The word homozygosities is playable in Words With Friends™, no blanks required. Because it is longer than 7 letters, you would have to play off an existing word or do it in several moves.
Words With Friends™ Letter Score: 32
Highest Scoring Words With Friends™ Plays In The Letters homozygosities
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Seven Letter Word Alert: (36 words)
egoisms, egoists, egotism, gooiest, goosies, goosish, gothism, hogties, homiest, iotizes, isohyet, isozyme, meiosis, mitoses, mitosis, ooziest, shmoose, shmooze, smooths, smoothy, somites, soothes, stimies, stogeys, stogies, stomies, stooges, stymies, theisms, zoisite, zootomy, zygoses, zygosis, zygotes, zymoses, zymosis