Microsatellite analysis. Applications and pitfalls

Allelotyping in B-Cell Chronic Lymphocytic Leukemia (B-CLL)

B-cell chronic lymphocytic leukemia (B-CLL) is a heterogeneous malignant disease, both in terms of molecular abnormalities and clinical course. The most frequent chromosomal aberrations in B-CLL are deletions on 13q, 11q, and 17p, and trisomy 12, all of which are of prognostic significance. These aberrations can be detected by conventional cytogenetic analysis and fluorescence in situ hybridization (FISH), but cytogenetics are hampered by the low mitotic index of B-CLL cells, and FISH depends on genetic information of candidate regions. Microsatellites are unique highly polymorphic and informative genetic markers dispersed in the human genome. They have become the most commonly used markers to trace loss of heterozygosity in tumors. Their detection by PCR is rapid and can be semi-automated with maximal robustness and reproducibility. In this review, we discuss the implications of a recent genome-wide analysis in B-CLL with 400 microsatellite markers. This analysis led to the detection of new aberrant loci in B-CLL which are not visible in the leukemic conventional karyotype. We conclude that microsatellite allelotyping provides a complementary comprehensive view of genetic alterations in B-CLL, and it may identify new loci with candidate genes relevant in the molecular biology of B-CLL.

Advances in the clinical laboratory assessment of urinary sediment

Urinalysis has been used extensively in clinical practice to aid in the diagnosis of various renal and urologic diseases. The innovation of urinalysis is marching on right along with the rapid developments in biotechnology and astride from the solo urine cytology to sophisticated studies of individual component in the urinary sediment. In this review article, we focus on the use of flow cytometry and other technical advances in the examination of urinary sediment, the detection of urologic malignancies by the presence of microsatellite alteration in the urinary sediment, as well as the quantification of cytokine messenger RNA (mRNA) expression in urinary sediment by reverse transcription and real-time quantitative polymerase chain reaction (RT-QPCR). Notably, the study of cytokine mRNA expression in urinary sediment by RT-QPCR has recently been reported to provide important diagnostic information in kidney allograft recipients and patients with lupus nephritis. This simple and non-invasive method requires further study to determine its role in risk stratification and monitoring of therapeutic response in patients with other kidney diseases.

Circulating DNA: a new diagnostic gold mine?

The recent discovery that cell-free DNA can be shed into the bloodstream as a result of tumour cell death has generated great interest. Numerous studies have demonstrated tumour-specific alterations in DNA recovered from plasma or serum of patients with various malignancies, a finding that has potential for molecular diagnosis and prognosis. The implication is that tumour-derived nucleic acids of human or viral origin can be retrieved from blood by a minimally invasive procedure, and used as a surrogate tumour marker to monitor the course of the disease or aid in early diagnosis. The present review will describe the main areas of ongoing investigation, with particular emphasis on technical issues and available data of clinical relevance.