What is MacTel?

MacTel (Macular Telangiectasia) is a degeneration of the center of the retina (called the macula) that affects central vision. The macula is a type of nerve tissue that works to give sharp central vision to read and see fine details. There is evidence that an amino acid called serine plays a role in the cause MacTel.¹

How does serine relate to MacTel?

Serine is an amino acid that is used by the body to build proteins and lipids. If this building block is not used properly by the body, abnormal nerve lipids (deoxysphingolipids) may accumulate and damage nerve cells.

 In an inherited condition (hereditary sensory and autonomic neuropathy type 1) an abnormal enzyme causes abnormal nerve lipids in the body and can cause nerve damage. Peripheral nerve damage may cause numbness and tingling of the hands and feet. Autonomic nerve damage may interfere with internal organ function (e.g. intestines, bladder, heart). In addition, these patients frequently develop MacTel.  

Even without this inherited condition of neuropathy, patients with MacTel often have low blood levels of serine that result in high blood levels of abnormal nerve lipids. These abnormal nerve lipids have been shown to damage retinal cells and likely play a role in loss of vision in MacTel.

 What can be done with this information?

At present (1-2020) the authors of the research paper advise against starting treatment based on their paper. They caution that more research is needed. However, the FDA found that over-the-counter L-serine supplements to be generally safe. One study found the use of L-serine (400mg/kg/day) safely lowered the abnormal nerve lipids in a case of hereditary sensory and autonomic neuropathy.² Side effects of taking L-serine include stomach discomfort, diarrhea, constipation, and frequent urination. Most supplements come in the form of capsules containing L-serine 500mg. It is unknown what dosage might be most effective for MacTel. A patient may wish to take the dosage recommended on the bottle by the manufacturers.

Check for current prices of L-serine on Amazon.

Another option is the use of fenofibrate, a prescription medication that can lower the abnormal nerve lipid levels. This option may be especially useful in patients with MacTel who have abnormal cholesterol and/or triglycerides because fenofibrate has already been approved for use in the treatment of these conditions apart from potential benefit for MacTel. 

In general, patients with MacTel who also have symptoms of sensory or autonomic neuropathy should notify their retinal specialist and internist for additional testing and consider treatment.

By Scott E. Pautler, MD

For a telemedicine consultation with Dr Pautler, please send email request to spautler@rvaf.com. We accept Medicare and most insurances in Florida. Please include contact information (including phone number) in the email. We are unable to provide consultation for those living outside the state of Florida with the exception of limited one-time consultations with residents of the following states: Alabama, Arkansas, Connecticut, Georgia, Minnesota, and Washington.

References:

1. Gantner, et al. Serine and lipid metabolism in macular disease and peripheral neuropathy. N Eng J Med 2019;10:1422-1433.

2. Auranen et al. Clinical and metabolic consequences of L-serine supplementation in hereditary sensory and autonomic neuropathy type 1C. Cold Spring Herb Case Stud 2017;3:6.

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