A 12-year-old girl presents with optic atrophy, pale papilla, amblyopia and microcephaly (-3 s.d.) with mild mental retardation and facial dysmorphism. She had mitral insufficiency with mitral prolapse and moderate short stature (-2.5 d.s.). She had normal flash visual evoked potentials, normal electroretinograms and electrooculograms and normal cranial CT scan as well as other lab tests to rule out malformations, tumors or multiple sclerosis. Her lymphocyte karyotype showed a variegated mosaicism with: 2 cells with 49, XX, +mar,+mar,+mar; 21 cells with 48, XX, +mar,+mar; 57 cells, with 47, XX,+mar; 20 cells with 46,XX; while parental karyotypes were normal. This syndrome therefore associates optic atrophy, mental retardation and microcephaly and short stature with chromosomal instability in the form of variegated mosaicism.