RESUMO
BACKGROUND: Mutations in the erythroid-specific 5-aminolevulinate-synthase gene (ALAS2) have been identified in many cases of X-linked sideroblastic anemia (XLSA). METHODS: A polymerase chain reaction-mediated restriction fragment length polymorphism (RFLP) assay was used. RESULTS: A G527T point mutation was identified. This resulted in a substitution of tyrosine for asparagine at residue 159 (D159Y). This mutation was also identified in the mother of the two probands. Mutations in all three individuals were confirmed by DNA sequencing analysis. CONCLUSIONS: We identified a missense mutation in exon 5 of the ALAS2 gene in two brothers of a consanguineous marriage, who were clinically pyridoxine-responsive.
Assuntos
5-Aminolevulinato Sintetase/genética , Anemia Sideroblástica/enzimologia , Anemia Sideroblástica/genética , Éxons/genética , Ligação Genética/genética , Mutação de Sentido Incorreto/genética , Cromossomo X/genética , Anemia Sideroblástica/patologia , Sequência de Bases , Pré-Escolar , Consanguinidade , Análise Mutacional de DNA , Eritrócitos/patologia , Feminino , Humanos , Isoenzimas/genética , Masculino , Dados de Sequência Molecular , Polimorfismo de Fragmento de RestriçãoRESUMO
Definitive diagnosis of B-cell non-Hodgkin lymphomas often requires demonstration of B-cell monoclonality. Immunohistochemical detection of monotypic immunoglobulin light chain expression, and thereby B-cell monoclonality, may be accomplished readily using fresh cell suspensions or frozen tissue sections. However, immunohistochemical detection of immunoglobulin light chain expression in formalin-fixed, paraffin-embedded tissues is more difficult; with few exceptions, techniques suitable for formalin-fixed, paraffin-embedded tissues are not widely available. This report describes and validates a method for detecting immunoglobulin light chain expression in formalin-fixed, paraffin-embedded tissues using a heat-induced epitope retrieval technique. This method was evaluated in a series of 113 cases of B-cell non-Hodgkin lymphoma, including 73 cases with correlative flow cytometric immunophenotyping data. Monotypic light chain expression was demonstrated in 91 (81%) of 113 cases, including several small core biopsy specimens with extremely limited tissue. Compared with the reference method (flow cytometric immunophenotyping), the specificity of the assay was 100%. Interobserver reproducibility was excellent, with 87% concordance between two independent observers categorizing cases as indeterminate, suggestive or diagnostic of kappa or lambda light chain restriction (Cohen kappa statistic: 0.81). In summary, the described method permits demonstration of immunoglobulin light chain expression in formalin-fixed, paraffin-embedded tissues in approximately 80% of cases of B-cell non-Hodgkin lymphoma with a high degree of specificity and excellent interobserver reproducibility. The assay is sufficiently robust for diagnostic use in small biopsies in which fresh tissue is unavailable.