Myopia, or nearsightedness, is a condition in which the eye cannot focus on distant objects and sometimes closer ones too. In past different authors reported different loci responsible for myopia. They used specifically synthesized markers for different loci and after conducting linkage analysis through genotyping the myopic families were found to be linked for those loci, whereas, in some studies the cause of myopia was environmental. Till now, linkage studies have identified at least 18 possible loci in 15 different chromosomes associated with myopia, although some of these remain to be confirmed. In past, no study was done in Pakistan on myopic families for finding responsible myopic locus in this regard. So, more conclusive and well-designed studies on family pedigrees of individuals with high myopia were needed to be conducted in Pakistan by using genetic markers associated with myopia.

In this study, a panel of microsatellite markers was developed. Blood samples were taken from six myopic families. DNA was extracted. PCR was performed for amplification of these I microsatellite markers on 34 samples belonging to 6 families. Genotyping analysis was performed for the PCR products of microsatellite markers. These results were studied by constructing and analyzing haplotypes on the basis of PAGE gel bands. Heterozygosity, homozygosity, polymorphism with all microsatellites markers, specific for two loci were checked.

One family MYO-4 was found to be potentially linked with markers for the locus MYP-18. Another family MYO-5 showed potential linkage for the locus 2q37.2. Remaining four families (MYO-l, MYO-2, MYO-3 and MYO-6) were totally unlinked with all the markers (D14S984, D14S63, D14S999, D2S2202, D2S2968 and D2S338 for both loci demonstrating genetic insusceptibility of myopic loci in developing myopia and thus suggesting the complex genetic variability of myopia.

This study will serve as the pioneering database for further research on identifying the genetic heterogenic complexity of myopia. Results of this study lead to development of a panel of microsatellite markers which can be used for linkage studies of more myopic families in Pakistan. This study opens the door for new geneticists as the results can also be helpful in carrying out genetic counseling for the myopic persons who are going to be married and specifically for those who have dominant inheritance. This was a preliminary study on myopic patients in Pakistan and data produced during this study will be helpful for drawing and determining genetic inheritance of expected babies with affected parents and siblings. Moreover this study can become the basis for further research investigations on myopics in Pakistan.

CONCLUSION

This was a pioneering study to develop panel of microsatellite markers for conducting linkage analysis and genetic characterization of myopic patients in Pakistan. As a result of this successful study a reliable, efficient and very informative panel of microsatellite markers was successfully developed which was capable to interpret individual diseased allelic identity, to be used for conducting linkage analysis through genotyping of myopics in Pakistan. This study will serve as the database for further research on identifying the genetic heterogenic complexity of myopia and also these successful results can be further analyzed in future on more myopics from different areas of Pakistan. This work provokes the need for further research purposes in identifying the genes influencing myopia that could help develop targeted treatments for children who are genetically predisposed to developing myopia.