Abstract
Purpose: :
To provide genetic consultation and presymptomatic diagnosis to the family members by investigating the genetic cause of a large primary juvenile open angle glaucoma (JOAG)pedigree with an autosomal dominant fashion. Analysis of the correlation between the phenotype and genotype helps us to understand the role of gene mutation in familial open angle glaucoma in China.
Methods: :
Ocular examinations were performed on all the members of the pedigree in order to determine their disease status. Subjects were labeled as affected, unaffected and suspects. Genomic DNA was extracted from the peripheral blood of all the family members, following standard procedure. Fragments of all the three exons of MYOC, the 12 coding exons of OPTN and 2 coding exons of CYP1B1 were amplified by polymerase chain reaction (PCR). Direct DNA sequencing was used to identify the mutation of MYOC, OPTN and CYP1B1. Presymtomatic diagnosis was made for the consulters according to the clinical examination and genetic analysis results.
Results: :
One heterozygous mutation of MYOC gene was identified in all the patients of the pedigree. That is cytosine to thymine transition at 1109th nucleotide, which results in the 370th amino acid residue changing from proline to leucine. Two teenagers, who were labeled as suspects, were detected to carry the same mutation. All the healthy members were lack of this mutation. No mutation of OPTN and CYP1B1 was found. The two mutation carriers have the very high risk of developing glaucoma while the other suspects are excluded from JOAG. Close follow–up at regular intervals is recommended.
Conclusions: :
The mutation Pro370Leu of MYOC gene contributes to JOAG in this pedigree. Early onset, rapid development and poor response to medicine are the characteristics of this mutation. In such kind of typical autosomal inheritance pedigree with JOAG, genetic analysis does help us provide genetic consumption and presymptomatic diagnosis.
Keywords: genetics • mutations