Links
[1] http://ghr.nlm.nih.gov/gene/TK2
[2] https://disorders.eyes.arizona.edu/disorders/external-ophthalmoplegia-progressive-mtdna-deletions-ar-4
[3] http://omim.org/entry/617070
[4] http://ghr.nlm.nih.gov/gene/DGUOK
[5] https://disorders.eyes.arizona.edu/references/thymidine-kinase-2-mutations-autosomal-recessive-progressive-external-ophthalmoplegia