Additional findings_Adult
Gene: PHYH
MODERATE actionability by ClinGen.
Adult forms described. RD is clinically characterized by anosmia (absence of smell) and early-onset retinitis pigmentosa (RP), which are both universal findings with variable combinations of peripheral neuropathy, cerebellar ataxia, deafness, ichthyosis, and short metatarsals and metacarpals.
Treatment for many manifestations of RD are supportive: hydrating creams for ichthyosis, drugs for cardiac arrhythmias and cardiomyopathy, cataract surgery, and implantation of cochlear implants.
The standard therapy for prevention of primary manifestations is to lower plasma phytanic acid (PA) levels by dietary restriction of PA. For acute care or when diet is not sufficient, PA may be eliminated by plasmapheresis or lipid apheresis. These therapies have been found to reduce plasma PA concentrations by 50-70%, and possibly stabilize or improve symptoms of ichthyosis, sensory neuropathy, ataxia, improve cardiac arrhythmia, and extreme weakness. It is uncertain whether either treatment affects the progression of the anosmia, deafness, or RP and other ocular outcomes.
Sources: Expert listCreated: 22 Apr 2025, 10:06 a.m.
Mode of inheritance
BIALLELIC, autosomal or pseudoautosomal
Phenotypes
Refsum disease, MIM# 266500
Gene: phyh has been classified as Green List (High Evidence).
Gene: phyh has been classified as Green List (High Evidence).
gene: PHYH was added gene: PHYH was added to Additional findings_Adult. Sources: Expert list Mode of inheritance for gene: PHYH was set to BIALLELIC, autosomal or pseudoautosomal Phenotypes for gene: PHYH were set to Refsum disease, MIM# 266500 Review for gene: PHYH was set to GREEN