Refsum disease due to the splice-site mutation c.135-2A>G before exon 3 of the PHYH gene, diagnosed eight years after detection of retinitis pigmentosa

Abstract

Objectives If Refsum disease (RD) is not considered as a differential at onset of the initial manifestations the diagnosis of RD remains unrecognized for a long time as in the following case. Case report A 55-y old Caucasian female with hyperextensible joints developed progressive visual impairment due to retinitis pigmentosa and sensorimotor polyneuropathy of the lower limbs since age 32 y. Screening for causes of polyneuropathy at age 40 y revealed markedly elevated serum phytanic acid (PA) with a maximum value of 293.6 μg/ml ( n:< 6 μg/ml) why RD was diagnosed. Since age 48 y slowly progressive hypacusis was noted. RD was caused by the known transition A135G in exon 3 of the PHYH gene. Additionally, the polymorphism T153C in exon 3 of the PHYH gene was detected. Upon strict adherence to the Chelsea diet PA levels slightly decreased since onset of this therapy. Conclusion This case confirms that RD remains unrecognized for a long time if RD is not considered as a differential of retinitis pigmentosa as the initial manifestation of the disease. Early recognition of RD is important since there is the therapeutic option of starting a diet.