Treatment of Retinitis Pigmentosa in Refsum Syndrome with Elevated Phytanic Acid
Clinical Scenario
Retinitis pigmentosa presenting as a manifestation of Refsum syndrome — an autosomal recessive disorder of phytanic acid metabolism (also known as phytanic acid storage disease) — with an elevated serum phytanic acid level in the range of 10 to 30 mg/dL.
Key finding
Normal plasma phytanic acid is below 0.3 mg/dL and is generally undetectable on routine analysis. In Refsum syndrome, levels rise substantially, with phytanic acid comprising 5–30% of total plasma fatty acids. Diagnosis is established by detection of phytanic acid in the plasma.
Treatment Approach
Management centers on reducing systemic phytanic acid burden through targeted dietary modification — eliminating sources of phytanate and its precursors. Additional measures addressing stored phytanic acid may be incorporated depending on clinical circumstances.
Clinical Goal
The therapeutic target is reduction of plasma and tissue phytanic acid levels toward the normal range (below 0.3 mg/dL).
References
DOI: 10.1016/0039-6257(88)90085-9
- Refsum syndrome, an autosomal recessive disorder, was originally called heredopathia atactica polyneuritiformis, and more recently phytanic acid storage disease.
- Diagnosis is established by detection of phytanic acid in the plasma.
- Normal human plasma contains a trace of phytanic acid (less than 0.3 mg/dL) which is usually undetectable in routine analysis, whereas patients with Refsum syndrome have levels ranging from 10 to 30 mg/dL with 5 to 30% of the total fatty acids in plasma being phytanic acid.
- Treatment consists of elimination of dietary sources of phytanate and its precursors in order to reduce plasma and tissue levels of phytanic acid.
- Periodic plasmapheresis may be used as well to mobilize phytanic acid from body fat stores.
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