Modifications to exon amplification have been instituted that increase its speed, efficiency and reliability. Exons were isolated from target human or mouse genomic DNA sources ranging from 30 kilobases (kb) to 3 megabases (Mb) in complexity. The efficiency was dependent upon the amount of input DNA, and ranged from isolation of an exon for every 20 kb to an exon for every 80 kb of target genomic DNA. In these studies, several novel genes and a smaller number of genes isolated previously that reside on human chromosome 9 have been identified. These results indicate that exon amplification is presently adaptable to large scale isolation of exons from complex sources of genomic DNA.

Purpose of review Ocular surface squamous neoplasia (OSSN) in sub-Saharan countries is an aggressive tumor that affects younger patients and appears to be increasing in incidence. There are data to suggest the association of this disease with solar radiation exposure, HIV, and human papilloma virus (HPV). This trend possibly reflects the association of the high incidence of HIV, concomitant high incidence of exposure to HPV, and the solar radiation exposure that people in this region of the world receive. We undertook a PubMed search with the terms ‘ocular surface squamous neoplasia’, ‘conjunctival carcinoma’, ‘HIV’ and ‘HPV’, and ‘sub-Saharan/Africa’ to ascertain the scope of the problem and to review the available data, with an emphasis on publications of 2009 and the first quarter of 2010. Recent findings There is increasing evidence of a significant association between HIV seropositivity and OSSN. The role of HPV as contributing to the cause of OSSN is being investigated. Summary Patients with conjunctival cancer in sub-Saharan Africa are typically younger and more than 50% have underlying HIV infection. Initial presentation can be asymptomatic; however, many of these patients have advanced disease before they seek medical help and OSSN appears to have a more aggressive clinical course in sub-Saharan Africa. Treatment in Africa is primarily surgical. Chemotherapy and antiviral agents have been used. A diagnosis of OSSN in younger patients in sub-Saharan Africa should prompt HIV serotesting.

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To accomplish large-scale identification of genes from a single human chromosome, exon amplification was applied to large pools of clones from a flow-sorted human chromosome 22 cosmid library. Sequence analysis of more than one-third of the 6400 cloned products identified 35% of the known genes previously localized to this chromosome, as well as several unmapped genes and randomly sequenced cDNAs. Among the more interesting sequence similarities are those that represent novel human genes that are related to others with known or putative functions, such as one exon from a gene that may represent the human homolog of Drosophila Polycomb. It is anticipated that sequences from at least half of the genes residing on chromosome 22 are contained within this exon library. This approach is expected to facilitate fine-structure physical and transcription mapping of human chromosomes, and accelerate the process of disease gene identification.