Whole-Exome Sequencing of Congenital Glaucoma Patients Reveals Hypermorphic Variants in GPATCH3, a New Gene Involved in Ocular and Craniofacial Development

Abstract

Congenital glaucoma (CG) is a heterogeneous, inherited and severe optical neuropathy that originates from maldevelopment of the anterior segment of the eye. To identify new disease genes, we performed whole-exome sequencing of 26 unrelated CG patients. In one patient we identified two rare, recessive and hypermorphic coding variants in GPATCH3, a gene of unidentified function, and 5% of a second group of 170 unrelated CG patients carried rare variants in this gene. The recombinant GPATCH3 protein activated in vitro the proximal promoter of CXCR4, a gene involved in embryo neural crest cell migration. The GPATCH3 protein was detected in human tissues relevant to glaucoma (e.g., ciliary body). This gene was expressed in the dermis, skeletal muscles, periocular mesenchymal-like cells and corneal endothelium of early zebrafish embryos. Morpholino-mediated knockdown and transient overexpression of gpatch3 led to varying degrees of goniodysgenesis and ocular and craniofacial abnormalities, recapitulating some of the features of zebrafish embryos deficient in the glaucoma-related genes pitx2 and foxc1. In conclusion, our data suggest the existence of high genetic heterogeneity in CG and provide evidence for the role of GPATCH3 in this disease. We also show that GPATCH3 is a new gene involved in ocular and craniofacial development.

CPAMD8 loss-of-function underlies non-dominant congenital glaucoma with variable anterior segment dysgenesis and abnormal extracellular matrix

“…In accordance with our previous studies, the finding of a large proportion (14%) of CG patients carrying infrequent heterozygous CPAMD8 variants also provides evidence for the role of CPAMD8 in non-monogenic or complex congenital glaucoma, reflecting the notions that it participates in the complex genetic regulation of ocular development, and that the combination of genetic defects in more than one of these genes may contribute to the abnormal development of the anterior segment of the eye (Ferre-Fernández et al 2017;López-Garrido et al 2013).…”

“…1A and 3A. The DNA sample for WES was processed as previously described (Ferre-Fernández et al 2017). Candidate variants identified by NGS were verified and segregated in the corresponding families by Sanger sequencing following PCR amplification using conditions and primers indicated Table S1.…”

“…The first identified and most prevalent cause of recessive PCG is CYP1B1 loss-of-function (LoF) (Sarfarazi and Stoilov 2000;Stoilov et al 1997), which is present in 18%-48% of non-consanguineous European patients (Campos-Mollo et al 2009;Colomb et al 2003;López-Garrido et al 2013;Weisschuh et al 2009). Additional genes reported to play a role in this pathology are LTBP2 (Ali et al 2009), MYOC (Kaur et al 2005), FOXC1 (Medina-Trillo et al 2016;Medina-Trillo et al 2015), TEK (Souma et al 2016) and GPATCH3 (Ferre-Fernández et al 2017), illustrating the genetic heterogeneity of this disease.…”

Role of <em>GUCA1C </em>in Primary Congenital Glaucoma and in the Retina: Functional Evaluation in Zebrafish

“…Mini Kit (Quiagen) and processed for NGS as previously described [14]. Candidate disease-causing variants were identified through the application of a multistep filtering approach.…”

“…Rare variants in the angiopoietin receptor TEK (TEK, MIM# 600221) likely underlie dominant PCG with variable expressivity in some patients [13]. Additionally, rare hypermorphic G-PATCH DOMAIN-CONTAINING PROTEIN 3 (GPATCH3, MIM# 617486) variants have been reported in some cases [14]. The presence of disease-causing variants in other genes such as MYOCILIN (MYOC, MIM# 601652) [15,16] and FORKHEAD BOX C1 (FOXC1, MIM# 601090) [17,18], have also been described in a few patients.…”