Pub Date : 1997-12-01DOI: 10.1590/S0100-84551997000400029
G. B. Marin, M. Tavella, J. Guerreiro, S. Santos, M. Zago
Determination of the ApoE allele distribution in five South American Amerindian tribes revealed absence of the ApoE2 allele, accompanied by high ApoE3 and low ApoE4 allele frequencies for most tribes, a distribution only previously reported for the Inuit Eskimo from Greenland.
{"title":"Absence of the E2 allele of apolipoprotein in Amerindians","authors":"G. B. Marin, M. Tavella, J. Guerreiro, S. Santos, M. Zago","doi":"10.1590/S0100-84551997000400029","DOIUrl":"https://doi.org/10.1590/S0100-84551997000400029","url":null,"abstract":"Determination of the ApoE allele distribution in five South American Amerindian tribes revealed absence of the ApoE2 allele, accompanied by high ApoE3 and low ApoE4 allele frequencies for most tribes, a distribution only previously reported for the Inuit Eskimo from Greenland.","PeriodicalId":340356,"journal":{"name":"Brazilian Journal of Genetics","volume":"27 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125838249","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1997-12-01DOI: 10.1590/S0100-84551997000400012
B. Vidal, S. S. Maria, L. B. Klaczko
A capacidade de ligacao da concanavalina A (Con A) a regioes condensadas de eucromatina e heterocromatina foi investigada em nucleos de eritrocito de frango (CEN), hepatocitos de rato, celulas meristematicas de Zea mays mays e em cromossomos politenicos de Drosophila melanogaster apos hidrolise com HCl 4 N para determinar a ocorrencia de ligacao preferencial em bandas e heterocromatina. A variacao da massa seca foi investigada em CEN por microscopia de interferencia, e reacoes de Feulgen e Con A foram empregadas para todos os materiais para correlacionar os loci de ambas reacoes. As quantificacoes e verificacoes topologicas foram levadas a efeito por analise de imagens (citometria de alta performance). Foi observado que a hidrolise por HCl 4 N causou uma importante perda de massa seca em CEN, permanecendo um nivel correspondente ao conteudo medio de massa seca de DNA. Neste material a ligacao com Con A foi restrita ao envelope nuclear, reforcando a ideia da ausencia da matriz nuclear nessas celulas. Os demais tipos celulares exibiram areas reativas de cromatina condensada e heterocromatina. Este fato permite especular o papel desempenhado por proteinas Con A-positivas no mecanismo de condensacao cromatinica. Esta estrutura glicoproteica contribuiria para uma maior estabilidade fisico-quimica da cromatina condensada, especificamente da heterocromatina, e tambem para suas propriedades reologicas.
{"title":"Concanavalin A-reactive nuclear matrix glycoprotein","authors":"B. Vidal, S. S. Maria, L. B. Klaczko","doi":"10.1590/S0100-84551997000400012","DOIUrl":"https://doi.org/10.1590/S0100-84551997000400012","url":null,"abstract":"A capacidade de ligacao da concanavalina A (Con A) a regioes condensadas de eucromatina e heterocromatina foi investigada em nucleos de eritrocito de frango (CEN), hepatocitos de rato, celulas meristematicas de Zea mays mays e em cromossomos politenicos de Drosophila melanogaster apos hidrolise com HCl 4 N para determinar a ocorrencia de ligacao preferencial em bandas e heterocromatina. A variacao da massa seca foi investigada em CEN por microscopia de interferencia, e reacoes de Feulgen e Con A foram empregadas para todos os materiais para correlacionar os loci de ambas reacoes. As quantificacoes e verificacoes topologicas foram levadas a efeito por analise de imagens (citometria de alta performance). Foi observado que a hidrolise por HCl 4 N causou uma importante perda de massa seca em CEN, permanecendo um nivel correspondente ao conteudo medio de massa seca de DNA. Neste material a ligacao com Con A foi restrita ao envelope nuclear, reforcando a ideia da ausencia da matriz nuclear nessas celulas. Os demais tipos celulares exibiram areas reativas de cromatina condensada e heterocromatina. Este fato permite especular o papel desempenhado por proteinas Con A-positivas no mecanismo de condensacao cromatinica. Esta estrutura glicoproteica contribuiria para uma maior estabilidade fisico-quimica da cromatina condensada, especificamente da heterocromatina, e tambem para suas propriedades reologicas.","PeriodicalId":340356,"journal":{"name":"Brazilian Journal of Genetics","volume":"40 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126766784","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1997-12-01DOI: 10.1590/S0100-84551997000400014
S. M. M. Dantas, R. Barros
Oito subespecies do genero Saguinus (S. f. fuscicollis, S. f. weddelli, S. b. bicolor, S. b. martinsi, S. m. mystax, S. i. imperator, S. m. midas e S. m. niger) foram estudadas citogeneticamente, das quais cinco (S. f. fuscicollis, S. f. weddelli, S. b. martinsi, S. m. mystax e S. i. imperator) tiveram seu cariotipo descrito pela primeira vez neste estudo. Os cariotipos foram analisados por coloracao convencional, pelos padroes de bandas G, C e NOR, e pelo metodo de bandeamento sequencial G/C. Todos os especimens mostraram o mesmo numero diploide (2n = 46 cromossomos) e os padroes de bandas G, C e NOR foram muito similares entre as subespecies, diferindo apenas na quantidade e distribuicao de heterocromatina constitutiva de alguns autossomos. Heterocromatina constitutiva presente na regiao telomerica de alguns cromossomos foi observada apenas em S. f. fuscicollis e S. f. weddelli. O cromossomo X foi igual em todas subespecies, porem, o cromossomo Y diferiu em morfologia e tamanho. Quimerismo cromossomico XX/XY foi verificado em todas as subespecies.
八subespecies是什么样的(f s f . fuscicollis weddelli s b . b . martinsi双色的,s m ia mystax,最高统治者,s m(和尼日尔).研究了citogeneticamente,其中五(s . f . fuscicollis, b s f . weddelli martinsi s.m.k mystax和ia最高统治者)的cariotipo第一次描述了这项研究。核型采用常规染色、G、C、NOR条带模式和G/C顺序条带法进行分析。所有标本的二倍体数目相同(2n = 46条染色体)，G、C和NOR带模式在亚种间非常相似，只是在某些常染色体组成异染色质的数量和分布上有所不同。在某些染色体的端粒区存在结构性异染色质，仅在fuscicollis和weddelli中观察到。所有亚种的X染色体相同，而Y染色体的形态和大小不同。所有亚种均存在染色体嵌合XX/XY。
{"title":"Cytogenetic study of the genus Saguinus (Callithrichidae, Primates)","authors":"S. M. M. Dantas, R. Barros","doi":"10.1590/S0100-84551997000400014","DOIUrl":"https://doi.org/10.1590/S0100-84551997000400014","url":null,"abstract":"Oito subespecies do genero Saguinus (S. f. fuscicollis, S. f. weddelli, S. b. bicolor, S. b. martinsi, S. m. mystax, S. i. imperator, S. m. midas e S. m. niger) foram estudadas citogeneticamente, das quais cinco (S. f. fuscicollis, S. f. weddelli, S. b. martinsi, S. m. mystax e S. i. imperator) tiveram seu cariotipo descrito pela primeira vez neste estudo. Os cariotipos foram analisados por coloracao convencional, pelos padroes de bandas G, C e NOR, e pelo metodo de bandeamento sequencial G/C. Todos os especimens mostraram o mesmo numero diploide (2n = 46 cromossomos) e os padroes de bandas G, C e NOR foram muito similares entre as subespecies, diferindo apenas na quantidade e distribuicao de heterocromatina constitutiva de alguns autossomos. Heterocromatina constitutiva presente na regiao telomerica de alguns cromossomos foi observada apenas em S. f. fuscicollis e S. f. weddelli. O cromossomo X foi igual em todas subespecies, porem, o cromossomo Y diferiu em morfologia e tamanho. Quimerismo cromossomico XX/XY foi verificado em todas as subespecies.","PeriodicalId":340356,"journal":{"name":"Brazilian Journal of Genetics","volume":"98 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134552473","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1997-12-01DOI: 10.1590/S0100-84551997000400018
W. J. Miller
{"title":"Dominance, codominance and epistasis","authors":"W. J. Miller","doi":"10.1590/S0100-84551997000400018","DOIUrl":"https://doi.org/10.1590/S0100-84551997000400018","url":null,"abstract":"","PeriodicalId":340356,"journal":{"name":"Brazilian Journal of Genetics","volume":"21 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134033858","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1997-12-01DOI: 10.1590/S0100-84551997000400009
M. D. P. Acedo, G. Paranhos-Baccalà, C. Denoya, I. R. Ruiz
The a-globin major genes from diploid and tetraploid Odontophrynus americanus were studied using PCR-based technology. The cloned and sequenced amplified fragments were shown to contain most of the exon II sequences as well as the whole exon III sequence of the a-globin gene. Unexpectedly, intron 2 was entirely absent in the amplified fragments of both 2n and 4n origin. High conservation was observed among the obtained sequences when compared to corresponding sequences from human and Xenopus laevis origin. The possibility that these sequences might be pseudogenes is raised
{"title":"Molecular cloning of exons II and III of the a -globin major gene from Odontophrynus americanus 2n and 4n (Amphibia, Anura)","authors":"M. D. P. Acedo, G. Paranhos-Baccalà, C. Denoya, I. R. Ruiz","doi":"10.1590/S0100-84551997000400009","DOIUrl":"https://doi.org/10.1590/S0100-84551997000400009","url":null,"abstract":"The a-globin major genes from diploid and tetraploid Odontophrynus americanus were studied using PCR-based technology. The cloned and sequenced amplified fragments were shown to contain most of the exon II sequences as well as the whole exon III sequence of the a-globin gene. Unexpectedly, intron 2 was entirely absent in the amplified fragments of both 2n and 4n origin. High conservation was observed among the obtained sequences when compared to corresponding sequences from human and Xenopus laevis origin. The possibility that these sequences might be pseudogenes is raised","PeriodicalId":340356,"journal":{"name":"Brazilian Journal of Genetics","volume":"18 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127076857","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1997-12-01DOI: 10.1590/S0100-84551997000400015
D. Selivon, A. Perondini
Methods previously described by Canovai et al. (Caryologia 47: 241-247, 1994) which produced C and ASG bands in mitotic chromosomes of Ceratitis capitata were applied to the chromosomes of several Anastrepha species. Metaphase plate yield was substantially increased by use of imaginal disks together with cerebral ganglia. The C-bands were quite prominent allowing the resolution of tiny blocks of heterochromatin. The ASG method produced G-like banded chromosomes, which permitted recognition of each individual chromosome. These simple techniques do not require special equipment and may be valuable for karyotype variability studies in fruit flies and other Diptera
Canovai et al. (Caryologia 47: 241-247, 1994)先前描述的在头角certis有丝分裂染色体中产生C和ASG带的方法应用于几个Anastrepha物种的染色体。与神经节一起使用影像盘可显著增加中期钢板产量。c波段非常突出，可以分辨出微小的异染色质块。ASG方法产生g样带状染色体，允许识别每个单独的染色体。这些简单的技术不需要特殊的设备，可能对果蝇和其他双翅目生物的核型变异研究有价值
{"title":"Evaluation of techniques for C and ASG banding of the mitotic chromosomes of Anastrepha species (Diptera, Tephritidae)","authors":"D. Selivon, A. Perondini","doi":"10.1590/S0100-84551997000400015","DOIUrl":"https://doi.org/10.1590/S0100-84551997000400015","url":null,"abstract":"Methods previously described by Canovai et al. (Caryologia 47: 241-247, 1994) which produced C and ASG bands in mitotic chromosomes of Ceratitis capitata were applied to the chromosomes of several Anastrepha species. Metaphase plate yield was substantially increased by use of imaginal disks together with cerebral ganglia. The C-bands were quite prominent allowing the resolution of tiny blocks of heterochromatin. The ASG method produced G-like banded chromosomes, which permitted recognition of each individual chromosome. These simple techniques do not require special equipment and may be valuable for karyotype variability studies in fruit flies and other Diptera","PeriodicalId":340356,"journal":{"name":"Brazilian Journal of Genetics","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126486722","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1997-12-01DOI: 10.1590/S0100-84551997000400013
L. D. Vleck
Teaching, research, and herd breeding applications may require calculation of breed additive contributions for direct and maternal genetic effects and fractions of heterozygosity associated with breed specific direct and maternal heterosis effects. These coefficients can be obtained from the first NB rows of a pseudo numerator relationship matrix where the first NB rows represent fractional contributions by breed to each animal or group representing a specific breed cross. The table begins with an NB x NB identity matrix representing pure breeds. Initial animals or representative crosses must be purebreds or two-breed crosses. Parents of initial purebreds are represented by the corresponding column and initial two-breed cross progeny by the two corresponding columns of the identity matrix. After that, usual rules are used to calculate the NB column entries corresponding to breeds for each animal. The NB entries are fractions of genes expected to be contributed by each of the pure breeds and correspond to the breed additive direct fractions. Entries in the column corresponding to the dam represent breed additive maternal fractions. Breed specific direct heterozygosity coefficients are entries of an NB x NB matrix formed by the outer product of the two NB by 1 columns associated with sire and dam of the animal. One minus sum of the diagonals represents total direct heterozygosity. Similarly, the NB x NB matrix formed by the outer product of columns associated with sire of dam and dam of dam contains breed specific maternal heterozygosity coefficients. These steps can be programmed to create covariates to merge with data. If X represents these coefficients for all unique breed crosses, then the reduced row echelon form function of MATLAB or SAS can be used on X to determine estimable functions of additive breed direct and maternal effects and breed specific direct and maternal heterosis effects
{"title":"Calculation of breed direct and maternal genetic fractions and breed specific direct and maternal heterozygosity for crossbreeding data","authors":"L. D. Vleck","doi":"10.1590/S0100-84551997000400013","DOIUrl":"https://doi.org/10.1590/S0100-84551997000400013","url":null,"abstract":"Teaching, research, and herd breeding applications may require calculation of breed additive contributions for direct and maternal genetic effects and fractions of heterozygosity associated with breed specific direct and maternal heterosis effects. These coefficients can be obtained from the first NB rows of a pseudo numerator relationship matrix where the first NB rows represent fractional contributions by breed to each animal or group representing a specific breed cross. The table begins with an NB x NB identity matrix representing pure breeds. Initial animals or representative crosses must be purebreds or two-breed crosses. Parents of initial purebreds are represented by the corresponding column and initial two-breed cross progeny by the two corresponding columns of the identity matrix. After that, usual rules are used to calculate the NB column entries corresponding to breeds for each animal. The NB entries are fractions of genes expected to be contributed by each of the pure breeds and correspond to the breed additive direct fractions. Entries in the column corresponding to the dam represent breed additive maternal fractions. Breed specific direct heterozygosity coefficients are entries of an NB x NB matrix formed by the outer product of the two NB by 1 columns associated with sire and dam of the animal. One minus sum of the diagonals represents total direct heterozygosity. Similarly, the NB x NB matrix formed by the outer product of columns associated with sire of dam and dam of dam contains breed specific maternal heterozygosity coefficients. These steps can be programmed to create covariates to merge with data. If X represents these coefficients for all unique breed crosses, then the reduced row echelon form function of MATLAB or SAS can be used on X to determine estimable functions of additive breed direct and maternal effects and breed specific direct and maternal heterosis effects","PeriodicalId":340356,"journal":{"name":"Brazilian Journal of Genetics","volume":"42 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115876398","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1997-12-01DOI: 10.1590/S0100-84551997000400007
A. M. Waldschmidt, L. A. Campos, P. Marco
Observation colonies containing only young workers from 10 matrix colonies were set up to investigate the genetic aspects involved in task division in Melipona quadrifasciata. Wide variation among origins was observed for all behaviors analyzed, but these differences were significant only for brood cell construction and propolis preparation
{"title":"Genetic variability of behaviorin Melipona quadrifasciata(Hymenoptera: Meliponinae)","authors":"A. M. Waldschmidt, L. A. Campos, P. Marco","doi":"10.1590/S0100-84551997000400007","DOIUrl":"https://doi.org/10.1590/S0100-84551997000400007","url":null,"abstract":"Observation colonies containing only young workers from 10 matrix colonies were set up to investigate the genetic aspects involved in task division in Melipona quadrifasciata. Wide variation among origins was observed for all behaviors analyzed, but these differences were significant only for brood cell construction and propolis preparation","PeriodicalId":340356,"journal":{"name":"Brazilian Journal of Genetics","volume":"125 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132491924","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1997-12-01DOI: 10.1590/S0100-84551997000400026
Í. Lopes-Cendes, H. Teive, F. Cardoso, Erika M. Viana, M. Calcagnotto, J. Costa, P. C. Trevisol-Bittencourt, J. A. Maciel, M. Rousseau, André S. Santos, A. Q. Araújo, G. Rouleau
Machado-Joseph disease (MJD) is a form of autosomal dominant spinocerebellar ataxia first described in North-American patients originating from the Portuguese islands of the Azores. Clinically this disorder is characterized by late onset progressive ataxia with associated features, such as: ophthalmoplegia, pyramidal and extrapyramidal signs and distal muscular atrophies. The causative mutation is an expansion of a CAG repeat in the coding region of the MJD1 gene. We have identified 25 unrelated families segregating the MJD mutation during a large collaborative study of spinocerebellar ataxias in Brazil. In the present study a total of 62 family members were genotyped for the CAG repeat in the MJD1 gene, as well as 63 non-MJD individuals (126 normal chromosomes), used as normal controls. We observed a wide gap between the size range of the normal and expanded CAG repeats: the normal allele had from 12 to 33 CAGs (mean = 23 CAGs), whereas the expanded alleles ranged from 66 to 78 CAGs (mean = 71.5 CAGs). There were no differences in CAG tract length according to gender of affected individuals or transmitting parent. We observed a significant negative correlation between age at onset of the disease and length of the CAG tract in the expended allele (r = -0.6, P = 0.00006); however, the size of the expanded CAG repeat could explain only about 40% of the variability in age at onset (r2 = 0.4). There was instability of the expanded CAG tract during transmission from parent to offspring, both expansions and contractions were observed; however, there was an overall tendency for expansion, with a mean increase of +2.4 CAGs. The tendency for expansion appeared to the greater in paternal (mean increase of +3.5 CAGs) than in maternal transmissions (mean increase of +1.3 CAGs). Anticipation was observed in all transmissions in which ages at onset for parent and offspring were known; however, anticipation was not always associated with an increase in the expanded CAG repeat length. Our results indicate that the molecular diagnosis of MJD can be confirmed or excluded in all suspected individuals, since alleles of intermediary size were not observed.
{"title":"Molecular characteristics of Machado-Joseph disease mutation in 25 newly described Brazilian families","authors":"Í. Lopes-Cendes, H. Teive, F. Cardoso, Erika M. Viana, M. Calcagnotto, J. Costa, P. C. Trevisol-Bittencourt, J. A. Maciel, M. Rousseau, André S. Santos, A. Q. Araújo, G. Rouleau","doi":"10.1590/S0100-84551997000400026","DOIUrl":"https://doi.org/10.1590/S0100-84551997000400026","url":null,"abstract":"Machado-Joseph disease (MJD) is a form of autosomal dominant spinocerebellar ataxia first described in North-American patients originating from the Portuguese islands of the Azores. Clinically this disorder is characterized by late onset progressive ataxia with associated features, such as: ophthalmoplegia, pyramidal and extrapyramidal signs and distal muscular atrophies. The causative mutation is an expansion of a CAG repeat in the coding region of the MJD1 gene. We have identified 25 unrelated families segregating the MJD mutation during a large collaborative study of spinocerebellar ataxias in Brazil. In the present study a total of 62 family members were genotyped for the CAG repeat in the MJD1 gene, as well as 63 non-MJD individuals (126 normal chromosomes), used as normal controls. We observed a wide gap between the size range of the normal and expanded CAG repeats: the normal allele had from 12 to 33 CAGs (mean = 23 CAGs), whereas the expanded alleles ranged from 66 to 78 CAGs (mean = 71.5 CAGs). There were no differences in CAG tract length according to gender of affected individuals or transmitting parent. We observed a significant negative correlation between age at onset of the disease and length of the CAG tract in the expended allele (r = -0.6, P = 0.00006); however, the size of the expanded CAG repeat could explain only about 40% of the variability in age at onset (r2 = 0.4). There was instability of the expanded CAG tract during transmission from parent to offspring, both expansions and contractions were observed; however, there was an overall tendency for expansion, with a mean increase of +2.4 CAGs. The tendency for expansion appeared to the greater in paternal (mean increase of +3.5 CAGs) than in maternal transmissions (mean increase of +1.3 CAGs). Anticipation was observed in all transmissions in which ages at onset for parent and offspring were known; however, anticipation was not always associated with an increase in the expanded CAG repeat length. Our results indicate that the molecular diagnosis of MJD can be confirmed or excluded in all suspected individuals, since alleles of intermediary size were not observed.","PeriodicalId":340356,"journal":{"name":"Brazilian Journal of Genetics","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132807412","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1997-12-01DOI: 10.1590/S0100-84551997000400028
R. Mingroni-Netto, R. C. Pavanello, P. Otto, A. Vianna-Morgante
We report on the cytogenetic and DNA analysis of 55 families with the fragile X (FMR-1 locus) mutation (318 individuals and 15 chorionic villi samples). A total of 129 males were investigated, 54 mentally normal and 75 presenting mental retardation. Among the 54 normal males, 11 had the premutation, and none expressed the fragile site. The full mutation was detected in 73 retarded males, and 14 (18%) presented a premutation along with the full mutation (mosaics). All of them manifested the fragile site. The frequencies of fragile site expression correlated positively with the sizes of the expansion of the CGG repeats (D). Among 153 normal females, 85 were found to be heterozygous for the premutation and 15 had the full mutation. In the premutated females the fragile site was not observed or it occurred at frequencies that did not differ from those observed in 53 noncarriers. Cytogenetic analysis was thus ineffective for the diagnosis of premutated males or females. Among the 51 heterozygotes for the full mutation, 36 (70%) had some degree of mental impairment. As in males, a positive correlation was detected between the frequencies of fragile site manifestation and the size of the expansion. However, the cytogenetic test was less effective for the detection of fully mutated females, than in the case of males, since 14% false negative results were found among females. Segregation analysis confirmed that the risk of mental retardation in the offspring of heterozygotes increases with the length of D. The average observed frequency of mental retardation in the offspring of all heterozygotes was 30%. There was no indication of meiotic drive occurring in female carriers, since the number of individuals who inherited the mutation did not differ from the number of those inheriting the normal allele. No new mutations were detected in the 55 genealogies studied here.
{"title":"Experience with molecular and cytogenetic diagnosis of fragile X syndrome in Brazilian families","authors":"R. Mingroni-Netto, R. C. Pavanello, P. Otto, A. Vianna-Morgante","doi":"10.1590/S0100-84551997000400028","DOIUrl":"https://doi.org/10.1590/S0100-84551997000400028","url":null,"abstract":"We report on the cytogenetic and DNA analysis of 55 families with the fragile X (FMR-1 locus) mutation (318 individuals and 15 chorionic villi samples). A total of 129 males were investigated, 54 mentally normal and 75 presenting mental retardation. Among the 54 normal males, 11 had the premutation, and none expressed the fragile site. The full mutation was detected in 73 retarded males, and 14 (18%) presented a premutation along with the full mutation (mosaics). All of them manifested the fragile site. The frequencies of fragile site expression correlated positively with the sizes of the expansion of the CGG repeats (D). Among 153 normal females, 85 were found to be heterozygous for the premutation and 15 had the full mutation. In the premutated females the fragile site was not observed or it occurred at frequencies that did not differ from those observed in 53 noncarriers. Cytogenetic analysis was thus ineffective for the diagnosis of premutated males or females. Among the 51 heterozygotes for the full mutation, 36 (70%) had some degree of mental impairment. As in males, a positive correlation was detected between the frequencies of fragile site manifestation and the size of the expansion. However, the cytogenetic test was less effective for the detection of fully mutated females, than in the case of males, since 14% false negative results were found among females. Segregation analysis confirmed that the risk of mental retardation in the offspring of heterozygotes increases with the length of D. The average observed frequency of mental retardation in the offspring of all heterozygotes was 30%. There was no indication of meiotic drive occurring in female carriers, since the number of individuals who inherited the mutation did not differ from the number of those inheriting the normal allele. No new mutations were detected in the 55 genealogies studied here.","PeriodicalId":340356,"journal":{"name":"Brazilian Journal of Genetics","volume":"24 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116143881","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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