xAI cofounder is taking a step back to 'go founder mode on my health' after Lyme disease diagnosis

In a significant personal development, an xAI co-founder has announced a temporary withdrawal from his role at the company due to a recent Lyme disease diagnosis. Greg Yang shared his decision in a post on X, revealing that he will transition to an informal advisory capacity at Elon Musk's venture, allowing him to prioritize his health. Yang's journey with Lyme disease began following a period of unexplained fatigue that arose after an illness in early 2025. Initially believing he had recuperated, he soon faced persistent tiredness and a notable decline in his energy and creativity. As time progressed, he experienced worsening symptoms, with even minor physical activities or specific foods leaving him drained for days. The co-founder recounted a particularly alarming week where he found himself sleeping up to 12 hours daily yet still felt exhausted. After undergoing several medical evaluations, Yang received the Lyme disease diagnosis, a condition often challenging to identify. He expressed surprise at this revelation, as he had no recollection of being bitten by a tick, suggesting that he may have contracted the illness long before it manifested. Yang mentioned that the pressures of building xAI likely compromised his immune system, making the symptoms more apparent. However, he remains optimistic, feeling fortunate to have identified the condition early enough to address it effectively. "This will allow me to recover and return stronger than ever," he stated. Elon Musk responded to Yang’s announcement with well-wishes, expressing hope for his swift recovery and humorously suggesting that the company’s AI, Grok, might assist in finding a cure. Yang, who joined xAI as a co-founder in June 2023 after nearly six years at Microsoft, is the latest in a line of co-founders to step back from the company, following the departures of Igor Babuschkin and Christian Szegedy in the previous year.