ABSTRACT
Mitochondrial mutations are responsible for at least 1% of the cases of hereditary deafness, but the contribution of each mutation has not yet been defined in African-derived or native American genetic backgrounds. A total of 203 unselected hearing-impaired patients were screened for the presence of the mitochondrial mutation A1555G in the 12S rRNA gene and mutations in the tRNASer(UCN) gene in order to assess their frequency in the ethnically admixed Brazilian population. We found four individuals with A1555G mutation (2%), which is a frequency similar to those reported for European-derived populations in unselected samples. On the other hand, complete sequencing of the tRNASer(UCN) did not reveal reported pathogenic substitutions, namely A7445G, 7472insC, T7510C, or T7511C. Instead, other rare substitutions were found such as T1291C, A7569G, and G7444A. To evaluate the significance of these findings, 110 "European-Brazilians" and 190 "African-Brazilians" unrelated hearing controls were screened. The T1291C, A7569G and G7444A substitutions were each found in about 1% (2/190) of individuals of African ancestry, suggesting that they are probably polymorphic. Our results indicate that screening for the A1555G mutation is recommended among all Brazilian deaf patients, while testing for mutations in the tRNASer(UCN) gene should be considered only when other frequent deafness-causing mutations have been excluded or in the presence of a maternal transmission pattern.
Subject(s)
Hearing Loss/genetics , Mutation/genetics , RNA, Ribosomal/genetics , RNA, Transfer, Ser/genetics , Black People/genetics , Brazil , Case-Control Studies , DNA Mutational Analysis , Female , Genetic Markers/genetics , Genetic Predisposition to Disease , Humans , Male , Pedigree , Polymerase Chain Reaction , RNA , RNA, Mitochondrial , Severity of Illness Index , White People/geneticsABSTRACT
Mitochondrial mutations are responsible for at least 1 percent of the cases of hereditary deafness, but the contribution of each mutation has not yet been defined in African-derived or native American genetic backgrounds. A total of 203 unselected hearing-impaired patients were screened for the presence of the mitochondrial mutation A1555G in the 12S rRNA gene and mutations in the tRNA Ser(UCN) gene in order to assess their frequency in the ethnically admixed Brazilian population. We found four individuals with A1555G mutation (2 percent), which is a frequency similar to those reported for European-derived populations in unselected samples. On the other hand, complete sequencing of the tRNA Ser(UCN) did not reveal reported pathogenic substitutions, namely A7445G, 7472insC, T7510C, or T7511C. Instead, other rare substitutions were found such as T1291C, A7569G, and G7444A. To evaluate the significance of these findings, 110 "European-Brazilians" and 190 "African-Brazilians" unrelated hearing controls were screened. The T1291C, A7569G and G7444A substitutions were each found in about 1 percent (2/190) of individuals of African ancestry, suggesting that they are probably polymorphic. Our results indicate that screening for the A1555G mutation is recommended among all Brazilian deaf patients, while testing for mutations in the tRNA Ser(UCN) gene should be considered only when other frequent deafness-causing mutations have been excluded or in the presence of a maternal transmission pattern.
Subject(s)
Female , Humans , Male , Hearing Loss/genetics , Mutation/genetics , RNA, Ribosomal/genetics , RNA, Transfer, Ser/genetics , Black People/genetics , Brazil , Case-Control Studies , DNA Mutational Analysis , White People/genetics , Genetic Predisposition to Disease , Genetic Markers/genetics , Pedigree , Polymerase Chain Reaction , RNA , Severity of Illness IndexABSTRACT
Since 1989, we have identified 25 patients with Lyme disease, 15 in early and 10 in latent stage, supporting its existence in Brazil, according to following reasons: 1) presence of clinical manifestations compatible with Lyme disease, with cutaneous, articular, nervous system and rarely cardiac envolvement; 2) presence of antibodies against Borrelia burgdorferi; 3) follow up of acute cases show sorologycal changes; 4) good antibiotic response at early stage of disease and only satisfactory in latent form; 5) mapping of risk areas, according to geographycal distribution of patients; 6) presence and identification of Ixodid ticks; 7) identification of micro-organism like borrelias in human, wild animals and ticks cultures, seen by dark field microscope; 8) sorology done in dogs and oxes, confirm existence of risk areas for Lyme disease.
