Aug 9 (Reuters) - Illumina Inc lowered annual profit forecast on Wednesday, signaling weak demand for its sequencing and diagnostic services, sending the life sciences firm's shares down 7.5% after the bell.

The San Diego, California-based company expects full-year adjusted profit per share to be between $0.75 and $0.90, compared with its prior forecast of $1.25 to $1.50 per share.

(Reporting by Pratik Jain in Bengaluru; Editing by Shilpi Majumdar)