EFEMP1 rare variants cause juvenile-onset open angle glaucoma in
families from the Philippines
Abstract
Juvenile open angle glaucoma (JOAG) is a severe type of glaucoma with
childhood onset and dominant inheritance. Using exome sequencing we
identified 3 independent families from the Philippines with rare EFEMP1
variants (c.238A>T, p.Asn80Tyr; c.1480T>C
p.Ter494Glnext*29; and c.1429C>T, p.Arg477Cysteine )
co-segregating with disease. Affected variant carriers (N= 34) exhibited
severe disease with average age of onset of 16 years and with 76%
developing blindness. To investigate functional effects, we transfected
COS7 cells with vectors expressing the three novel EFEMP1 variants and
showed that all three variants found in JOAG patients caused significant
intracellular protein aggregation and retention compared to wild type
and also compared to EFEMP1 variants associated with other ocular
phenotypes including an early-onset form of macular degeneration,
Malattia Leventinese/Doyne’s Honeycomb retinal dystrophy. These results
suggest that rare EFEMP1 coding variants can cause JOAG through a
mechanism involving protein aggregation and retention, and that the
extent of intracellular retention correlates with disease phenotype.
This is the first report of EFEMP1 variants causing JOAG, expanding the
EFEMP1 disease spectrum. Our results suggest that EFEMP1 mutations
appear to be a relatively common cause of JOAG in Filipino families, an
ethnically diverse population.