Expression of Genes and ESTs within the HBID Duplication Region in Human Conjunctival Cell Lines and Tissue

Abstract

Abstract: : Purpose: Hereditary benign intraepithelial dyskeratosis (HBID) is an autosomal dominant cell proliferation disorder characterized by opaque epithelial plaques of the conjunctiva and oral mucosa. Found primarily among a Native American tribe in North Carolina and their relatives, HBID plaques appear at birth or in early childhood. Involvement typically includes the conjunctiva, cornea, and buccal mucosa. Loss of vision secondary to corneal involvement can occur. This disorder has been linked to chromosome 4q35 and a near–telomeric DNA duplication in this region (Allingham RR, et al. Am J Hum Genet 2001). Genes within this region may play a role in the pathogenesis of HBID. We therefore examined the expression of genes and ESTs within a region of 4q35 associated with HBID. Methods: Multiple bioinformatics approaches were used to identify possible exons in the 4q telomeric region. Primers were designed to experimentally verify each exon and test expression in a variety of tissues. Total RNA was extracted from the following sources: a normal conjunctival (CCj) cell line, a HBID ocular lesion (HCj) cell line, normal conjunctival tissue, and HBID ocular lesion tissue. First strand cDNA synthesis was performed on these RNAs as well as on RNA from a commercially available panel of total RNA. Polymerase chain reaction (PCR) was performed and products were resolved on agarose gels. In addition, real time PCR was performed using TaqMan assays for various 4q35 genes. Results: The expression of 4q35 genes within the region associated with HBID was detected in human conjunctival cell lines and tissue. Certain genes and ESTs within this region were not expressed in conjunctival cell lines and tissue, but were expressed in other tissues, such as salivary gland and uterus. All genes/ESTs were expressed in at least one tissue examined. Conclusions: These results provide information on which 4q35 genes, predicted genes, and ESTs are expressed in normal conjunctival cells and tissue and in HBID lesions. This information will aid us in selecting candidate genes for further study in HBID.

Keywords: conjunctiva • genetics • gene/expression