Aloir Queiroz de Araújo

Screening of MYH7, MYBPC3, and TNNT2 genes in Brazilian patients with hypertrophic cardiomyopathy

BACKGROUND Hypertrophic cardiomyopathy (HC) is the most prevalent genetic cardiac disease caused by a mutation in sarcomeres, Z-disks, or calcium-handling genes and is characterized by unexplained left ventricular hypertrophy. The aim of this study was to determine the genetic profile of Brazilian patients with HC and correlate the genotype with the phenotype. METHODS We included 268 index patients from São Paulo city and 3 other cities in Brazil and extracted their DNA from whole blood. We amplified the coding sequencing of MYH7, MYBPC3, and TNNT2 genes and sequenced them with an automatic sequencer. RESULTS We identified causal mutations in 131 patients (48.8%). Seventy-eight (59.5%) were in the MYH7 gene, 50 (38.2%) in the MYBPC3 gene, and 3 (2.3%) in the TNNT2 gene. We identified 69 mutations, 24 not previously described. Patients with an identified mutation were younger at diagnosis and at current age, had a higher mean heart rate and higher nonsustained ventricular tachycardia frequency compared with those without a mutation. Patients with MYH7 gene mutations had a larger left atrium and higher frequency of atrial fibrillation than did patients with MYBPC3 gene mutations. CONCLUSION The presence of a mutation in one of the genes suggests a worse prognosis. Mutations in the MYH7 gene, rather than in the MYBPC3 gene, were also related to a worse prognosis. This is the first work characterizing HC molecular epidemiology in the Brazilian population for the 3 most important genes.

[Study of mutations causing hypertrophic cardiomyopathy in a group of patients from Espirito Santo, Brazil].

FUNDAMENTO: La cardiomiopatia hipertrofica (CH) es la enfermedad cardiaca hereditaria mas frecuente, causada por mutaciones en los genes codificadores para proteinas del sarcomero. Aunque se hayan identificado mas de 430 mutaciones en varios continentes y paises, no hay relato de que esto se haya estudiado en Brasil. OBJETIVO: Conducir un estudio genetico para identificar mutaciones geneticas que causan la CH en un grupo de pacientes en el estado de Espirito Santo, Brasil. METODOS: Usando la tecnica SSCP, se estudiaron 12 exones de los tres principales genes involucrados con la CH: exones 15, 20, 21, 22 y 23 del gen de la cadena pesada de la β-miosina (MYH7), exones 7, 16, 18, 22 y 24 del gen de la proteina C unida a la miosina (MYBPC3) y exones 8 y 9 del gen de la troponina T (TNNT2). RESULTADOS: Se encontraron 16 alteraciones, incluyendo dos mutaciones, una de ellas posiblemente patogenica en el gen MYBPC3 gen (p. Glu441Lys) y otra patogenica ya descrita en el gen TNNT2 (p. Arg92Trp); 8 variaciones de secuencia raras y 6 variaciones de secuencia con frecuencia alelica mayor que el 1% (polimorfismos). CONCLUSIONES: Con estos datos, es posible concluir que el genotipaje de los pacientes es factible en nuestro medio. Es posible que la variante p.Glu441Lys en el exon 16 del gen MYBPC3 sea patogenica, resultando en un fenotipo mas leve que el encontrado en asociacion con otras mutaciones. La variante p.Arg92Trp en el exon 9 del gen TNNT2 no resulta en un fenotipo tan homogeneo como el descrito anteriormente y puede llevar a hipertrofia grave.BACKGROUND Hypertrophic cardiomyopathy (HC) is the most frequent cardiac hereditary disease, caused by mutations in sarcomere protein coding genes. Although more than 430 mutations have been identified in several continents and countries, there have been no reports of mutations in Brazil. OBJECTIVE To carry out a genetic study to identify genetic mutations that cause HC in a group of patients in Espirito Santo, Brazil. METHODS Using the SSCP technique, 12 exons from the three main genes involved in HC were studied: exons 15, 20, 21, 22 and 23 of the beta-myosin heavy chain gene (MYH7), exons 7, 16, 18, 22 and 24 of the myosin binding protein C gene (MYBPC3) and exons 8 and 9 of troponin T gene (TNNT2). RESULTS 16 alterations were found, including two mutations, one of them possibly pathogenic in the MYBPC3 gene (p. Glu441Lys) and another pathogenic one, previously described in the TNNT2 gene (p.Arg92Trp), 8 rare sequence variations and 6 sequence variations with allelic frequency higher than 1% (polymorphisms). CONCLUSION These data allow the conclusion that the genotyping of patients is feasible in our country. It is possible that the isolated p.Glu441Lys variant identified in exon 16 of the MYBPC3 gene is pathogenic, promoting a milder phenotype than that found when in association with other mutations. The p.Arg92Trp variant in the exon 9 of TNNT2 gene does not promote such a homogeneous phenotype as previously described and it can lead to severe hypertrophy.

Estudo de mutações causadoras de cardiomiopatia hipertrófica em um grupo de pacientes no Espírito Santo, Brasil

FUNDAMENTO: La cardiomiopatia hipertrofica (CH) es la enfermedad cardiaca hereditaria mas frecuente, causada por mutaciones en los genes codificadores para proteinas del sarcomero. Aunque se hayan identificado mas de 430 mutaciones en varios continentes y paises, no hay relato de que esto se haya estudiado en Brasil. OBJETIVO: Conducir un estudio genetico para identificar mutaciones geneticas que causan la CH en un grupo de pacientes en el estado de Espirito Santo, Brasil. METODOS: Usando la tecnica SSCP, se estudiaron 12 exones de los tres principales genes involucrados con la CH: exones 15, 20, 21, 22 y 23 del gen de la cadena pesada de la β-miosina (MYH7), exones 7, 16, 18, 22 y 24 del gen de la proteina C unida a la miosina (MYBPC3) y exones 8 y 9 del gen de la troponina T (TNNT2). RESULTADOS: Se encontraron 16 alteraciones, incluyendo dos mutaciones, una de ellas posiblemente patogenica en el gen MYBPC3 gen (p. Glu441Lys) y otra patogenica ya descrita en el gen TNNT2 (p. Arg92Trp); 8 variaciones de secuencia raras y 6 variaciones de secuencia con frecuencia alelica mayor que el 1% (polimorfismos). CONCLUSIONES: Con estos datos, es posible concluir que el genotipaje de los pacientes es factible en nuestro medio. Es posible que la variante p.Glu441Lys en el exon 16 del gen MYBPC3 sea patogenica, resultando en un fenotipo mas leve que el encontrado en asociacion con otras mutaciones. La variante p.Arg92Trp en el exon 9 del gen TNNT2 no resulta en un fenotipo tan homogeneo como el descrito anteriormente y puede llevar a hipertrofia grave.BACKGROUND Hypertrophic cardiomyopathy (HC) is the most frequent cardiac hereditary disease, caused by mutations in sarcomere protein coding genes. Although more than 430 mutations have been identified in several continents and countries, there have been no reports of mutations in Brazil. OBJECTIVE To carry out a genetic study to identify genetic mutations that cause HC in a group of patients in Espirito Santo, Brazil. METHODS Using the SSCP technique, 12 exons from the three main genes involved in HC were studied: exons 15, 20, 21, 22 and 23 of the beta-myosin heavy chain gene (MYH7), exons 7, 16, 18, 22 and 24 of the myosin binding protein C gene (MYBPC3) and exons 8 and 9 of troponin T gene (TNNT2). RESULTS 16 alterations were found, including two mutations, one of them possibly pathogenic in the MYBPC3 gene (p. Glu441Lys) and another pathogenic one, previously described in the TNNT2 gene (p.Arg92Trp), 8 rare sequence variations and 6 sequence variations with allelic frequency higher than 1% (polymorphisms). CONCLUSION These data allow the conclusion that the genotyping of patients is feasible in our country. It is possible that the isolated p.Glu441Lys variant identified in exon 16 of the MYBPC3 gene is pathogenic, promoting a milder phenotype than that found when in association with other mutations. The p.Arg92Trp variant in the exon 9 of TNNT2 gene does not promote such a homogeneous phenotype as previously described and it can lead to severe hypertrophy.

Clinical predictors of a positive genetic test in hypertrophic cardiomyopathy in the Brazilian population

BackgroundHypertrophic cardiomyopathy is a genetic autosomal dominant disease characterized by left ventricular hypertrophy. The molecular diagnosis is important but still expensive. This work aimed to find clinical predictors of a positive genetic test in a Brazilian tertiary centre cohort of index cases with HCM.MethodsIn the study were included patients with HCM clinical diagnosis. For genotype x phenotype comparison we have evaluated echocardiographic, electrocardiographic, and nuclear magnetic resonance measures. All patients answered a questionnaire about familial history of HCM and/or sudden death. β-myosin heavy chain, myosin binding protein C, and troponin T genes were sequenced for genetic diagnosis.ResultsThe variables related to a higher probability of a positive genetic test were familial history of HCM, higher mean heart frequency, presence of NSVT and lower age. Probabilities of having a positive molecular genetic test were calculated from the final multivariate logistic regression model and were used to identify those with a higher probability of a positive molecular diagnosis.ConclusionsWe developed an easy and fast screening method that takes into account only clinical data that can help to select the patients with a high probability of positive genetic results from molecular sequencing of Brazilian HCM patients.

Estudio de mutaciones causadoras de cardiomiopatía hipertrófica en un grupo de pacientes en Espírito Santo, Brasil

FUNDAMENTO: La cardiomiopatia hipertrofica (CH) es la enfermedad cardiaca hereditaria mas frecuente, causada por mutaciones en los genes codificadores para proteinas del sarcomero. Aunque se hayan identificado mas de 430 mutaciones en varios continentes y paises, no hay relato de que esto se haya estudiado en Brasil. OBJETIVO: Conducir un estudio genetico para identificar mutaciones geneticas que causan la CH en un grupo de pacientes en el estado de Espirito Santo, Brasil. METODOS: Usando la tecnica SSCP, se estudiaron 12 exones de los tres principales genes involucrados con la CH: exones 15, 20, 21, 22 y 23 del gen de la cadena pesada de la β-miosina (MYH7), exones 7, 16, 18, 22 y 24 del gen de la proteina C unida a la miosina (MYBPC3) y exones 8 y 9 del gen de la troponina T (TNNT2). RESULTADOS: Se encontraron 16 alteraciones, incluyendo dos mutaciones, una de ellas posiblemente patogenica en el gen MYBPC3 gen (p. Glu441Lys) y otra patogenica ya descrita en el gen TNNT2 (p. Arg92Trp); 8 variaciones de secuencia raras y 6 variaciones de secuencia con frecuencia alelica mayor que el 1% (polimorfismos). CONCLUSIONES: Con estos datos, es posible concluir que el genotipaje de los pacientes es factible en nuestro medio. Es posible que la variante p.Glu441Lys en el exon 16 del gen MYBPC3 sea patogenica, resultando en un fenotipo mas leve que el encontrado en asociacion con otras mutaciones. La variante p.Arg92Trp en el exon 9 del gen TNNT2 no resulta en un fenotipo tan homogeneo como el descrito anteriormente y puede llevar a hipertrofia grave.BACKGROUND Hypertrophic cardiomyopathy (HC) is the most frequent cardiac hereditary disease, caused by mutations in sarcomere protein coding genes. Although more than 430 mutations have been identified in several continents and countries, there have been no reports of mutations in Brazil. OBJECTIVE To carry out a genetic study to identify genetic mutations that cause HC in a group of patients in Espirito Santo, Brazil. METHODS Using the SSCP technique, 12 exons from the three main genes involved in HC were studied: exons 15, 20, 21, 22 and 23 of the beta-myosin heavy chain gene (MYH7), exons 7, 16, 18, 22 and 24 of the myosin binding protein C gene (MYBPC3) and exons 8 and 9 of troponin T gene (TNNT2). RESULTS 16 alterations were found, including two mutations, one of them possibly pathogenic in the MYBPC3 gene (p. Glu441Lys) and another pathogenic one, previously described in the TNNT2 gene (p.Arg92Trp), 8 rare sequence variations and 6 sequence variations with allelic frequency higher than 1% (polymorphisms). CONCLUSION These data allow the conclusion that the genotyping of patients is feasible in our country. It is possible that the isolated p.Glu441Lys variant identified in exon 16 of the MYBPC3 gene is pathogenic, promoting a milder phenotype than that found when in association with other mutations. The p.Arg92Trp variant in the exon 9 of TNNT2 gene does not promote such a homogeneous phenotype as previously described and it can lead to severe hypertrophy.

Hypertrophic cardiomyopathy in monozygotic twins.

Male monozygotic twins (MT), age 19 years, with obstructive hypertrophic cardiomyopathy (HCM), symptoms (exertional dyspnea) started around age 13 years, and similar clinical presentation (a grade 3/6 systolic murmur heard in the left lower sternal border, typical ECG signs of left ventricular hypertrophy). In both patients, there were echocardiographic moderate left atrial enlargement, massive septal hypertrophy (>30mm) and severe resting outflow tract gradient, without significant differences betweem them. Some discordances were observed in two-dimensional images (Figure 1). Color Doppler showed marked septal coronary branchs in twin G (Figure 2), which was not found in twin V. Twin G evoluted to medical refractory NYHA III/IV functional class and was referred to a surgical myectomy. Hypertrophic cardiomyopathy is a primary disease of the myocardium caused by mutations in genes coding for sarcomeric proteins 1 , and the phenotype can be influenced by modifiers genes 2