Alternative titles; symbols
HGNC Approved Gene Symbol: MT-TQ
SNOMEDCT: 129565002, 39925003; ICD10CM: E88.41, G72.9, M60-M63, M62.9; ICD9CM: 359.9;
The mitochondrial tRNA for glutamine is encoded by nucleotides 4329-4400.
Dey et al. (2000) reported a novel mitochondrial DNA alteration in a 12-year-old boy with myopathy. They demonstrated a single nucleotide insertion (an adenine) in a polyadenine stretch at mitochondrial DNA positions 4366-4369 in the MTTQ gene. This altered the length of the evolutionarily conserved anticodon loop from 7 to 8 bases. The insertion was heteroplasmic and was abundant in the patient's muscle. Lower proportions of mutated mitochondrial DNA were observed in skin fibroblasts, but were below detectable levels in white blood cells. A muscle biopsy of the patient showed ragged-red fibers and an unusually high percentage of cytochrome c oxidase-deficient fibers (89%). The pathogenicity of the mutation was also evidenced by the fact that fibers harboring lower levels of the mutation showed normal cytochrome c oxidase activity.
Finnila et al. (2001) analyzed 1 group including 480 controls and 575 patients with diseases manifesting in middle life, including diabetes, epilepsy, sensorineural hearing loss, occipital stroke, and migraine, and a second group including 497 patients with Alzheimer disease, non-Alzheimer dementia, or Parkinson disease. The 4336A-G transition was found in 8 patients and 3 controls in group 1, this being most frequent among patients with sensorineural hearing impairment and migraine. Five patients in group 2, but none of the controls, also had the 4336A-G transition.
Bataillard et al. (2001) reported an atypical case of MELAS syndrome (540000) associated with a 4332G-A mutation in the MTTQ gene. The patient was a 47-year-old male with sensorineural deafness since age 20 years, who presented with an acute stroke in the absence of cardiovascular disease. Although late onset and some neuroradiographic findings were atypical for MELAS, there were extensive basal ganglia calcifications and muscle COX activity was decreased with severely deficient fibers. The 4332G-A mutation was present in 81% of the patient's mtDNA muscle molecules, and absent from his mtDNA blood and skin cells. The mutation was not found in mtDNA blood cells from his mother and brother or in 300 controls. The authors emphasized the genetic heterogeneity of the MELAS syndrome.
Bataillard, M., Chatzoglou, E., Rumbach, L., Sternberg, D., Tournade, A., Laforet, P., Jardel, C., Maisonobe, T., Lombes, A. Atypical MELAS syndrome associated with a new mitochondrial tRNA glutamine point mutation. Neurology 56: 405-407, 2001. [PubMed: 11171912] [Full Text: https://doi.org/10.1212/wnl.56.3.405]
Dey, R., Tengan, C. H., Morita, M. P. A., Kiyomoto, B. H., Moraes, C. T. A novel myopathy-associated mitochondrial DNA mutation altering the conserved size of the tRNA(gln) anticodon loop. Neuromusc. Disord. 10: 488-492, 2000. [PubMed: 10996779] [Full Text: https://doi.org/10.1016/s0960-8966(00)00125-5]
Finnila, S., Autere, J., Lehtovirta, M., Hartikainen, P., Mannermaa, A., Soininen, H., Majamaa, K. Increased risk of sensorineural hearing loss and migraine in patients with a rare mitochondrial DNA variant 4336A-G in tRNA(gln). (Letter) J. Med. Genet. 38: 400-405, 2001. [PubMed: 11424923] [Full Text: https://doi.org/10.1136/jmg.38.6.400]