Refsum syndrome Flashcards
(26 cards)
What is the inheritance pattern of Refusm syndrome?
Autosomal recessive
Which genes are associated with Refusm syndrome?
PAHX gene on 10p, PEX7 gene on 6q
What prenatal diagnostic methods can be used for Refusm syndrome?
CVS/amniocentesis: phytanic acid oxidase assay on cultured cells; DNA analysis
What is the incidence of Refusm syndrome?
Rare; approximately 100 cases reported
At what age do neurologic symptoms of Refusm syndrome typically start?
In childhood
When do cutaneous changes usually occur in Refusm syndrome?
Usually as an adult
What causes the deficiency in Refusm syndrome?
Mutations in the PAHX gene create a deficiency in phytanoyl-CoA hydroxylase
What is the role of phytanoyl-CoA hydroxylase?
It is a peroxisomal enzyme responsible for the catalyzation of phytanic acid
What happens due to the deficiency of phytanoyl-CoA hydroxylase?
Accumulation of phytanic acid in serum and replacement of normal fatty acids in the epidermial lipids and other tissues throughout the body
What other gene mutation can cause Refusm syndrome?
Mutations in the PEX7 gene that encodes peroxin 7
What are the key skin features of Refusm syndrome?
Mild ichthyosis (i.e., ichthyosis vulgaris) usually beginning after neurologic symptoms
What central nervous system symptoms are associated with Refusm syndrome?
Cerebellar ataxia, progressive peripheral polyneuropathy
What ocular symptom is present in Refusm syndrome?
Retinitis pigmentosa with salt and pepper pigment, secondary night blindness
What ear-nose-throat symptom is associated with Refusm syndrome?
Sensorineural deafness
What cardiac issues are related to Refusm syndrome?
Arrhythmias with heart block, cardiac failure
What musculoskeletal features are seen in Refusm syndrome?
Symmetric muscular wasting, variety of skeletal anomalies
What are some differential diagnoses for Refusm syndrome?
- Peroxisomal deficiency disorders
- Ichthyosis vulgaris
- Vitamin B deficiency
What laboratory findings are indicative of Refusm syndrome?
Increased serum phytanic acid; decreased phytanic acid oxidase activity in cultured fibroblasts
What does a skin biopsy reveal in Refusm syndrome?
Lipid-filled vacuoles in basal keratinocytes
What is a characteristic finding in cerebrospinal fluid (CSF) in Refusm syndrome?
Increased cerebrospinal fluid (CSF) protein without cells
What dietary management is recommended for patients with Refusm syndrome?
Dietary restriction of phytanic acid: decrease green vegetables, dairy products, and ruminant fats
What treatment can assist in the removal of phytanic acid?
Plasma exchange removal of phytanic acid
Which specialists should Refusm syndrome patients be referred to?
- Neurologist
- Ophthalmologist
- Cardiologist
- Dermatologist
- Otolaryngologist
- Physiatrist
What is the prognosis if diet and exchange are instituted early in Refusm syndrome?
Progression of disease can be halted
