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This abstract is assigned to session BGS: Belgian Glaucoma Society

Title

FRO: Identity-by-descent mapping reveals a new locus for primary congenital glaucoma, GLC3E, on chromosome 19p13.2.

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 from birth or early infancy. The prevalence of PCG is estimated to be 1:10.000 in Western populations with higher prevalences in inbred populations. In general PCG displays an autosomal recessive inheritance and is genetically heterogeneous. To date, four PCG loci are known (GLC3A-D), in which two genes have been identified, CYP1B1 and LTBP2. Here, we aimed to map the disease gene in a large, four-generation consanguineous family with PCG, originating from Jordany.
Methods	Mutations in and linkage to the known PCG genes CYP1B1 and LTBP2 were excluded respectively. Homozygosity or identity-by-descent (IBD) mapping was performed in six affected members using genomewide SNP genotyping with 250K arrays (Affymetrix), followed by data analysis with a homemade Perl script.
Results	The identified IBD regions did not overlap with any known PCG loci. Filtering on both size of the region and number of consecutive homozygous SNPs revealed a new candidate region on 19p13.2, named GLC3E. This region measures 1,8 Mb and contains 57 genes. Targeted resequencing of this region is ongoing.
Conclusion	We identified a new PCG locus, named GLC3E, confirming the genetic heterogeneity of PCG, and representing a unique opportunity to identify the third PCG gene.

Author 1

Last name	VERDIN
Initials	H
Department	CMGG, Ghent University
City	Ghent

Author 2

Last name	D'Haene
Initials	B
Department	CMGG, Ghent University
City	Ghent

Author 3

Last name	Coppieters
Initials	F
Department	CMGG, Ghent University
City	Ghent

Author 4

Last name	Lefever
Initials	S
Department	CMGG, Ghent University
City	Ghent

Author 5

Last name	Kestelyn
Initials	P
Department	Dept of Ophthalmology, Ghent University Hospital
City	Ghent

Author 6

Last name	Leroy
Initials	B
Department	Dept of Ophthalmology, Ghent University Hospital
City	Ghent

Author 7

Last name	De Baere
Initials	E
Department	CMGG, Ghent University
City	Ghent