We investigated the allele and genotype frequencies of two common CRTH2 single nucleotide polymorphisms (SNPs) [G1544C and A1651G (rs 545659)] in the 3'-untranslated region and the relationship between these SNPs and serum IL-13 levels in Chinese children patients with asthma. For G1544C and A1651G SNPs, there were significant differences in allele and genotype frequencies between asthma patients and controls. Haplotype analysis yielded additional evidence of linkage disequilibrium for the 1544G-1651G haplotype (P < 0.01). Moreover, serum IL-13 levels were significantly different among genotypes in G1544C, A1651G SNPs. These results suggest that SNPs of G1544C and A1651G might be act as susceptibility genetic factors of asthma.

ABSTRACT. Mitochondrial DNA mutations play crucial roles in the pathogenesis and progression of human malignancies. Therefore, to determine whether maternal background or mitochondrial DNA somatic mutations were essential cofactors in the lung cancer of Chinese patients as well, the complete mitochondrial DNA displacement loop of the primary cancerous, matched para-cancerous normal and distant normal tissues for 79 Chinese patients with lung cancer were analyzed in this study. Our results indicated that the higher detected frequency of haplogroups prevalent in southern East Asia (53.16%; 42/79) versus those of northern East Asia in the studied population supported the southern East Asian characteristics of the Chinese lung cancer group. Further statistical analysis revealed that the haplogroups F* and G* contributed to the susceptibility to lung cancer in Chinese patients. In addition, by comparing sequences from different tissues of the same patients, a total of eight somatic mutations from six patients were detected. Combined with the fourteen somatic mutations identified in our previous study, the somatic mutation spectrum of the 79 Chinese patients with lung cancer was 25.32% (20/79). Our results suggest that mitochondrial DNA haplogroups and somatic mutations are associated with lung cancer in patients from Yunnan, Southwest China, and that somatic mitochondrial DNA mutations in the displacement loop can serve as potential biomarkers for clinical utility.

To characterize the somatic mutation spectrum of mitochondrial DNA at D310 in Chinese lung cancer patients and evaluate its potential significance in Chinese lung cancer diagnosis, in this study, 237 samples, including lung tumor, adjacent normal tissue and blood samples of 79 lung cancer patients were analyzed. By comparing sequences of D310 between lung cancer tissues, adjacent normal tissue and blood samples, the somatic mutations at D310 were detected in 17.72% (14/79) of Chinese lung cancer patients; this implied that somatic mutations at D310 could be served as valuable biomarker for diagnostic of Chinese lung cancer. Further analyses indicated that deletion and heterogeneity were the predominant characters for somatic mutations detected at D310 of Chinese lung cancer patients.

ABSTRACT. Formalin fixation and paraffin embedding is widely used for convenient and long-term storage of tumor tissue and precious sources to perform genetic studies. However, DNA fragmentation is one of the major flaws of genomic DNA isolation from formalin fixation tissues, which limits its further usage. Here, we present an improved method for isolating high-quality genomic DNA from formalin fixation tissue. We obtained high-quality genomic DNA of more than 20 kb from samples frozen for more than 2 years. Furthermore, to verify DNA quality, the whole mitochondrial DNA (mtDNA) genomes from the normal and tumor tissue of the same patient were successfully amplified with two overlapping PCR fragments comprising more than 8379 bp in length for each fragment. In addition, the whole genomes were sequenced with a 48-well based primer panel in order to avoid potential sequencing errors from artificial recombination, which was further confirmed with an mtDNA phylogenetic strategy. Our improved DNA extraction method from formalin fixation tissue and sequencing strategy for entire mtDNA genomes will generate unambiguous sequence analysis results for clinical samples.

ABSTRACT. The mitochondrion is a crucial intracellular organelle responsible for regulating cellular energy metabolism, producing free radicals, initiating and executing the apoptotic pathways. Previous studies have shown that somatic mutations in mitochondrial DNA are associated with various tumors, which may be involved during carcinogenesis and tumor progression. To examine the mutation pattern in cancer, 625 reported somatic mutations in the mitochondrial DNA genome were analyzed. We found that, except for deletions and insertions, most somatic mutations were point mutations, accounting for 89.44% of somatic mutations. Transition was the predominant form of X.Z. Chen et al. 4332©FUNPEC-RP www.funpecrp.com.br Genetics and Molecular Research 14 (2): 4331-4337 (2015) somatic mutation in the entire mitochondrial DNA genome, accounting for 87.12% of point mutations, most of which were homoplastic. Frequency statistics analysis of point mutations indicated that, except for 3 tRNA genes, the mutations were distributed on all resting genes and in the D-loop region, with the latter showing the highest frequency of somatic mutation (19.34%), followed by the tRNA leucine 2 gene and non-coding regions between base pairs 5892 and 5903, while 13 coding-region genes and 2 rRNA genes showed a relatively lower frequency of somatic point mutations. Nonsynonymous mutations and terminal amino acid changes were the primary point somatic mutations detected from 13 coding-region genes, which may cause mitochondrial dysfunction in cancer cells. We found that the somatic mutations may affect the mitochondrial DNA genome; the non-coding region should be examined to identify somatic mutations as potential diagnostic biomarkers for early detection of cancer.