Screening of mitochondrial mutations in Tunisian patients with mitochondrial disorders: An overview study

To investigate the spectrum of common mitochondrial mutations in Tunisia during the years of 2002-2012, 226 patients with mitochondrial disorders were clinically diagnosed with hearing loss, Leigh syndrome (LS), diabetes, cardiomyopathy, Kearns-Sayre syndrome (KSS), Pearson syndrome (PS), myopathy, mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes syndrome (MELAS) and Wolfram syndrome. Restriction fragment length polymorphism (PCR-RFLP), radioactive PCR, single specific primer-PCR (SSP-PCR) analysis and PCR-sequencing methods were used to identify the mutations. Two cases with m. 1555A > G mutation and two families with the novel 12S rRNA m. 735A > G transition were detected in patients with hearing loss. Three cases with m. 8993T > G mutation, two patients with the novel m. 5523T > G and m. 5559A > G mutations in the tRNA(Trp) gene, and two individuals with the undescribed m. 9478T > C mutation in the cytochrome c oxidase subunit III (COXIII) gene were found with LS. In addition, one case with hypertrophic cardiomyopathy and deafness presented the ND1 m. 3395A > G mutation and the tRNA(Ile) m.4316A > G variation. Besides, multiple mitochondrial deletions were detected in patients with KSS, PS, and Wolfram syndrome. The m. 14709T > C mutation in the tRNA(Glu) was reported in four maternally inherited diabetes and deafness patients and a novel tRNA(Val) m. 1640A > G mutation was detected in a MELAS patient.