The Spectrum of Mutations and Molecular Pathogenesis of Hemophilia A in 181 Portuguese Patients

Disease-causing alterations within the F8 gene were identified in 177 hemophilia A families of Portuguese origin. The spectrum of non-inversion F8 mutations in 101 families included 67 different alterations, namely: 36 missense, 8 nonsense and 4 splice site mutations, as well as 19 insertions/deletions. Thirty-four of these mutations are novel. Molecular modeling allowed prediction of the conformational changes introduced by selected amino acid substitutions and their correlation with the patients' phenotypes. The relatively frequent, population-specific, missense mutations together with de novo alterations can lead to significant differences in the spectrum of F8 mutations among different populations.

The Role of the Humoral Immune Response in the Molecular Evolution of the Envelope C2, V3 and C3 Regions in Chronically HIV-2 Infected Patients

BACKGROUND: This study was designed to investigate, for the first time, the short-term molecular evolution of the HIV-2 C2, V3 and C3 envelope regions and its association with the immune response. Clonal sequences of the env C2V3C3 region were obtained from a cohort of eighteen HIV-2 chronically infected patients followed prospectively during 2-4 years. Genetic diversity, divergence, positive selection and glycosylation in the C2V3C3 region were analysed as a function of the number of CD4+ T cells and the anti-C2V3C3 IgG and IgA antibody reactivity RESULTS: The mean intra-host nucleotide diversity was 2.1% (SD, 1.1%), increasing along the course of infection in most patients. Diversity at the amino acid level was significantly lower for the V3 region and higher for the C2 region. The average divergence rate was 0.014 substitutions/site/year, which is similar to that reported in chronic HIV-1 infection. The number and position of positively selected sites was highly variable, except for codons 267 and 270 in C2 that were under strong and persistent positive selection in most patients. N-glycosylation sites located in C2 and V3 were conserved in all patients along the course of infection. Intra-host variation of C2V3C3-specific IgG response over time was inversely associated with the variation in nucleotide and amino acid diversity of the C2V3C3 region. Variation of the C2V3C3-specific IgA response was inversely associated with variation in the number of N-glycosylation sites. CONCLUSION: The evolutionary dynamics of HIV-2 envelope during chronic aviremic infection is similar to HIV-1 implying that the virus should be actively replicating in cellular compartments. Convergent evolution of N-glycosylation in C2 and V3, and the limited diversification of V3, indicates that there are important functional constraints to the potential diversity of the HIV-2 envelope. C2V3C3-specific IgG antibodies are effective at reducing viral population size limiting the number of virus escape mutants. The C3 region seems to be a target for IgA antibodies and increasing N-linked glycosylation may prevent HIV-2 envelope recognition by these antibodies. Our results provide new insights into the biology of HIV-2 and its relation with the human host and may have important implications for vaccine design.

Métodos Preditivos de Metastização Ganglionar Adicional em Cancro da Mama com Gânglio Sentinela Positivo

Objectivos As recomendações para a realização de linfadenectomia axilar nos doentes com cancro da mama em estádio precoce e sujeitas a biópsia de gânglio sentinela com presença de macrometástase foram recentemente actualizadas, baseadas nos últimos estudos publicados (Z0011 e IBCSG 23-01). Mantém-se, no entanto, alguma controvérsia na decisão de não realização de cirurgia radical axilar nos doentes com gânglio sentinela positivo. Têm sido desenvolvidos métodos preditivos de metastização ganglionar adicional. Um dos mais conhecidos, desenvolvido no Memorial Sloan-Kettering Cancer Center (MSKCC), recorre a variáveis do tumor e características do gânglio sentinela. Mais recentemente com a utilização de métodos moleculares (como o One Step Nucleic Acid - OSNA) para estudo do gânglio sentinela tem sido avaliada a capacidade preditiva da quantidade total de cópias mRNA da citoqueratina 19. Pretende-se estudar na nossa amostra a capacidade preditiva do nomograma do MSKCC e da carga tumoral total. Propõe-se ainda avaliar o número de macrometástases encontradas na biópsia de gânglio sentinela e sua relação na metastização ganglionar adicional. Material e métodos Avaliação retrospectiva de 819 doentes com cancro da mama (Tis – T2) submetidos a biópsia de gânglio sentinela no Centro Hospitalar de Lisboa Central durante o período de 1 de Janeiro de 2005 e 31 de Dezembro de 2013. Foram identificados 123 doentes com gânglio sentinela positivo que realizaram linfadenectomia axilar imediata. A análise do gânglio sentinela foi executada por métodos histológicos em 78 doentes e por método molecular (OSNA) em 45 doentes. Os dois grupos foram estudados separadamente, tendo sido no primeiro aplicado o nomograma do MSKCC e no segundo obtida a carga tumoral total. Utilizou-se o modelo de regressão logística para analisar o poder preditivo e discriminativo destes dois métodos. Adicionalmente, para avaliar a potencial importância do número de macrometástases na metastização ganglionar adicional, foi ajustado um novo modelo de regressão logística considerando esta variável e a carga tumoral total. Ambos os métodos foram também avaliados através da área sob a curva ROC (AUC) e do teste de Hosmer-Lemeshow, respectivamente. O nível de significância adoptado foi α = 0.05. O estudo estatístico foi realizado com recurso ao SPSS. Resultados No grupo em que foi aplicado o nomograma do MSKCC obteve-se uma AUC=0.67 (I.C. 95% = 0.55 – 0.79), e no grupo em que foi avaliada a carga tumoral total uma AUC=0.78 (I.C. 95% = 0.64 – 0.91). Os poderes preditivos de ambos foram, respectivamente, p=0.15 e p=0.46. Constatou-se que o desempenho do modelo resultante da junção da carga tumoral total com o número de macrometástases encontradas no estudo do gânglio sentinela foi bastante satisfatório (AUC=0.87, I.C 95% = 0.76 – 0.98, poder preditivo p=0.33). Conclusão Foi validado externamente o modelo do MSKCC para a amostra em estudo, apresentando uma menor acuidade discriminativa em relação ao estudo original (AUC=0.67 versus AUC=0.75). Por outro lado, após verificação da homogeneidade de ambos os grupos no que diz respeito a todas as variáveis de interesse, conclui-se que a carga tumoral total aparenta uma maior acuidade preditiva e discriminativa na metastização ganglionar adicional que o nomograma do MSKCC. Quando desenvolvido um modelo agregando a carga tumoral total avaliada por OSNA e o número de macrometástases no gânglio sentinela, obteve-se uma capacidade discriminativa ainda superior. A carga tumoral total avaliada por OSNA, ou esta incluída num modelo conjunto com o número de macrometástases obtidas no estudo do gânglio sentinela, poderão representar importantes ferramentas preditivas. Serão no entanto necessários estudos adicionais com amostras superiores para consolidar estes resultados. Bibliografia 1. 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Multicenter validation of two nomograms to predict non-sentinel node involvement in breast cancer. Clin Transl Oncol. Fevereiro de 2013;15(2):117–23. 5. Banerjee SM, Michalopoulos NV, Williams NR, Davidson T, El Sheikh S, McDermott N, et al. Detailed evaluation of one step nucleic acid (OSNA) molecular assay for intra-operative diagnosis of sentinel lymph node metastasis and prediction of non-sentinel nodal involvement: experience from a London teaching hospital. Breast. Agosto de 2014;23(4):378–84. 6. Peg V, Espinosa-Bravo M, Vieites B, Vilardell F, Antúnez JR, de Salas MS, et al. Intraoperative molecular analysis of total tumor load in sentinel lymph node: a new predictor of axillary status in early breast cancer patients. Breast Cancer Res Treat. Maio de 2013;139(1):87–93. 7. Tiernan JP, Verghese ET, Nair A, Pathak S, Kim B, White J, et al. Systematic review and meta-analysis of cytokeratin 19-based one-step nucleic acid amplification versus histopathology for sentinel lymph node assessment in breast cancer. Br J Surg. Março de 2014;101(4):298–306. 8. Heilmann T, Mathiak M, Hofmann J, Mundhenke C, van Mackelenbergh M, Alkatout I, et al. Intra-operative use of one-step nucleic acid amplification (OSNA) for detection of the tumor load of sentinel lymph nodes in breast cancer patients. J Cancer Res Clin Oncol. Outubro de 2013;139(10):1649–55. 9. Chaudhry A, Williams S, Cook J, Jenkins M, Sohail M, Calder C, et al. The real-time intra-operative evaluation of sentinel lymph nodes in breast cancer patients using One Step Nucleic Acid Amplification (OSNA) and implications for clinical decision-making. Eur J Surg Oncol. Fevereiro de 2014;40(2):150–7.

Calcinose Cutis, Insuficiência Renal e Heparinas de Baixo Peso Molecular Contendo Cálcio

Foi solicitada observação por Dermatologia de uma doente de 35 anos de idade, de raça negra, por 2 nódulos subcutâneos localizados na região paraumbilical direita e flanco direito com 2 semanas de evolução. Da história prévia, destaque para doença renal crónica em programa de hemodiálise e infeção pelo vírus da imunodeficiência humana (VIH-1). Ao exame objetivo observaram-se 2 nódulos bem delimitados, subcutâneos, sem alteração da coloração; à palpação, estes eram dolorosos, de consistência pétrea e não aderentes aos planos profundos. Foi realizada biópsia incisional para exame histopatológico, que confirmou a hipótese diagnóstica de calcinose cutis. Uma revisão cuidadosa de toda a medicação realizada permitiu estabelecer a relação entre este achado e a administração subcutânea de nadroparina cálcica nessa localização, umas semanas antes. A dermatose regrediu espontaneamente em 2 meses após a suspensão das injeções subcutâneas de nadroparina cálcica. A calcinose cutis devida à administração de heparinas de baixo peso molecular contendo cálcio é rara, admitindo-se que elevação do produto fósforo-cálcio possa ser determinante na sua fisiopatologia. É geralmente autolimitada, resolvendo espontaneamente.

Leber Congenital Amaurosis: Comprehensive Survey of the Genetic Heterogeneity, Refinement of the Clinical Definition, and Genotype-Phenotype Correlations as a Strategy for Molecular Diagnosis

Leber congenital amaurosis (LCA) is the earliest and most severe form of all inherited retinal dystrophies, responsible for congenital blindness. Disease-associated mutations have been hitherto reported in seven genes. These genes are all expressed preferentially in the photoreceptor cells or the retinal pigment epithelium but they are involved in strikingly different physiologic pathways resulting in an unforeseeable physiopathologic variety. This wide genetic and physiologic heterogeneity that could largely increase in the coming years, hinders the molecular diagnosis in LCA patients. The genotyping is, however, required to establish genetically defined subgroups of patients ready for therapy. Here, we report a comprehensive mutational analysis of the all known genes in 179 unrelated LCA patients, including 52 familial and 127 sporadic (27/127 consanguineous) cases. Mutations were identified in 47.5% patients. GUCY2D appeared to account for most LCA cases of our series (21.2%), followed by CRB1 (10%), RPE65 (6.1%), RPGRIP1 (4.5%), AIPL1 (3.4%), TULP1 (1.7%), and CRX (0.6%). The clinical history of all patients with mutations was carefully revisited to search for phenotype variations. Sound genotype-phenotype correlations were found that allowed us to divide patients into two main groups. The first one includes patients whose symptoms fit the traditional definition of LCA, i.e., congenital or very early cone-rod dystrophy, while the second group gathers patients affected with severe yet progressive rod-cone dystrophy. Besides, objective ophthalmologic data allowed us to subdivide each group into two subtypes. Based on these findings, we have drawn decisional flowcharts directing the molecular analysis of LCA genes in a given case. These flowcharts will hopefully lighten the heavy task of genotyping new patients but only if one has access to the most precise clinical history since birth.

Clinical and Molecular Characterization of Diastrophic Dysplasia in the Portuguese Population

SLC26A2-related dysplasias encompass a spectrum of diseases: from lethal achondrogenesis type 1B (ACG1B; MIM #600972) and atelosteogenesis type 2 (AO2; MIM #256050) to classical diastrophic dysplasia (cDTD; MIM #222600) and recessive multiple epiphyseal dysplasia (rMED; MIM #226900). This study aimed at characterizing clinically, radiologically and molecularly 14 patients affected by non-lethal SLC26A2-related dysplasias and at evaluating genotype-phenotype correlation. Phenotypically, eight patients were classified as cDTD, four patients as rMED and two patients had an intermediate phenotype (mild DTD - mDTD, previously 'DTD variant'). The Arg279Trp mutation was present in all patients, either in homozygosity (resulting in rMED) or in compound heterozygosity with the known severe alleles Arg178Ter or Asn425Asp (resulting in DTD) or with the mutation c.727-1G>C (causing mDTD). The 'Finnish mutation', c.-26+2T>C, and the p.Cys653Ser, both frequent mutations in non-Portuguese populations, were not identified in any of the patients of our cohort and are probably very rare in the Portuguese population. A targeted mutation analysis for p.Arg279Trp and p.Arg178Ter in the Portuguese population allows the identification of approximately 90% of the pathogenic alleles.