Identification of novel disease gene for primary congenital glaucoma (PCG) through homozygosity mapping and next-generation sequencing strategies in a large consanguineous pedigree

Purpose Primary congenital glaucoma (PCG) is caused by developmental anomalies of the trabecular meshwork and the anterior chamber angle resulting in an increased ocular pressure (IOP) and optic nerve damage. In general PCG displays an autosomal recessive inheritance pattern and is genetically heterogeneous. To date, three PCG loci are known, namely GLC3A, GLC3B and GLC3C, and two causal genes have been identified, CYP1B1 located in the GLC3A locus and LTPB2 located at 1.3 MB proximal to the GLC3C locus. The purpose of the current study is to identify the causal disease gene in a large consanguineous family with PCG, originating from Jordany. CYP1B1 mutations and linkage to the LTBP2, GLCB3 and GLCC3 locus were previously excluded. Methods In a first step, DNA from members from the consanguineous family will be genotyped by 250K GeneChip Mapping Affymetrix arrays. Homozygosity mapping will be applied to identify potential disease loci, using a homemade Perl script. Next, microsatellite analysis will be performed in order to confirm findings and to narrow down candidate regions. Subsequently, candidate regions of interest will be captured (Agilent) and sequenced on the Illumina Genome Analyser IIx (GAIIx). Gene and variant prioritization will be done using in-house developed software, followed by segregation analysis and screening in control individuals. At last, a cohort of 30 molecularly unsolved PCG patients will be screened for mutations in the newly identified disease. Conclusion The identification of a new disease gene for PCG may lead to better insights into the molecular pathogenesis of glaucoma, and might uncover novel therapeutic strategies.