** Shares of Applied Therapeutics APLT.O fall 80.3% to $1.70 after the bell
** Company says the U.S. FDA declined to approve its drug to treat galactosemia, a rare genetic metabolic disease
** The FDA's letter to the company said the marketing application for the drug, govorestat, cannot be approved in its current form, due to certain deficiencies - APLT
** Galactosemia can cause neurological complications, including deficiencies in speech, cognition, behavior and motor skills
** Up to last close, stock up more than double YTD
(Reporting by Christy Santhosh)
((Christy.Santhosh@thomsonreuters.com))