A Validation Study of Vascular Cognitive Impairment Genetics Meta-Analysis Findings in an Independent Collaborative Cohort

Vascular cognitive impairment (VCI), including its severe form, vascular dementia (VaD), is the second most common form of dementia. The genetic etiology of sporadic VCI remains largely unknown. We previously conducted a systematic review and meta-analysis of all published genetic association studies of sporadic VCI prior to 6 July 2012, which demonstrated that APOE (ɛ4, ɛ2) and MTHFR (rs1801133) variants were associated with susceptibility for VCI. De novo genotyping was conducted in a new independent relatively large collaborative European cohort of VaD (nmax = 549) and elderly non-demented samples (nmax = 552). Where available, genotype data derived from Illumina's 610-quad array for 1210 GERAD1 control samples were also included in analyses of genes examined. Associations were tested using the Cochran-Armitage trend test: MTHFR rs1801133 (OR = 1.36, 95% CI 1.16-1.58, p = <0.0001), APOE rs7412 (OR = 0.62, 95% CI 0.42-0.90, p = 0.01), and APOE rs429358 (OR = 1.59, 95% CI 1.17-2.16, p = 0.003). Association was also observed with APOE epsilon alleles; ɛ4 (OR = 1.85, 95% CI 1.35-2.52, p = <0.0001) and ɛ2 (OR = 0.67, 95% CI 0.46-0.98, p = 0.03). Logistic Regression and Bonferroni correction in a subgroup of the cohort adjusted for gender, age, and population maintained the association of APOE rs429358 and ɛ4 allele.

A Validation Study for the Use of ROS1 Immunohistochemical Staining in Screening for ROS1 Translocations in Lung Cancer

INTRODUCTION: The presence of ROS proto-oncogene 1, receptor tyrosine kinase gene (ROS1) rearrangements in lung cancers confers sensitivity to ROS kinase inhibitors, including crizotinib. However, they are rare abnormalities (in ∼1% of non-small cell lung carcinomas) that are typically identified by fluorescence in situ hybridization (FISH), and so screening using immunohistochemical (IHC) staining would be both cost- and time-efficient.

METHODS: A cohort of lung tumors negative for other common mutations related to targeted therapies were screened to assess the sensitivity and specificity of IHC staining in detecting ROS1 gene rearrangements, enriched by four other cases first identified by FISH. A review of published data was also undertaken.

RESULTS: IHC staining was 100% sensitive (95% confidence interval: 48-100) and 83% specific (95% confidence interval: 86-100) overall when an h-score higher than 100 was used. Patients with ROS1 gene rearrangements were younger and typically never-smokers, with the tumors all being adenocarcinomas with higher-grade architectural features and focal signet ring morphologic features (two of five). Four patients treated with crizotinib showed a partial response, with three also showing a partial response to pemetrexed. Three of four patients remain alive at 13, 27, and 31 months, respectively.

CONCLUSION: IHC staining can be used to screen for ROS1 gene rearrangements, with patients herein showing a response to crizotinib. Patients with tumors that test positive according to IHC staining but negative according to FISH were also identified, which may have implications for treatment selection.

Validation of immunocytochemistry as a morphomolecular technique

Immunocytochemistry (ICC) is a long-established means for clinical laboratories to investigate material for which it is difficult to obtain tissue samples. Unlike immunohistochemistry (IHC), the cells do not retain surrounding tissue environment/architecture. This can be of benefit in that fixation is often immediate and rapid, protecting the cells. Although fixation is frequently observed as the main preanalytic variable of test quality, all cytology preanalytic factors should be identified and controlled. In addition, the validation of ICC should take the same rigorous approach that other molecular pathology techniques follow. A three-step validation protocol is offered here. The end result is a comprehensive, morphomolecular approach to ICC, with an emphasis on therapeutic ICC.