High quality copy number and genotype data from FFPE samples using Molecular Inversion Probe (MIP) microarrays

BACKGROUND:A major challenge facing DNA copy number (CN) studies of tumors is that most banked samples with extensive clinical follow-up information are Formalin-Fixed Paraffin Embedded (FFPE). DNA from FFPE samples generally underperforms or suffers high failure rates compared to fresh frozen samples because of DNA degradation and cross-linking during FFPE fixation and processing. As FFPE protocols may vary widely between labs and samples may be stored for decades at room temperature, an ideal FFPE CN technology should work on diverse sample sets. Molecular Inversion Probe (MIP) technology has been applied successfully to obtain high quality CN and genotype data from cell line and frozen tumor DNA. Since the MIP probes require only a small (~40 bp) target binding site, we reasoned they may be well suited to assess degraded FFPE DNA. We assessed CN with a MIP panel of 50,000 markers in 93 FFPE tumor samples from 7 diverse collections. For 38 FFPE samples from three collections we were also able to asses CN in matched fresh frozen tumor tissue.RESULTS:Using an input of 37 ng genomic DNA, we generated high quality CN data with MIP technology in 88% of FFPE samples from seven diverse collections. When matched fresh frozen tissue was available, the performance of FFPE DNA was comparable to that of DNA obtained from matched frozen tumor (genotype concordance averaged 99.9%), with only a modest loss in performance in FFPE.CONCLUSION:MIP technology can be used to generate high quality CN and genotype data in FFPE as well as fresh frozen samples.This item is part of the UA Faculty Publications collection. For more information this item or other items in the UA Campus Repository, contact the University of Arizona Libraries at [email protected]

A systematic review of the diagnostic accuracy of physical examination for the detection of cirrhosis

BACKGROUND: We conducted a review of the diagnostic accuracy of clinical examination for the diagnosis of cirrhosis. The objectives were: to identify studies assessing the accuracy of clinical examination in the detection of cirrhosis; to summarize the diagnostic accuracy of reported physical examination findings; and to define the effects of study characteristics on estimates of diagnostic accuracy. METHODS: Studies were identified through electronic literature search of MEDLINE (1966 to 2000), search of bibliographic references, and contact with authors. Studies that evaluated indicants from physical examination of patients with known or suspected liver disease undergoing liver biopsy were included. Qualitative data on study characteristics were extracted. Two-by-two tables of presence or absence of physical findings for patients with and without cirrhosis were created from study data. Data for physical findings reported in each study were combined using Summary Receiver Operating Characteristic (SROC) curves or random effects modeling, as appropriate. RESULTS: Twelve studies met inclusion criteria, including a total of 1895 patients, ranging in age from 3 to 90 years. Most studies were conducted in referral populations with elevated aminotransferase levels. Ten physical signs were reported in three or more studies and ten signs in only a single study. Signs for which there was more study data were associated with high specificity (range 75–98%), but low sensitivity (range 15–68%) for histologically-proven cirrhosis. CONCLUSIONS: Physical findings are generally of low sensitivity for the diagnosis of cirrhosis, and signs with higher specificity represent decompensated disease. Most studies have been undertaken in highly selected populations