Abstract
Purpose :
SPG56 is an autosomal recessive form of hereditary spastic paraplegia (HSP) due to mutations in CYP2U1. The gene is involved in lipid metabolism and is implicated in mitochondrial disorders.
Here we describe the retinal phenotype/genotype correlation of novel CYP2U1 mutations, in a neurologically asymptomatic patient, whose brother was diagnosed with HSP56
Methods :
3 brothers from a Swiss, non-consanguineous family, were examined following the diagnosis of Strümpell-Lorrain disease (Hereditary Spastic Paraplegia 56) in the oldest child, when he was 2 years old. The youngest brother only complained of visual problems and was referred for reduced visual acuity at age 15 years. Since then he had a follow up of 4 years. Both brothers had full ophthalmological evaluation including fundus color photography, optical coherence tomography (OCT), fundus autofluorescence (fAF) and angio OCT, molecular diagnosis, full field ERG’s and EOG
Results :
Next generation sequencing revealed a novel c[452C>T],p [Pro151Leu];c.[943C>T], p.[GLN315*] mutations in CYP2U1 gene in both brothers. The youngest, neurologically asymptomatic, had a BCVA of 0.8 in both eyes. The VA decreased to 0.6 bilaterally 4 years later. The patient also complained of photophobia. OCT showed disorganised parafoveal inner retina (hyperreflective INL), with focal atrophies, which increased over time. Some cysts also appeared at the junction of ONL and OPL at the fovea. The full field ERGs, EOG and VF were both within normal limits. Angio OCT was within normal limits. AF images showed patchy hyperafluorescent areas at the macula, which increased over the 4 years old period. The brother with HSP56 had similar finding, his visual acuity was 0.8 bilaterally, OCT and AF had similar appearance, but in a milder form.
Conclusions :
Progressive macular dystrophy due to changes in the inner and outer retina can be the first and only manifestation of mutations in CYP2U1, known as causative of HSP56. CYP2U1 should be included in panels of genes involved in Macular dystrophies
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.