Clinical and molecular findings in eight Egyptian patients with suspected mitochondrial disorders and optic atrophy

Abstract

Mitochondrial respiratory chain disorders (RCD) are a group of genetically and clinically heterogeneous diseases, caused due to defects of the respiratory chain. This study aimed to investigate the presence of common mtDNA point mutations in tRNALeu (UUR), tRNALys, MT-ATPase 6, MT-ND4, MT-ND1, MT-ND6 genes in eight Egyptian patients suspected to have
mtDNA disease and optic atrophy. PCR-RFLP analysis was done for the detection of 3243A> G, 3271T > C, 8344A> G, and 8993T >G/C mtDNA point mutations. DNA direct sequencing was pursued for the detection
of 11778G >A, 3460G > A and 14484T> C mtDNA point mutations. No point mutation of 3243A> G, 3271T > C, 8344A> G, and 8993T> G/C was detected in our group of patients. Four mtDNA polymorphisms in MT-ND1 and MT-ND4 genes (11467A > G, 11719G > A, 3348A> G and 3357G > A) were detected in three patients. Mitochondrial disorders are caused by a variety of genetic and racial factors, which differ among populations. The negative results of this study indicate that the chosen mutations might not be specific in Egyptians. Another explanation might be due to the low heteroplasmic levels of the mtDNA mutation. A registry for the different mtDNA mutations in Egyptian patients is highly recommended.