This is a Phase 2a study of the effect of serine supplementation and fenofibrate treatment on serum deoxysphingolipid levels in patients with macular telangiectasia type 2 (MacTel). This study involves six arms. Participants will be randomly assigned to one of the following treatment groups: serine 200 mg/kg/day, serine 400 mg/kg/day, fenofibrate 160 mg/day, both serine 200 mg/kg/day and fenofibrate 160 mg/day, both serine 400 mg/kg/day and fenofibrate 160 mg/day, or no treatment (control group). Serum deoxysphingolipid levels will be used as the primary outcome, and safety will be evaluated. The participants will be followed for 10 weeks, with visits at Screening, Week 0, 3, 6 and 10.

Additional Procedures include:

1. Fasting blood work
2. Collection of microbiome samples

Inclusion Criteria:

1. Signed and dated written informed consent obtained from the participant in accordance with the local regulations;
2. Males/females 21 years of age or older;
3. English speaking;
4. Enrolled in the Natural History Observation and Registry Study (NHOR) and diagnosed with confirmed MacTel type 2 in at least one eye;
5. Willing to use contraception, if applicable; and
6. Willing to comply with study protocol and follow-up visits.

Exclusion Criteria:

1. Participant is unable to provide informed consent;
2. Participant is less than 21 years of age;
3. Participant is currently taking, or has taken within four weeks prior to screening, a serine or glycine supplement;
4. Participant is currently taking, or has taken within 12 months prior to screening, fibrates including clofibrate, ciprofibrate, bezafibrate, fenofibrate, and gemfibrozil;
5. Participant is currently taking an anticoagulant, colchicine, cyclosporine, tacrolimus or bile acid binding resins;
6. Participant has known allergy to fibrates and/or serine;
7. Participant has a known history of clinically significant myopathy or myalgia related to cholesterol-lowering drugs;
8. Participant has active liver disease and/or elevated liver enzymes*;
9. Participant has renal dysfunction as evidenced by elevated serum creatinine* and/ or glomerular filtration rate (GFR) less than 90 mL/min;
10. Participant has thrombocytopenia as evidenced by a platelet count below 100,000 per microliter, anemia as evidenced by hemoglobin levels below 10 g/dL, or history of bleeding disorder;
11. Participant has a history of gallbladder disease or has had a cholecystectomy;
12. Participant has triglyceride levels greater than 400 mg/dL on treatment, or greater than 700 mg/dL on no treatment;
13. Participant has untreated/uncured Hepatitis C, or a history of Hepatitis B, autoimmune hepatitis, or HIV;
14. Participant has had any malignancies within the last 5 years (not including basal cell carcinoma);
15. Participant has ever been enrolled in a clinical trial involving ciliary neurotrophic factor (CNTF) treatment;
16. Participant is currently enrolled in another clinical trial that involves treatment or participated in one within the last 30 days;
17. Participant is pregnant, breastfeeding or planning a pregnancy;
18. Participant is medically unable to comply with study procedures or follow-up visits;
19. Participant has, in the opinion of the Investigator, any physical or mental condition that would increase the patient's risk of participation in the study or may interfere with the study procedures, evaluations and outcome assessments; or
20. Patient is unavailable for follow-up visits. *based on reference range for the local laboratory used

This is an open-label study. Participants will be told if they are taking serine and/or fenofibrate, or if they are participating as a control (no treatment).