Variants in mitochondrial tRNA gene may not be associated with thyroid carcinoma

Detection of mitochondrial transfer RNA (mt-tRNA) gene mutations in patients with idiopathic pulmonary fibrosis and sarcoidosis

Mitochondrial reactive oxygen species production may lead to tissue injury associated with two respiratory disorders of unknown origin which are shared by common tissue fibrosis, IPF and sarcoidosis. Sequence analysis of 22 mt-tRNA genes and parts of their flanking genes revealed 32 and 45 mutations in 38/40 IPF and 69/85 sarcoidosis patients respectively. 4 novel mutations were identified. 15/32 and 25/45 mutations were exclusively expressed while 12/32 and 17/45 mutations predominantly occurred in IPF and sarcoidosis group respectively, compared to healthy controls. Novel mutation combinations were solely expressed in disease. Hence, a mitochondrial-mediated pathogenic pathway seems to underlie both entities.

Mutational analysis of mitochondrial tRNA genes in patients with lung cancer

Mutations in mitochondrial tRNA (mt-tRNA) genes have been found to be associated with various diseases including lung cancer. To understand the possible relationship between mtRNA mutations and lung cancer, we sequenced the 22 mt-tRNA genes from 200 lung cancer blood samples, as well as 100 healthy subjects. As a result, five mutations were identified including the tRNA^Ala T5655C, tRNA^Arg T10454C, tRNA^Leu(CUN) A12330G, tRNA^Ser(UCN) T7505C and tRNA^Thr G15927A. These mutations were absent in the healthy subjects. These mutations and polymorphisms were localized at the highly conserved nucleotides of the corresponding mitochondrial tRNAs, which are critical for the tRNA steady state level and may result in failure in the tRNA metabolism. Moreover, through the application of the pathogenicity scoring system, we found that only the T10454C mutation should be classified as a “neutral polymorphism,” while the other mutations were regarded as “definitely pathogenic.” Taken together, our data indicate that tRNA genes are the hot-spots for pathogenic mutations associated with lung cancer. Our findings may provide valuable information for pathophysiology, management and genetic counseling of lung cancer.