Marcus Gunn syndrome (Marcus Gunn phenomenon): a rare, congenital (present from birth) condition in which the upper eyelid moves (appears to wink) when the jaw moves. The condition may be accompanied by vision problems or other eye abnormalities (such as crossed eyes) and usually affects one eye though in rare cases may affect both eyes.

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References
Marcus Gunn phenomenon. Genetic and Rare Diseases Information Center (GARD). Updated: Mar 04, 2016.
<https://rarediseases.info.nih.gov/diseases/6972/marcus-gunn-phenomenon>
<https://rarediseases.info.nih.gov/diseases/6972/marcus-gunn-phenomenon>