Gina Kolata writes an interesting story about the genetics of a pituitary giant ("New Story Writ by a Giant's DNA"). The individual in question is a man known as the "Irish Giant" who lived in 18th century England. His skeleton was preserved as a curiosity and remains in the collection of the Hunterian Museum.
[Korbonits] enlisted the help of an expert on ancient DNA, Joachim Burger of Gutenberg University in Mainz, Germany, to extract DNA from the giant’s teeth. She was worried that the DNA might be too degraded to analyze — after all, the giant’s corpse had been boiled in acid and then displayed in a museum for a couple of centuries.
It turns out to be a relatively low-penetrance Mendelian pituitary tumor, caused by a mutation shared by a few hundred living Irish people. It may occur elsewhere, and it would be interesting to figure out what elements of the genetic background may affect the trait's incidence.