In summary, our study presents the identification of a de novo RARB c.157+1895G>A variant in an individual with a complex microphthalmia and provides functional data supporting the possible effect of this variant on RARB regulation (overexpression), which in turn likely promotes elevated FOXC1 expression, and increased cell proliferation in RARB-expressing cells during development. The gene discussed is FOXC1; the disease is microphthalmia.