| Type | MGI:General | Description | in vitro, sternomastoid muscles from young (3- to 4-mo-old) homozygotes show no significant differences in isometric twitch or tetanic force, contraction or relaxation times relative to wild-type muscles in contrast, sternomastoid muscles from older (7- to 11-mo-old) homozygotes show a 30%-50% reduction in twitch and tetanic force generation relative to wild-type muscles |
