Abstract
Abstract: :
Purpose:To identify the underlying genetic defect in Egyptian and Saudi Arabian patients with primary congenital glaucoma (PCG). Mutation screening of cytochrome P4501B1 gene (CYP1B1, OMIM 601771) was undertaken. Methods: A clinical and genetic study was performed on one Saudi Arabian Family, 6 Egyptian families, and 4 Egyptian sporadic cases with PCG. Clinical diagnosis was confirmed by slit lamp biomicroscopy, measurement of intra ocular pressure (IOP) and corneal diameter, and gonioscopy. Molecular genetic study was performed on 22 DNA samples from 12 probands and their relatives. The coding region of CYP1B1 gene was amplified by polymerase chain reaction (PCR) using primers located in the flanking intron and untranslated sequences. For mutation detection, direct sequence analysis was performed using the ABI 3100 automated sequencer. Results:Two mutations were identified in four of our patients. One, E173K, was novel and was detected in a single Egyptian family. The other, G61E previously reported in patients from different ethnic origins, was detected in 2 of the Egyptian families and in the Saudi Arabian family. The novel change was not detected in 100 control chromosomes. Meanwhile it was located in a region which was highly conserved and might disrupt the helical structure of the protein. In addition, 6 single nucleotide polymorphisms (SNPs) (IVS1–12C>T, R48G, A119S, V432L, D442D, and N453S), previously reported, were also identified. No pathological changes were detected in 3 families and 4 sporadic Egyptians. Conclusions: This is the first report of CYP1B1 gene mutation screening in Egyptian population. The novel mutation detected could be specific to the Egyptian population and may result in a deleterious effect on the protein structure encoded by the gene. Affected patients who showed no mutations in the coding region of CYP1B1 should be subjected to further examination of the untranslated regions of the gene and/or MYOC and PITX2 genes screening.
Keywords: gene screening • genetics • mutations