Objective To investigate the mutations of mitochondrial genome in a pedigree with suspected maternally inherited diabetes and deafness and to explore the correlations between the mutations and clinical features. Meth...Objective To investigate the mutations of mitochondrial genome in a pedigree with suspected maternally inherited diabetes and deafness and to explore the correlations between the mutations and clinical features. Methods Genomic DNA was isolated from blood leucocytes of each member of the pedigree. The mitochondrial genome was amplified with 24-pair primers that could cover the entire mitochondrial DNA. Direct sequencing of PCR products was used to identify any mitochondrial DNA mutations. Results Family members on the maternal side all harbored the tRNA^Lcu（UUR） A3243G mutation. The paternal side family members did not have the mutation. The age-of-onset of diabetes of the 4 maternal side family members was 15, 41, 44, and 65 years old, and their corresponding heteroplasmy level of the mutation was 34.5%, 14.9%, 14.6%, and 5.9%, respectively. The age-of-onset of diabetes and heteroplasmy level of A3243G mutation were negatively correlated with a correlation coefficient of -0.980（P=0.02）. Meanwhile, patient with high heteroplasmy level of A3243G mutation had relatively low severity of disease. Moreover, 6 reported polymorphisms and 2 new variants were found. Conclusions The main cause of diabetes in this pedigree is the tRNA^Lcu（UUR） A3243G mutation. However, other gene variants may contribute to its pathogenicity. The heteroplasmy level of the tRNA^Lcu（UUR） A3243G mutation is positively associated with earlier age-of-onset and increasing severity of diabetes.展开更多
Background: The mitochondrial DNA mutation A3302G in the tRNA Leu(UUR) gene causes respiratory chain complex I deficiency. The main clinical feature appears to be a progressive mitochondrial myopathy with proximal mus...Background: The mitochondrial DNA mutation A3302G in the tRNA Leu(UUR) gene causes respiratory chain complex I deficiency. The main clinical feature appears to be a progressive mitochondrial myopathy with proximal muscle weakness. Objective: To report on clinical and molecular features in 4 novel patients with the A3302G mutation. Design: Case reports. Patients: Four patients (3 of whom are from the same family) with a myopathy caused by the A3302G mitochondrial DNA mutation. Main Outcome Measure: Identification of the A3302G mutation by DNA sequencing. Results: All 4 patients had an adult-onset progressive mitochondrial myopathy with proximal muscle weakness, resulting in exercise intolerance. In 2 unrelated patients, upper limb reflexes were absent with preservation of at least some lower limb reflexes. Other features including hearing loss, recurrent headaches, ptosis, progressive external ophthalmoplegia, and depression were present. Conclusion: While the dominant clinical features of the A3302G mutation were exercise intolerance and proximal muscle weakness, other features of mitochondrial encephalomyopathies, previously not described for this mutation, were present.展开更多
文摘Objective To investigate the mutations of mitochondrial genome in a pedigree with suspected maternally inherited diabetes and deafness and to explore the correlations between the mutations and clinical features. Methods Genomic DNA was isolated from blood leucocytes of each member of the pedigree. The mitochondrial genome was amplified with 24-pair primers that could cover the entire mitochondrial DNA. Direct sequencing of PCR products was used to identify any mitochondrial DNA mutations. Results Family members on the maternal side all harbored the tRNA^Lcu（UUR） A3243G mutation. The paternal side family members did not have the mutation. The age-of-onset of diabetes of the 4 maternal side family members was 15, 41, 44, and 65 years old, and their corresponding heteroplasmy level of the mutation was 34.5%, 14.9%, 14.6%, and 5.9%, respectively. The age-of-onset of diabetes and heteroplasmy level of A3243G mutation were negatively correlated with a correlation coefficient of -0.980（P=0.02）. Meanwhile, patient with high heteroplasmy level of A3243G mutation had relatively low severity of disease. Moreover, 6 reported polymorphisms and 2 new variants were found. Conclusions The main cause of diabetes in this pedigree is the tRNA^Lcu（UUR） A3243G mutation. However, other gene variants may contribute to its pathogenicity. The heteroplasmy level of the tRNA^Lcu（UUR） A3243G mutation is positively associated with earlier age-of-onset and increasing severity of diabetes.
文摘Background: The mitochondrial DNA mutation A3302G in the tRNA Leu(UUR) gene causes respiratory chain complex I deficiency. The main clinical feature appears to be a progressive mitochondrial myopathy with proximal muscle weakness. Objective: To report on clinical and molecular features in 4 novel patients with the A3302G mutation. Design: Case reports. Patients: Four patients (3 of whom are from the same family) with a myopathy caused by the A3302G mitochondrial DNA mutation. Main Outcome Measure: Identification of the A3302G mutation by DNA sequencing. Results: All 4 patients had an adult-onset progressive mitochondrial myopathy with proximal muscle weakness, resulting in exercise intolerance. In 2 unrelated patients, upper limb reflexes were absent with preservation of at least some lower limb reflexes. Other features including hearing loss, recurrent headaches, ptosis, progressive external ophthalmoplegia, and depression were present. Conclusion: While the dominant clinical features of the A3302G mutation were exercise intolerance and proximal muscle weakness, other features of mitochondrial encephalomyopathies, previously not described for this mutation, were present.
