Figure 1. Family trees of the patients with the m.15992A>T mutation.

Arrows indicate the proband in each family; stars = subjects with samples for molecular studies; white forms = subjects asymptomatic or without sufficient information; black forms = patients with severe exercise intolerance, i.e., disabling daily life; gray forms = moderate exercise intolerance, i.e., not disabling daily life but clearly experienced; stripped forms = patients with isolated chewing-induced masseter swelling; question marks indicate unknown clinical status of the subject. In families 1 and 5, severe intolerance to exercise was constantly associated with chewing-induced masseters swelling, but the reverse was not true with several patients in family 5 presenting only chewing-induced masseters swelling.