound heterozygous mutations (p.Ser264LeufsX37/p.Gly757ValfsX62) in ADAMTSL4 were discreetly identified in this ELeP pedigree.

CONCLUSIONS

Novel compound heterozygous ADAMTSL4 variants are responsible for ELeP in the current pedigree. Correlation between ADAMTSL4 variants and ELeP was firstly established based on our 12 years follow-up studies and previous reports of ELeP and of ADAMTSL4-related eye disorders. The primary phenotypes caused by ADAMTSL4 variants include EL, EP, poor pupillary dilation, and axial elongation. Highly varying phenotypes including glaucoma, high myopia retinapathy, and poor vision and so on may be the secondary impairments. All these secondary impairments may be improved if proper clinical interventions are implemented in time.