Mitochondrial encephalopathy with lactic acidosis and strokelike episodes–related syndrome
C. Genetic testing to rule out a mitochondrial disease
Macular atrophy may represent the clinical outcome of different disorders sharing some overlap in the biological pathways. While age-related macular degeneration is the most common disorder associated with macular atrophy, macular atrophy may be also the result of medications-associated retinal toxicity, ocular inflammation, and genetically determined retinal dystrophies. A detailed collection of medical and family history is mandatory as initial workup in cases of macular atrophy.
Mitochondrial encephalopathy with lactic acidosis and strokelike episodes syndrome (MELAS) represents a clinical entity associated with mitochondrial dysfunction.1,2 As with other mitochondrial disorders, MELAS is maternally inherited and is characterized by incomplete penetrance.1- 3 MELAS is due to mitochondrial DNA (mtDNA) mutations. Specifically, the MT-TL1 mitochondrial gene (OMIM 590050) is the most frequently mutated and, in particular, the most frequent is the point mutation m.3243A>G/MT-TL1.4,5 Besides the full-blown MELAS,1,2 this disorder may have variable clinical expressivity with a broad spectrum of manifestations.4,5 This variability is partially related to the phenomenon of heteroplasmy, defined as the coexistence of wild-type and mutated mtDNA copies in the same cell. As distinct cells and tissues may have different heteroplasmy percentages, the phenotypic expression may vary among patients.6- 10