Axenfeld-Rieger Anomaly

Genotype-phenotype association of PITX2 and FOXC1 in Axenfeld-Rieger syndrome

PITX2 and FOXC1 are the most common pathogenic genes associated with Axenfeld-Rieger syndrome (ARS). In this study, we aimed to explore the variation spectrum of PITX2 and FOXC1 and their associated phenotype based on data from our study and previously reported literatures. Whole exome sequencing was performed on eight probands in our study. Multistep bioinformatic and co-segregation analyses were performed to detect pathogenic variants. Genotype-phenotype correlations of PITX2 and FOXC1 and the differences between them were determined. We detected three variants of FOXC1 and two variants of PITX2 in five unrelated families with ARS. Macular retinoschisis had been observed in AR1 with variant in PITX2 and it is not reported before. Additionally, a review of published literature and our study led to the identification of 593 families with variants of PITX2 or FOXC1, including 316 families with heterozygous variants in FOXC1, 251 families with heterozygous variants in PITX2, 13 families with variants in double genes, seven families with homozygous or compound heterozygous variants in FOXC1, and six families with variants in ADAMTS17, PRDM5, COL4A1 or CYP1B1. Significant differences were observed between the prevalence of missense and in-frame, truncation, and large deletion variants in PITX2 (32.00%, 42.67%, and 25.33%, respectively) and FOXC1 (34.49%, 35.13%, 30.38%, respectively) (p = 1.16E-43). Enrichment and frequency analyses revealed that missense variants were concentrated in the forkhead domain of FOXC1 (76.14%) and homeodomain of PITX2 (87.50%). The percentage of Caucasians with variants in FOXC1 was significantly higher than that of PITX2 (p = 2.00E-2). Significant differences between PITX2 and FOXC1 were observed in glaucoma (p = 3.00E-2), corectopia (p = 3.050E-6), and polycoria (p = 5.21E-08). Additionally, we observed a significant difference in best-corrected visual acuity (BCVA) between FOXC1 and PITX2 (p = 3.80E-2). Among all the family members with PITX2 or FOXC1 variants, the prevalence of systemic abnormalities was significantly higher in PITX2 than in FOXC1 (89.16% vs. 58.77%, p = 5.44E-17). In conclusion, macular retinoschisis as a novel phenotype had been observed in patient with variant in PITX2. Significant differences were detected in phenotypes and genotypes between PITX2 and FOXC1.

Childhood glaucoma genes and phenotypes: Focus on FOXC1 mutations causing anterior segment dysgenesis and hearing loss

Childhood glaucoma is an important cause of blindness world-wide. Eleven genes are currently known to cause inherited forms of glaucoma with onset before age 20. While all the early-onset glaucoma genes cause severe disease, considerable phenotypic variability is observed among mutations carriers. In particular, FOXC1 genetic variants are associated with a broad range of phenotypes including multiple forms of glaucoma and also systemic abnormalities, especially hearing loss. FOXC1 is a member of the forkhead family of transcription factors and is involved in neural crest development necessary for formation of anterior eye structures and also pharyngeal arches that form the middle ear bones. In this study we review the clinical phenotypes reported for known FOXC1 mutations and show that mutations in patients with reported ocular anterior segment abnormalities and hearing loss primarily disrupt the critically important forkhead domain. These results suggest that optimal care for patients affected with anterior segment dysgenesis should include screening for FOXC1 mutations and also testing for hearing loss.

Forkhead box C1 promotes colorectal cancer metastasis through transactivating ITGA7 and FGFR4 expression

Metastatic colorectal cancer (CRC) is one of the most common causes of cancer death worldwide; however, the molecular mechanism underlying CRC metastasis remains unknown. Using an integrated approach, we identified forkhead box C1 (FOXC1) as a novel regulator of CRC metastasis. Elevated expression of FOXC1 is significantly correlated with metastasis, recurrence and reduced survival. FOXC1 overexpression promotes CRC invasion and lung metastasis, whereas FOXC1 knockdown has the opposite effect. In addition, FOXC1 directly binds its target genes integrin α7 (ITGA7) and fibroblast growth factor receptor 4 (FGFR4) and activates their expression. Genetic epistasis analysis confirmed that ITGA7 and FGFR4 act downstream of FOXC1. Furthermore, pharmaceutical inhibition of FGFR4 can reverse CRC metastasis mediated by FOXC1 overexpression. These results suggest that FOXC1 is a prognostic biomarker in CRC patients and targeting the FGFR4 signaling pathway may provide a promising strategy for the treatment of FOXC1-driven CRC metastasis.

FOXC1, the new player in the cancer sandbox

In recent years, rapidly accumulating evidence implicates forkhead box C1 (FOXC1) in cancer, especially in studies of basal-like breast cancer (BLBC). Other studies have followed suit, demonstrating that FOXC1 is not only a major player in this breast cancer subtype, but also in hepatocellular carcinoma (HCC), endometrial cancer, Hodgkin's lymphoma (HL), and non-Hodgkin's lymphoma (NHL). The FOXC1 gene encodes a transcription factor that is crucial to mesodermal, neural crest, and ocular development, and mutations found in FOXC1 have been found to cause dominantly inherited Axenfeld-Rieger Syndrome (ARS). Interestingly, while FOXC1 missense mutations that are associated with ARS usually reduce gene activity, increased FOXC1 function now appears to be often linked to more aggressive cancer phenotypes in BLBC, HCC, HL, and NHL. This review discusses not only the role of FOXC1 in cancer cell progression, proliferation, differentiation, and metastasis, but also the underlying mechanisms of how FOXC1 can contribute to aggressive cancer phenotypes.

Demographic features of subjects with congenital glaucoma

Context:

Congenital glaucoma is a potentially blinding ocular disease of the childhood. Identification of the possible associated risk factors and may be helpful for prevention or early detection of this public health problem.

Aims:

To demonstrate the demographic features of congenital glaucoma subjects.

Setting and Design:

The charts of congenital glaucoma patients referred to Tamcelik Glaucoma Center were retrospectively reviewed through the dates of 2000 and 2013.

Materials and Methods:

Analyzed data included diagnosis, age at first presentation, symptoms at first presentation, laterality of the disease, sex, presence of consanguinity, family history of congenital glaucoma, maturity of the fetus at delivery, and maternal age at conception.

Statistical Analysis Used:

Statistical Package for Social Sciences (SPSS) version 19.0 by IBM (SPSS Inc, Chicago, Illinois, USA) was used to compare the mean of continuous variables with Student's t-test and analysis of variance (ANOVA) and χ² test was used to test differences in proportions of categorical variables.

Results:

The data of 600 eyes of 311 patients were analyzed. The distribution of primary and secondary congenital glaucoma among the patients were 63.3% (n = 197) and 36.7% (n = 114), respectively. Of the 311 patients, 57.2% (n = 178) were male and 42.8% (n = 133) were female. The overall frequency of bilateral disease was 92.3% (n = 287). Overall rate of consanguinity and positive family history was 45.3% (n = 141) and 21.2% (n = 66), respectively.

Conclusions:

Bilateral disease in this study was more common than previously reported studies. Positive family history was more frequent in primary congenital glaucoma although not statistically significant.

FOXC1, a target of polycomb, inhibits metastasis of breast cancer cells

Polycomb group (PcG) proteins have recently been shown related to cancer development. The PcG protein EZH2 is involved in progression of prostate and breast cancers, and has been identified as a molecular marker in breast cancer. Nevertheless, the molecular mechanism by which PcG proteins regulate cancer progression and malignant metastasis is still unclear. PcG proteins methylate H3K27 in undifferentiated epithelial cells, resulting in the repression of differentiation genes such as HOX. FOXC1 is a member of the Forkhead box transcription factor family, which plays an important role in differentiation, and is involved in eye development. We discovered in this study that the expression of FOXC1 gene was negatively correlated to that of PcG genes, i.e., Bmi1, EZH2, and SUZ12, in MCF-7 and MDA-MB-231 cells. To investigate the regulatory effects of PcG proteins on FOXC1 gene, the two cell lines were transfected with either expression plasmids or siRNA plasmids of Bmi1, EZH2, and SUZ12, and we found that PcGs, especially EZH2, could repress the transcription of FOXC1 gene. Chromatin immunoprecipitation (ChIP) assay showed that histone methylation and acetylation modifications played critical roles in this regulatory process. When FOXC1 was stably transfected into MDA-MB-231 cells, the migration and invasion of the cells were repressed. Moreover, the tumorigenicity and the spontaneous metastatic capability regulated by FOXC1 were determined by using an orthotropic xenograft tumor model of athymic mice with the FOXC1-MDA-MB-231HM and the GFP-MDA-MB-231HM cells, and the results showed that FOXC1 in MDA-MB-231HM cells inhibited migration and invasion in vitro and reduced the pulmonary metastasis in vivo. Data presented in this report contribute to the understanding of the mechanisms by which EZH2 participates in tumor development.

Rieger's Anomaly and Other Ocular Abnormalities in Association with Osteogenesis Imperfecta and aCOL1A1Mutation

A patient with osteogenesis imperfecta (OI) and some features of Ehlers-Danlos syndrome had Rieger's anomaly and other associated ocular abnormalities. He carried a COL1A1 mutation (c.3313delA) that has only rarely been seen in OI. The association of ocular anterior chamber abnormalities with OI has not been reported previously, while OI with Ehlers-Danlos syndrome features has only been described in some kindreds. The patient had serious complications as a result of his ocular anomalies. We speculate that the course of his disease and, perhaps, its co-existence with OI could be exacerbated by his collagen type-I defect, although no causality can be established by this report of a single case.

A novel mutation in the FOXC1 gene in a family with Axenfeld-Rieger syndrome and Peters' anomaly

Peters anomaly and Axenfeld-Rieger syndrome (ARS) belong to the overlapping spectrum of disorders summarized as anterior segment dysgenesis (ASD). Five patients from a family with Peters' anomaly and ARS were screened for mutations in the PITX2, CYP1B1 and FOXC1 genes by direct sequencing. All affected family members examined were heterozygous for a single nucleotide substitution, resulting in a nonsense mutation (Q120X) at a highly conserved residue of the FOXC1 gene that is essential for DNA binding. In this pedigree, all affected family members were diagnosed with ARS except for one who shows bilateral Peters' anomaly. Our findings support the role of FOXC1 mutations in the spectrum of ASD.

A novel PITX2 mutation and a polymorphism in a 5-generation family with Axenfeld-Rieger anomaly and coexisting Fuchs' endothelial dystrophy

PURPOSE

To investigate the clinical and genetic appearance of Axenfeld-Rieger anomaly or syndrome (ARAS) and Fuchs' endothelial dystrophy (FED) in a 5-generation pedigree coexpressing both pathologic features in a large number of family members.

DESIGN

Observational case-control and DNA linkage and screening study.

PARTICIPANTS

Of 114 family members, 50 underwent clinical investigation and DNA analysis between July 2001 and March 2004.

METHODS

Linkage at the PITX2 locus was demonstrated using a number of microsatellites mapping to the critical region 4q25 to 4q26. The PITX2 gene was subsequently screened for mutations in all investigated family members.

MAIN OUTCOME MEASURE

Linkage of the ARAS and FED phenotype and mutation detection in the PITX2 gene.

RESULTS

Twenty-seven patients were identified as being affected by ARAS. Fuchs' endothelial dystrophy was found in 19 patients. Fifteen patients presented both kinds of anomaly. Deoxyribonucleic acid sequencing revealed 2 heteroallelic DNA variants that segregated together (on the same allele) and were present in all severely affected ARAS individuals. The first variant, g.20913G>T, assumed to be the causative mutation for ARAS, causes amino acid substitution at codon 137 (G137V). A statistically significant 2-point logarithm of the odds score of 4.06 was obtained with marker D4S406. The second variant is likely a polymorphism in the intron between exons 2 and 3 (IVS2+8delCinsGTT) and was detected in heterozygous form in 20% of control individuals.

CONCLUSION

This gene analysis revealed a novel PITX2 mutation and a polymorphism in a family with ARAS. Whether FED, also manifested in the severely affected individuals, is due to a different but cosegregating gene is to be determined.

Strabismus and amblyopia in bilateral Peters anomaly

BACKGROUND

Peters anomaly is a rare form of anterior segment dysgenesis in which abnormal cleavage of the anterior chamber occurs at the end of the third week of gestation. We examined the prevalence of strabismus and amblyopia and analyzed predictive factors for their development, as well as the visual outcome and associated anomalies in patients with bilateral Peters anomaly.

METHODS

Using a retrospective review, we identified 25 consecutive patients with bilateral Peters anomaly who were observed between August 1995 and February 2005. Ocular structural and systemic anomalies, amblyopia therapy, visual acuity, and binocular alignment at last visit were recorded. Fisher's exact test was used to identify any association between defined predictive factors and the development of strabismus.

RESULTS

Mean follow-up time was 5.1 year (range, 0.5-21 years). Median age at presentation was 2.5 months (range, 1 day to 13 years). Penetrating keratoplasties were performed on 34 eyes in 20 patients. Final best-corrected visual acuity ranged from 20/25 to no light perception. Thirteen of 18 patients with recorded motility (72%) developed strabismus: esotropia (n = 7), exotropia (n = 5), and variable (n = 1); one also had dissociated vertical deviation. Patients with equal vision were either orthophoric (n = 4) or had intermittent esotropia (n = 1), whereas strabismus occurred in 100% of patients whose vision was asymmetric by more than 1.5 octaves. Asymmetric vision was the only statistically significant predictive factor for the development of strabismus (P = 0.002). Amblyopia treatment resulted in improved vision in 3 of 5 patients.

CONCLUSION

Strabismus occurs frequently in bilateral Peters anomaly. Asymmetric vision, (because of ocular structural anomalies) postoperative complications, and amblyopia may predispose to strabismus. Despite ocular structural limitations, amblyopia therapy is recommended in the aggressive rehabilitation of these eyes.