Loss of heterozygosity (LOH)--implications for human genetic identification

The aim of this study was assessment of possible effects of loss of heterozygosity on human genetic identification of histolopathogical tissue sections. DNA templates were extracted from tumour tissue specimens excised from oncological patients and from reference blood samples. AmpFlSTR Identifiler PCR Amplification Kit and ABI 310 Genetic Analyzer (Applera) were used to obtain genetic profiles. Frequency of LOH was calculated for respective samples. Fisher's exact test was performed for statistical analysis. Forty-two percent of the 101 cancer cases analysed were found to possess alterations of the microsatellites manifesting with allelic loss. The most frequently altered loci were D3S1358 and D18S51. The alteration was detected in 47% of cases with larynx carcinoma, 44% of cases with uveal melanoma, 60% of cases with cervical cancers, one case of liposarcoma G3 and one case od neurofibrosarcoma. No LOH was found in liposarcoma G1, dermatofibrosarcoma and cystosarcoma protuberans in either primary or recurrent tumours. In benign tumours (lipoma and fibroma) LOH was also absent. During genotyping of DNA extracted from histopathological tissue sections caution should be taken when non-match or exclusion based on few discrepancies is concluded.