Primary open-angle glaucoma (POAG) is a complex disease with unknown causes. However, in the past decade, POAG has been linked to six chromosomal regions, of which the gene MYOC encoding myocilin and the gene OPTN encoding optineurin have been identified to harbor causal mutations (disease-causing variants, DCV). POAG caused by DCV at MYOC has been termed "myocilin glaucoma". Clinically, DCV at MYOC may manifest as a typical POAG, normal tension glaucoma, or ocular hypertension without glaucoma. Individuals with the Arg46Stop mutation that almost knocks out the entire coding sequence may have severe glaucoma or no glaucoma. Genetically, myocilin glaucoma follows autosomal dominant, recessive or no pattern of inheritance. DCV at MYOC cause POAG in interaction with environmental factors and DCV at other loci. Most DCV at MYOC are relatively young, and the Gln368Stop mutation is exclusively European in origin. The overall frequency of DCV at MYOC is similar among African, Caucasian and Asian probands with POAG. Because of this fact and the higher prevalence of POAG in African descendants compared with Caucasians or Asians, the overall frequency of DCV at MYOC is several-fold higher in the general population of African descendants, which is in part responsible for their higher prevalence of POAG. Although the Arg46Stop mutation was often observed in normal controls, Arg46Stop carriers tend to have higher risk of developing POAG. Polymorphisms at several loci including MYOC are associated with POAG, and play an important role in the pathogenesis of POAG.
Prostate cancer (PC) has the highest degree of genetic transmission of any form of malignancy. In some families, the hereditary pattern is so strong as to mimic an autosomal dominance trait. We reviewed the known predisposing genetic markers to assess possible strategies for screening of families at risk. We carried out a systematic literature search using the Pubmed service of the National Center for Biotechnology Information (NCBI) and several gene libraries, including the NCBI SNP Library, the Online Mendelian Inheritance in ManV R Catalog of Human Genes and Genetic Disorders (OMIM) and SNPedia to obtain known gene loci, SNPs and satellite markers associated with PC. We further cross referenced information on identified loci comparing data from different articles and gene reference sites. Whenever possible, we recorded the odds ratio (OR) for the allele associated with PC. In multiple different linkage studies, many independent PC associated loci have been identified on separate chromosomes. Genome-wide association studies have added many more markers to the set derived from linkage investigations. A subset of the alleles is associated with early onset and aggressive cancer. Due to the great heterogeneity, the OR for any one allele predicting future development of this malignancy is low. The strongest predictors are the BRCA2 mutations, and the highly penetrant G84E mutation in HOXB13. The presence of multiple risk alleles is more highly predictive than a single allele. Technical limitations on screening large panels of alleles are being overcome. It is appropriate to begin supplementing prostate specific antigen testing with alleles, such as BRCA2 and HOXB13, disclosed by targeted genomic analysis in families with an unfavorable family cancer history. Future population studies of PC should include genomic sequencing protocols, particularly in families with a history of PC and other malignancies.
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