Associação incomum entre fenótipo e genótipo em dois pacientes com câncer hematológico / Unusual association between phenotype and genotype in two patients with hematological cancer

Descrição: Relato de caso de um paciente com um transcrito raro (e1a2) na Leucemia Mieloide Crônica (LMC) e outro com uma translocação rara na Síndrome Mielodisplásica (SMD). Discussão: O transcrito e1a2 possui frequência de 1% entre os casos de LMC, já a translocação t(11,17)(q23;q21) não foi evidenciada em paciente com SMD do tipo Anemia Refratária com Excesso de Blastos (AREB) do tipo 2. Conclusão: Ambos os casos apresentados possuem associação incomum entre fenótipo e genótipo. A correlação da clínica com os achados laboratoriais é importante para a determinação fidedigna do diagnóstico e prognóstico destes pacientes.

Description: Case report of a patient with a rare transcript (e1a2) in Chronic Myeloid Leukemia (CML) and another with a rare translocation in Myelodysplastic Syndrome (SMD). Discussion: The transcript e1a2 has a frequency of 1% in CML cases, whereas t (11,17) (q23; q21) translocation was not observed in a patient with type of Refractory Anemia with Excess Blasts (AREB) type 2. Conclusion: Both cases reported have unusual association between phenotype and genotype. The correlation of the clinic with the laboratory findings is important for the reliable determination of the diagnosis and prognosis of these patients.

Analysis of the qPCR Assay Efficacy as Molecular Diagnostic in Patients with Chemotherapy and/or Antibiotic Therapy

Abstract High sensitivity of qPCR assay can be compromised by the presence of PCR inhibitors in samples analyzed. The aim of this study was to analyze the RT-qPCR assay efficiency considering the RNA quality/quantity and the presence of PCR inhibitors in patients with chemotherapy and/or antibiotic therapy. We analyzed 60 samples using RT-qPCR from individuals suspected of leukemia and 44 samples were quantified by fluorimetry and spectrophotometry. The efficiency of the RT-qPCR assay was evaluated comparing the threshold cycle (Ct) from tested samples and the standard curve. The 260/280 and 260/230 ratios, the presence of PCR inhibitors and the amount of sample (ng) used in the RT-qPCR reaction can be associated with 56.8% (R²=0.56, p<0.05) in the Ct obtained. The decrease of the RT-qPCR efficiency can be explained in 42,8% due to the variation of the 260/280 ratio (R²=0.42,p<0.05). The presence of antibiotics in the blood sample can be associated in 11.3% with the variability of 260/280 ratio (R²=0.11,p<0.05). Presence of chemotherapeutic drugs in the blood sample was not correlated with Ct variation (p=0.17). The spectrophotometer determines a RNA quantification with 2.2 times higher than the fluorimeter (t=2.2, p=0,03) and this difference is correlated with the 260/280 ratio (R²=0.36, p<0.05). Samples with low purity had a reduction in the qPCR efficiency, although we did not observe false results.

Investigation of intermediate CAG alleles of the HTT in the general population of Rio de Janeiro, Brazil, in comparison with a sample of Huntington disease-affected families.

BACKGROUND: Huntington disease (HD) (MIM: 143100) is a severe autosomal dominant neurodegenerative disease caused by the expansion of CAG trinucleotides (>35) in the HTT. OBJECTIVE: To investigate the frequency of intermediate CAG alleles (IAs) in individuals residing in Rio de Janeiro city with no familial history of HD (general population, GP) in comparison with a sample of individuals from families presenting with HD who were previously investigated by our group (affected sample, AS). RESULTS: The frequency of normal CAG alleles was 96.2%, while that of IAs was 3.6%, and that of reduced penetrance alleles was 0.2% in the GP (n = 470 chromosomes); 7.2% (17/235 individuals) of the GP presented an IA in heterozygosis with a normal allele. There was no statistically significant difference between the frequencies of the IAs in the GP and in the AS (p = .9). The most frequent haplotype per normal allele was (CAG)17-(CCG)7 (101/461) and per IA was (CAG)27-(CCG)7 (6/17) in the GP. These haplotypes were also the most frequent in the normal and IA chromosomes of the AS, respectively. CONCLUSION: The genetic profiles of the IAs obtained from GP and AS were rather similar. It is important to investigate the frequencies of the IAs because expansions arise from a step-by-step mechanism in which, during intergenerational transmission, large normal alleles can generate IAs, which are then responsible for generating de novo HD mutations. The genetic investigation of IAs in the GP was also important because it was focused on the population of Rio de Janeiro, an understudied group. CCG7 was the most frequent CCG allele in linkage disequilibrium with normal, intermediate, and expanded CAG alleles, similar to the Western Europe population. However, a more robust investigation, in conjunction with haplogroup determination (A, B, or C), will be required to elucidate the ancestral origin of the HTT mutations in Brazilians.

A Comprehensive Haplotype-Targeting Strategy for Allele-Specific HTT Suppression in Huntington Disease.

Huntington disease (HD) is a fatal neurodegenerative disorder caused by a gain-of-function mutation in HTT. Suppression of mutant HTT has emerged as a leading therapeutic strategy for HD, with allele-selective approaches targeting HTT SNPs now in clinical trials. Haplotypes associated with the HD mutation (A1, A2, A3a) represent panels of allele-specific gene silencing targets for efficient treatment of individuals with HD of Northern European and indigenous South American ancestry. Here we extend comprehensive haplotype analysis of the HD mutation to key populations of Southern European, South Asian, Middle Eastern, and admixed African ancestry. In each of these populations, the HD mutation occurs predominantly on the A2 HTT haplotype. Analysis of HD haplotypes across all affected population groups enables rational selection of candidate target SNPs for development of allele-selective gene silencing therapeutics worldwide. Targeting SNPs on the A1 and A2 haplotypes in parallel is essential to achieve treatment of the most HD-affected subjects in populations where HD is most prevalent. Current allele-specific approaches will leave a majority of individuals with HD untreated in populations where the HD mutation occurs most frequently on the A2 haplotype. We further demonstrate preclinical development of potent and selective ASOs targeting SNPs on the A2 HTT haplotype, representing an allele-specific treatment strategy for these individuals. On the basis of comprehensive haplotype analysis, we show the maximum proportion of HD-affected subjects that may be treated with three or four allele targets in different populations worldwide, informing current allele-specific HTT silencing strategies.

Avaliação funcional em indivíduos com doença de Huntington: uma série de casos / Functional evaluation in Huntington's disease: a series of cases

A doença de Huntington (DH) é uma desordem neurodegenerativa, que cursa com distúrbios motores, cognitivos e comportamentais que contribuem para o comprometimento da funcionalidade. Este estudo investigou o grau de funcionalidade e acometimento de indivíduos portadores da DH, com o Índice de Barthel Modificado (IBM) e por meio do Disease Burden Score (DBS). As variáveis analisadas de cada indivíduo foram: a idade atual, o gênero, a idade de início da doença e o número das repetições CAG (gene HTT). Seis indivíduos foram avaliados, três do sexo masculino 63,6 anos (±10,9) e três do sexo feminino 58,3 anos (±14,2) com o diagnóstico genético positivo para DH provenientes do município de Ervália/MG. O sexo feminino apresentou a idade de início menor comparado ao sexo masculino, com média de 38,3 anos (±8,9) e 46,6 anos (±7,6), respectivamente. O valor médio do número de repetições CAG no sexo feminino foi de 46,3 (±4,1) e no sexo masculino, 42,33 (±1,5). O grau de desempenho funcional determinado pelo IBM foi de 9,3 (±1,1) para o sexo feminino, com dependência total, e para o sexo masculino, 36 (±4,3), com dependência severa. O valor médio obtido pelo DBS no sexo feminino foi de 596,8 (±101,9), com maior grau de acometimento da doença comparado ao sexo masculino com 425,1 (±39,2). O grupo de mulheres com DH apresentou início dos sintomas mais cedo com maior número de expansões CAG quando comparado ao grupo masculino. Todos os pacientes apresentaram dependência total em relação à execução das atividades de vida diária. Sugere-se que pesquisas futuras sejam realizadas com maior número de indivíduos afetados pela DH para que os resultados observados sejam confirmados.

Huntington's disease (HD) is a neurodegenerative disorder, presenting with motor, cognitive and behavioral impairments that contribute to the decrease of the functional performance. This study investigated the degree of functionality and impairment of individuals with HD using the Modified Barthel Index (MBI) and the Disease Burden Score (DBS). The following variables were investigated : the age of onset, the gender, the current age and the number of CAG (HTT gene) repeats. Six HD patients from the municipality of Ervália-MG, three males 63.6 years old (±10.9) and three females 58.3 years old (±14.2), who had a positive genetic diagnosis for HD, were investigated. The female group had the lowest age of onset with an average of 38.3 years (±8.9), compared to the male group, with 46.6 years (±7.6). The mean of the number of CAG repeats in the female gender was 46.3 (±4.1) and in the male, 42.33 (±1.5). The degree of functional performance assessed by IBM was 9.3 (±1.1) for the female group, with total dependence, and for the male group, 36 (±4.3), with severe dependence. The mean of DBS value in the female group was 596.8 (±101.9) with a higher degree of disease involvement compared to the male group 425.1 (±39.2). The group of women with HD showed earlier onset of symptoms with a greater number of CAG repeats when compared to the male group. All patients presented total dependence on daily living activities. We strongly suggest further research involving a larger group of individuals affected by HD for statistical validation.

A Study of a Geographical Cluster of Huntington's Disease in a Brazilian Town of Zona da Mata, Minas Gerais State.

BACKGROUND/AIMS: Our aim was to investigate a geographical cluster of Huntington's disease (HD) in Ervalia, a Brazilian town of Minas Gerais state (MG). Therefore, we calculated the minimum prevalence of HD in Ervalia, known to have many HD affected families. We also determined the genetic profile of the polymorphic CAG region of the HTT gene in 32 subjects of these affected families. METHODS: A descriptive cross-sectional study was performed, starting in January 2011 until June 2013. Individuals who participated in the survey were all from Ervalia town, MG. RESULTS: The minimum prevalence rate found was 7.2/10,000 people, higher than the worldwide prevalence. CONCLUSION: The minimum prevalence of HD in Ervalia was at least 10.3- to 14.4-fold greater than that of the world population, although it does not represent the overall prevalence of the disease in Brazil. Certainly an expanded survey in the country will lead to a lower prevalence estimate than Ervalia's.