An adult with progressive night blindness (retinitis pigmentosa) develops peripheral neuropathy, ataxia, and anosmia. Phytanic acid is elevated.
AR; PHYH (phytanoyl-CoA hydroxylase) or PEX7
- Phytanic acid accumulation
- Retinitis pigmentosa
- Peripheral neuropathy
- Cerebellar ataxia
- Anosmia
- Cardiac arrhythmias
- Markedly elevated plasma phytanic acid with normal or near-normal very-long-chain fatty acids (isolated alpha-oxidation defect)
- Pristanic acid is normal or low (helps distinguish from generalized peroxisomal disorders); not on newborn screening
- Confirm with PHYH (or PEX7) molecular testing or enzyme assay
- Dietary restriction of phytanic acid (dairy, ruminant fat)
reFSum, all Five Senses are out: hearing (deafness), vision (retinitis pigmentosa, cataracts, night blindness), touch (polyneuropathy), smell (anosmia), and taste are all affected.
"Referee for the Phyt": Refsum has isolated elevation in phytanic acid (alpha-oxidation defect). The fourth metatarsal is short in Refsum.
RReEEfsSSum: aRrhythmias, Retinitis pigmentosa, Ear issue (deafness), Epiphyseal dysplasia, Smell issue (anosmia), Scaly skin, ataxia.
Every "Phyt" (fight) needs a "Ref": Refsum disease is due to defective phytanyl-CoA hydroxylase, which is responsible for alpha-oxidation of phytanic acid.
