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Fussiger H, Saraiva-Pereira ML, Leistner-Segal S, Jardim LB. Friedreich Ataxia: Diagnostic Yield and Minimal Frequency in South Brazil. CEREBELLUM (LONDON, ENGLAND) 2019; 18:147-151. [PMID: 29938355 DOI: 10.1007/s12311-018-0958-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
Friedreich ataxia (FRDA) is an autosomal recessive disorder due to mutations in the FXN gene. FRDA is characterized by the classical triad of ataxia, absent reflexes, and Babinski sign, but atypical presentations might also occur. Our aims were to describe the proportion of FRDA diagnoses in suspected families living in Rio Grande do Sul, South Brazil, and to estimate a minimum frequency of symptomatic subjects. Subjects that were evaluated by molecular analysis for FRDA at the Hospital de Clínicas de Porto Alegre were identified in our files. Patients' clinical manifestation and phenotypes were described and compared. The number of FRDA subjects alive in the last 5 years was determined. One hundred fifty-six index cases (families) were submitted to evaluation of GAA repeats at FXN since 1997: 27 were confirmed as FRDA patients. Therefore, the diagnostic yield was 17.3%. Proportion of classical, late onset, and retained reflexes subphenotypes were similar to those described by other studies. A minimum prevalence was estimated as 0.20:100.000 inhabitants. In conclusion, we verified that this FRDA population displayed the usual clinical characteristics, but with a lower period prevalence than those obtained in populations from Europe.
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Affiliation(s)
- Helena Fussiger
- Programa de Pós-Graduação em Saúde da Criança e do Adolescente, Universidade Federal do Rio Grande do Sul, Rua Ramiro Barcelos, 2400, sala 220, Porto Alegre, 90035-003, Brazil
| | - Maria Luiza Saraiva-Pereira
- Departamento de Bioquímica, Universidade Federal do Rio Grande do Sul, Rua Ramiro Barcelos, 2600-Prédio Anexo, Porto Alegre, 90035-003, Brazil
- Laboratório de Identificação Genética, Centro de Pesquisa Experimental, Hospital de Clínicas de Porto Alegre, Rua Ramiro Barcelos 2350, Porto Alegre, 90035-003, Brazil
- Serviço de Genética Médica, Hospital de Clínicas de Porto Alegre, Rua Ramiro Barcelos 2350, Porto Alegre, 90035-003, Brazil
| | - Sandra Leistner-Segal
- Programa de Pós-Graduação em Saúde da Criança e do Adolescente, Universidade Federal do Rio Grande do Sul, Rua Ramiro Barcelos, 2400, sala 220, Porto Alegre, 90035-003, Brazil
- Serviço de Genética Médica, Hospital de Clínicas de Porto Alegre, Rua Ramiro Barcelos 2350, Porto Alegre, 90035-003, Brazil
| | - Laura Bannach Jardim
- Programa de Pós-Graduação em Saúde da Criança e do Adolescente, Universidade Federal do Rio Grande do Sul, Rua Ramiro Barcelos, 2400, sala 220, Porto Alegre, 90035-003, Brazil.
- Laboratório de Identificação Genética, Centro de Pesquisa Experimental, Hospital de Clínicas de Porto Alegre, Rua Ramiro Barcelos 2350, Porto Alegre, 90035-003, Brazil.
- Serviço de Genética Médica, Hospital de Clínicas de Porto Alegre, Rua Ramiro Barcelos 2350, Porto Alegre, 90035-003, Brazil.
- Departamento de Medicina Interna, Universidade Federal do Rio Grande do Sul, Rua Ramiro Barcelos 2350, Porto Alegre, 90035-003, Brazil.
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Alarcón-Riquelme ME, Ziegler JT, Molineros J, Howard TD, Moreno-Estrada A, Sánchez-Rodríguez E, Ainsworth HC, Ortiz-Tello P, Comeau ME, Rasmussen A, Kelly JA, Adler A, Acevedo-Vázquez EM, Cucho-Venegas JM, García-De la Torre I, Cardiel MH, Miranda P, Catoggio LJ, Maradiaga-Ceceña M, Gaffney PM, Vyse TJ, Criswell LA, Tsao BP, Sivils KL, Bae SC, James JA, Kimberly RP, Kaufman KM, Harley JB, Esquivel-Valerio JA, Moctezuma JF, García MA, Berbotto GA, Babini AM, Scherbarth H, Toloza S, Baca V, Nath SK, Aguilar Salinas C, Orozco L, Tusié-Luna T, Zidovetzki R, Pons-Estel BA, Langefeld CD, Jacob CO. Genome-Wide Association Study in an Amerindian Ancestry Population Reveals Novel Systemic Lupus Erythematosus Risk Loci and the Role of European Admixture. Arthritis Rheumatol 2016; 68:932-43. [PMID: 26606652 DOI: 10.1002/art.39504] [Citation(s) in RCA: 112] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2015] [Accepted: 11/03/2015] [Indexed: 12/21/2022]
Abstract
OBJECTIVE Systemic lupus erythematosus (SLE) is a chronic autoimmune disease with a strong genetic component. We undertook the present work to perform the first genome-wide association study on individuals from the Americas who are enriched for Native American heritage. METHODS We analyzed 3,710 individuals from the US and 4 countries of Latin America who were diagnosed as having SLE, and healthy controls. Samples were genotyped with HumanOmni1 BeadChip. Data on out-of-study controls genotyped with HumanOmni2.5 were also included. Statistical analyses were performed using SNPtest and SNPGWA. Data were adjusted for genomic control and false discovery rate. Imputation was performed using Impute2 and, for classic HLA alleles, HiBag. Odds ratios (ORs) and 95% confidence intervals (95% CIs) were calculated. RESULTS The IRF5-TNPO3 region showed the strongest association and largest OR for SLE (rs10488631: genomic control-adjusted P [Pgcadj ] = 2.61 × 10(-29), OR 2.12 [95% CI 1.88-2.39]), followed by HLA class II on the DQA2-DQB1 loci (rs9275572: Pgcadj = 1.11 × 10(-16), OR 1.62 [95% CI 1.46-1.80] and rs9271366: Pgcadj = 6.46 × 10(-12), OR 2.06 [95% CI 1.71-2.50]). Other known SLE loci found to be associated in this population were ITGAM, STAT4, TNIP1, NCF2, and IRAK1. We identified a novel locus on 10q24.33 (rs4917385: Pgcadj = 1.39 × 10(-8)) with an expression quantitative trait locus (eQTL) effect (Peqtl = 8.0 × 10(-37) at USMG5/miR1307), and several new suggestive loci. SLE risk loci previously identified in Europeans and Asians were corroborated. Local ancestry estimation showed that the HLA allele risk contribution is of European ancestral origin. Imputation of HLA alleles suggested that autochthonous Native American haplotypes provide protection against development of SLE. CONCLUSION Our results demonstrate that studying admixed populations provides new insights in the delineation of the genetic architecture that underlies autoimmune and complex diseases.
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Affiliation(s)
| | - Julie T Ziegler
- Wake Forest School of Medicine, Winston-Salem, North Carolina
| | | | | | - Andrés Moreno-Estrada
- Stanford University School of Medicine, Stanford, California, and Laboratorio Nacional de Genómica para la Biodiversidad, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Irapuato, Mexico
| | | | | | - Patricia Ortiz-Tello
- Stanford University School of Medicine, Stanford, California, and Laboratorio Nacional de Genómica para la Biodiversidad, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Irapuato, Mexico
| | - Mary E Comeau
- Wake Forest School of Medicine, Winston-Salem, North Carolina
| | | | | | - Adam Adler
- Oklahoma Medical Research Foundation, Oklahoma City
| | | | | | | | | | | | | | | | | | | | | | | | | | - Sang-Cheol Bae
- Hanyang University Hospital for Rheumatic Diseases, Seoul, Republic of Korea
| | - Judith A James
- Oklahoma Medical Research Foundation and University of Oklahoma Health Sciences Center, Oklahoma City
| | | | | | - John B Harley
- Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio
| | - Jorge A Esquivel-Valerio
- Hospital Universitario Dr. José Eleuterio González Universidad Autonoma de Nuevo León, Monterrey, Mexico
| | | | - Mercedes A García
- Hospital Interzonal General de Agudos General San Martin, La Plata, Argentina
| | | | | | - Hugo Scherbarth
- Hospital Interzonal General de Agudos Oscar E. Alende, Mar del Plata, Argentina
| | - Sergio Toloza
- Hospital Interzonal San Juan Bautista, San Fernando del Valle de Catamarca, Argentina
| | - Vicente Baca
- Hospital de Peditaria, Centro Médico Nacional Siglo XXI, Instituto Mexicano del Seguro Social, Mexico City, Mexico
| | | | - Carlos Aguilar Salinas
- Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Mexico City, Mexico
| | - Lorena Orozco
- Instituto Nacional de Medicina Genómica, Mexico City, Mexico
| | - Teresa Tusié-Luna
- Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán and Instituto de Investigaciones Biomédicas de la Universidad Nacional Autónoma de México, Mexico City, Mexico
| | | | | | | | - Chaim O Jacob
- University of Southern California School of Medicine, Los Angeles
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Flores-Martínez SE, Castro-Martínez AG, López-Quintero A, García-Zapién AG, Torres-Rodríguez RN, Sánchez-Corona J. [Association analysis of SNP-63 and indel-19 variant in the calpain-10 gene with polycystic ovary syndrome in women of reproductive age]. CIR CIR 2015; 83:35-42. [PMID: 25982606 DOI: 10.1016/j.circir.2015.04.021] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2013] [Accepted: 08/04/2014] [Indexed: 11/25/2022]
Abstract
BACKGROUND Polycystic ovary syndrome is a complex and heterogeneous disease involving both reproductive and metabolic problems. It has been suggested a genetic predisposition in the etiology of this syndrome. The identification of calpain-10 gene (CAPN10) as the first candidate gene for type 2 diabetes mellitus, has focused the interest in investigating their possible relation with the polycystic ovary syndrome, because this syndrome is associated with hyperinsulinemia and insulin resistance, two metabolic abnormalities associated with type 2 diabetes mellitus. OBJECTIVE To investigate if there is association between the SNP-63 and the variant indel-19 of the CAPN10 gene and polycystic ovary syndrome in women of reproductive age. MATERIAL AND METHODS This study included 101 women (55 with polycystic ovary syndrome and 46 without polycystic ovary syndrome). The genetic variant indel-19 was identified by electrophoresis of the amplified fragments by PCR, and the SNP-63 by PCR-RFLP. RESULTS The allele and genotype frequencies of the two variants do not differ significatly between women with polycystic ovary syndrome and control women group. The haplotype 21 (defined by the insertion allele of indel-19 variant and C allele of SNP-63) was found with higher frequency in both study groups, being more frequent in the polycystic ovary syndrome patients group, however, this difference was not statistically significant (p = 0.8353). CONCLUSIONS The results suggest that SNP-63 and indel-19 variant of the CAPN10 gene do not represent a risk factor for polycystic ovary syndrome in our patients group.
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Affiliation(s)
- Silvia Esperanza Flores-Martínez
- División de Medicina Molecular, Centro de Investigación Biomédica de Occidente, Instituto Mexicano del Seguro Social, Guadalajara, Jalisco, México
| | - Anna Gabriela Castro-Martínez
- División de Medicina Molecular, Centro de Investigación Biomédica de Occidente, Instituto Mexicano del Seguro Social, Guadalajara, Jalisco, México
| | - Andrés López-Quintero
- División de Medicina Molecular, Centro de Investigación Biomédica de Occidente, Instituto Mexicano del Seguro Social, Guadalajara, Jalisco, México
| | - Alejandra Guadalupe García-Zapién
- Departamento de Farmacobiología, Centro Universitario de Ciencias Exactas e Ingenierías, Universidad de Guadalajara, Guadalajara, Jalisco, México
| | - Ruth Noemí Torres-Rodríguez
- División de Medicina Molecular, Centro de Investigación Biomédica de Occidente, Instituto Mexicano del Seguro Social, Guadalajara, Jalisco, México
| | - José Sánchez-Corona
- División de Medicina Molecular, Centro de Investigación Biomédica de Occidente, Instituto Mexicano del Seguro Social, Guadalajara, Jalisco, México.
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Sánchez E, Rasmussen A, Riba L, Acevedo-Vasquez E, Kelly JA, Langefeld CD, Williams AH, Ziegler JT, Comeau ME, Marion MC, García-De La Torre I, Maradiaga-Ceceña MA, Cardiel MH, Esquivel-Valerio JA, Rodriguez-Amado J, Moctezuma JF, Miranda P, Perandones CE, Castel C, Laborde HA, Alba P, Musuruana JL, Goecke IA, Anaya JM, Kaufman KM, Adler A, Glenn SB, Brown EE, Alarcón GS, Kimberly RP, Edberg JC, Vilá LM, Criswell LA, Gilkeson GS, Niewold TB, Martín J, Vyse TJ, Boackle SA, Ramsey-Goldman R, Scofield RH, Petri M, Merrill JT, Reveille JD, Tsao BP, Orozco L, Baca V, Moser KL, Gaffney PM, James JA, Harley JB, Tusié-Luna T, Pons-Estel BA, Jacob CO, Alarcón-Riquelme ME. Impact of genetic ancestry and sociodemographic status on the clinical expression of systemic lupus erythematosus in American Indian-European populations. ACTA ACUST UNITED AC 2013; 64:3687-94. [PMID: 22886787 DOI: 10.1002/art.34650] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
OBJECTIVE American Indian-Europeans, Asians, and African Americans have an excess morbidity from systemic lupus erythematosus (SLE) and a higher prevalence of lupus nephritis than do Caucasians. The aim of this study was to analyze the relationship between genetic ancestry and sociodemographic characteristics and clinical features in a large cohort of American Indian-European SLE patients. METHODS A total of 2,116 SLE patients of American Indian-European origin and 4,001 SLE patients of European descent for whom we had clinical data were included in the study. Genotyping of 253 continental ancestry-informative markers was performed on the Illumina platform. Structure and Admixture software were used to determine genetic ancestry proportions of each individual. Logistic regression was used to test the association between genetic ancestry and sociodemographic and clinical characteristics. Odds ratios (ORs) were calculated with 95% confidence intervals (95% CIs). RESULTS The average American Indian genetic ancestry of 2,116 SLE patients was 40.7%. American Indian genetic ancestry conferred increased risks of renal involvement (P < 0.0001, OR 3.50 [95% CI 2.63- 4.63]) and early age at onset (P < 0.0001). American Indian ancestry protected against photosensitivity (P < 0.0001, OR 0.58 [95% CI 0.44-0.76]), oral ulcers (P < 0.0001, OR 0.55 [95% CI 0.42-0.72]), and serositis (P < 0.0001, OR 0.56 [95% CI 0.41-0.75]) after adjustment for age, sex, and age at onset. However, age and sex had stronger effects than genetic ancestry on malar rash, discoid rash, arthritis, and neurologic involvement. CONCLUSION In general, American Indian genetic ancestry correlates with lower sociodemographic status and increases the risk of developing renal involvement and SLE at an earlier age.
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Affiliation(s)
- Elena Sánchez
- Oklahoma Medical Research Foundation, Oklahoma City, USA
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Yescas P, López M, Monroy N, Boll MC, Rodríguez-Violante M, Rodríguez U, Ochoa A, Alonso ME. Low frequency of common LRRK2 mutations in Mexican patients with Parkinson's disease. Neurosci Lett 2010; 485:79-82. [PMID: 20727385 DOI: 10.1016/j.neulet.2010.08.029] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2010] [Revised: 08/04/2010] [Accepted: 08/10/2010] [Indexed: 11/19/2022]
Abstract
Mutations in leucine-rich repeat kinase 2 gene (LRRK2) account for as much as 5-6% of familial Parkinson's disease (PD) and 1-2% of sporadic PD. These mutations represent the most frequent cause of autosomal dominant PD, particularly in certain ethnic groups. In this first report concerning LRRK2 mutations in Mexican-mestizos, we screened 319 consecutive PD patients (186 males; 133 females; mean age at onset: 52.4 years) for LRRK2 mutations in exons 31 and 41 and for the mutation in exon 35, which produces the Y1699C substitution. Three (0.94%) patients, two with sporadic PD and one with familial PD (disease mean age at onset, 53.3 years), were heterozygous for LRRK2 mutations. Of these three, two patients had one of two different mutations in exon 31 (R1441G and R1441H, respectively); the other patient carried the G2019S mutation in exon 41. The Y1699C mutation was absent from this PD sample. Four additional subjects, unaffected relatives of one PD patient with a mutation in LRRK2, were subsequently genetically tested. None of the three LRRK2 mutations identified was present in 200 neurologically healthy Mexican control individuals. These findings have important implications for molecular testing of LRRK2 mutations in Mexican PD patients.
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Affiliation(s)
- Petra Yescas
- Department of Neurogenetics and Molecular Biology, Instituto Nacional de Neurología y Neurocirugía Manuel Velasco Suárez, Insurgentes Sur 3877, Col. La Fama, Tlalpan, 14269 Mexico City, D.F., Mexico
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Mariño TC, Zaldivar YG, Mesa JML, Mederos LA, Rodríguez RA, Gotay DA, Labrada RR, Ochoa NC, Macleod P, Pérez LV. Low predisposition to instability of the Friedreich ataxia gene in Cuban population. Clin Genet 2010; 77:598-600. [PMID: 20569261 DOI: 10.1111/j.1399-0004.2009.01361.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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Singh I, Faruq M, Mukherjee O, Jain S, Pal PK, Srivastav MVP, Behari M, Srivastava AK, Mukerji M. North and South Indian Populations Share a Common Ancestral Origin of Friedreich's Ataxia but Vary in Age of GAA Repeat Expansion. Ann Hum Genet 2010; 74:202-10. [DOI: 10.1111/j.1469-1809.2010.00569.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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Alonso E, Martínez-Ruano L, De Biase I, Mader C, Ochoa A, Yescas P, Gutiérrez R, White M, Ruano L, Fragoso-Benítez M, Ashizawa T, Bidichandani SI, Rasmussen A. Distinct distribution of autosomal dominant spinocerebellar ataxia in the Mexican population. Mov Disord 2007; 22:1050-3. [PMID: 17427938 DOI: 10.1002/mds.21470] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Dominant ataxias show wide geographic variation. We analyzed 108 dominant families and 123 sporadic ataxia patients from Mexico for mutations causing SCA1-3, 6-8, 10, 12, 17 and DRPLA. Only 18.5% of dominant families remained undiagnosed; SCA2 accounted for half (45.4%), followed by SCA10 (13.9%), SCA3 (12%), SCA7 (7.4%), and SCA17 (2.8%). None had SCA1, 6, 8, 12 or DRPLA. Among sporadic cases, 6 had SCA2 (4.9%), and 2 had SCA17 (1.6%). In the SCA2 patients we identified 6 individuals with the rare (CAG)(33) allele, 2 of whom showed early onset ataxia. The distribution of dominant ataxia mutations in Mexicans is distinct from other populations.
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Affiliation(s)
- Elisa Alonso
- Department of Neurogenetics and Molecular Biology, Instituto Nacional de Neurología y Neurocirugía Manuel Velasco Suárez, Mexico City, Mexico
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López M, Guerrero J, Yescas P, Boll MC, Familiar I, Ochoa A, Rasmussen A, Alonso ME. Apolipoprotein E epsilon4 allele is associated with Parkinson disease risk in a Mexican Mestizo population. Mov Disord 2007; 22:417-20. [PMID: 17230455 DOI: 10.1002/mds.21340] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
We investigated the association between apolipoprotein E (APOE) alleles and genotypes and Parkinson disease (PD) in 229 unrelated Mexican Mestizo PD patients and 229 controls. Results showed that both APOE-epsilon4 allele and APOE epsilon4/epsilon3 genotype are associated with PD (OR = 1.736, P = 0.011; OR = 1.688, P = 0.019, respectively). Mean age at onset of PD was not associated to any APOE allele or genotype, but was significantly earlier in familial PD when compared to sporadic cases (P = 0.025).
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Affiliation(s)
- Marisol López
- Department of Biological Systems, Universidad Autónoma Metropolitana Xochimilco, Mexico City, Mexico
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Rasmussen A, Gómez M, Alonso E, Bidichandani SI. Clinical heterogeneity of recessive ataxia in the Mexican population. J Neurol Neurosurg Psychiatry 2006; 77:1370-2. [PMID: 17110750 PMCID: PMC2077434 DOI: 10.1136/jnnp.2006.090449] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/09/2006] [Revised: 04/15/2006] [Accepted: 07/21/2006] [Indexed: 11/03/2022]
Abstract
Approximately 75% of Indo-European patients with recessive ataxia are homozygous for frataxin gene (FXN) mutations and have either typical or atypical Friedreich ataxia (FRDA). Our previous analysis of 134 Mexican Mestizo recessive ataxia patients showed that FRDA is relatively uncommon in the Mexican population (10.4%). This article reports the evaluation of the phenotypes of these patients. Over half of the patients with clinical diagnostic criteria for FRDA did not carry FXN mutations, constituting a "FRDA-like" phenotypic subgroup. Analysis of non-FRDA patients revealed a subgroup with early onset recessive cerebellar ataxia and cognitive deficit. These two phenotypic subgroups accounted for approximately 60% of all patients, indicating that the cause for recessive ataxia in the Mexican population is distinct from other populations and remains largely unknown.
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Affiliation(s)
- A Rasmussen
- Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, 975 NE, 10th St, Oklahoma City, OK 73104, USA
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Clark RM, Bhaskar SS, Miyahara M, Dalgliesh GL, Bidichandani SI. Expansion of GAA trinucleotide repeats in mammals. Genomics 2005; 87:57-67. [PMID: 16316739 DOI: 10.1016/j.ygeno.2005.09.006] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2005] [Revised: 09/04/2005] [Accepted: 09/07/2005] [Indexed: 01/29/2023]
Abstract
We have previously shown that GAA trinucleotide repeats have undergone significant expansion in the human genome. Here we present the analysis of the length distribution of all 10 nonredundant trinucleotide repeat motifs in 20 complete eukaryotic genomes (6 mammalian, 2 nonmammalian vertebrates, 4 arthropods, 4 fungi, and 1 each of nematode, amoebozoa, alveolate, and plant), which showed that the abundance of large expansions of GAA trinucleotide repeats is specific to mammals. Analysis of human-chimpanzee-gorilla orthologs revealed that loci with large expansions are species-specific and have occurred after divergence from the common ancestor. PCR analysis of human controls revealed large expansions at multiple human (GAA)(30+) loci; nine loci showed expanded alleles containing >65 triplets, analogous to disease-causing expansions in Friedreich ataxia, including two that are in introns of genes of unknown function. The abundance of long GAA trinucleotide repeat tracts in mammalian genomes represents a significant mutation potential and source of interindividual variability.
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Affiliation(s)
- Rhonda M Clark
- Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
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