Which of the following is NOT a cause of loss of proprioception?

Loss of proprioception can occur due to various neurological and physiological conditions that affect the nerve pathways responsible for sensory feedback from the muscles and joints. In this context, conditions like diabetes, tertiary syphilis, and vitamin B12 deficiency are known to cause nerve damage or issues that can result in impaired proprioception.

Diabetes can lead to peripheral neuropathy, where nerve fibers are damaged due to prolonged high blood sugar levels, impacting one's ability to sense body position. Tertiary syphilis can affect the spinal cord, particularly the posterior columns, which are crucial for proprioceptive sensation. Vitamin B12 deficiency can also cause peripheral nervous system issues and subacute combined degeneration of the spinal cord, which can noticeably affect proprioception.

On the other hand, asthma is primarily a respiratory condition and does not directly affect the nervous system or the proprioceptive pathways. Therefore, it is not associated with the loss of proprioception like the other mentioned conditions. This makes asthma the correct answer as it does not contribute to the loss of proprioceptive function.