Eli Lilly & Co. said it will buy Prevail Therapeutics Inc. for about $1 billion to gain gene therapies that treat neurodegenerative disease such as Parkinson’s.

Lilly will pay $22.50 per share in cash payable at closing plus one non-tradeable contingent value right worth up to $4 per share for a total of as much as $26.50 per share, according to a statement. The contingent value right is payable upon the first regulatory approval of a product from Prevail.

Prevail’s gene therapy program, aimed at conditions like Parkinson’s disease and certain forms of dementia, will create a new avenue for drug discovery and development at Lilly. The move follows a trend toward rare-disease treatments at big drugmakers, one that AstraZeneca Plc jumped into recently with its $39 billion deal for Alexion Pharmaceuticals Inc.

Lilly also updated its financial guidance, citing strong demand for key medicines. It said it now expects sales of $24.2 billion to $24.7 billion this year, up from a previous range that was $500 million lower. Earnings per share are expected to be $6.28 to $6.48, up 8 cents a share from the previous range. The company said it expects earnings of $7.25 to $7.90 a share for 2021.