RESUMEN
Prader-Willi (PWS) and Angelman (AS) syndromes are two clinically distinct imprinted disorders characterized by genetic abnormalities at 15q11-q13. Early diagnosis of both syndromes provides improved treatment and accurate genetic counseling. Whole blood (WB) is the most common DNA source of many methodologies to detect PWS and AS, however, the need of WB makes a massive screening difficult in newborns due to economic and technical limitations. The aim of this study was to adapt a Methylation-sensitive High-Resolution Melting (MS-HRM) approach from dried blood spot (DBS) samples, assessing the different DNA isolation techniques and diagnostic performance. Over a 1-year period, we collected 125 DBS cards, of which 45 had already been diagnosed by MS-HRM (20 PWS, 1 AS, and 24 healthy individuals). We tested three different DBS-DNA extraction techniques assessing the DNA concentration and quality, followed by MS-HRM and statistical comparison. Each DBS-DNA extraction method was capable of accuracy in detecting all PWS and AS individuals. However, the efficiency to detect healthy individuals varied according to methodology. In our experience, DNA extracted from DBS analyzed by the MS-HRM methodology provides an accurate approach for genetic screening of imprinting related disorders in newborns, offering several benefits compared to traditional whole blood methods.
Asunto(s)
Síndrome de Angelman/sangre , Síndrome de Angelman/genética , Metilación de ADN/genética , Pruebas con Sangre Seca , Tamizaje Neonatal , Desnaturalización de Ácido Nucleico/genética , Síndrome de Prader-Willi/sangre , Síndrome de Prader-Willi/genética , Autoantígenos/genética , Humanos , Recién Nacido , Proyectos Piloto , Ribonucleasa P/genéticaRESUMEN
OBJECTIVE: To analyze the confirmed or not-confirmed cases of neonatal screening (CH) screened in the Programa "Primeiros Passos", stratifying them into TSH blood-spot (TSH-BS) ranges. MATERIALS AND METHODS: To stratify, in ranges of TSH-BS as a function of TSH serum (TSH-S), the cases called for a confirmatory test from January, 2006 to July, 2009. RESULTS: Around 37% of the confirmed cases (475) showed TSH-F > 9.5 mUi/L, but most of the confirmed cases were in lower TSH-F ranges. Among the unconfirmed cases (4,613), most were found in the lower ranges. There was no TSH-F range exclusive to unconfirmed cases. CONCLUSION: TSH-BS cutoff value used is crucial in the diagnosis of CH and should be low, even if more confirmatory tests are performed. More studies are needed to determine the best cutoff value of TSH-BS for neonatal screening.
Asunto(s)
Hipotiroidismo Congénito/diagnóstico , Tamizaje Neonatal/métodos , Tirotropina/sangre , Biomarcadores/sangre , Brasil , Humanos , Recién Nacido , Programas Nacionales de Salud , Valores de Referencia , Estudios RetrospectivosRESUMEN
OBJETIVO: Analisar casos de hipotireoidismo congênito (HC) confirmados ou não, triados pelo Programa "Primeiros Passos", estratificando-os em faixas de TSH em filtro (TSH-F). MATERIAIS E MÉTODOS: Estratificar, em faixas de TSH-F em função do TSH em soro (TSH-S), os casos convocados para teste confirmatório de janeiro/2006 a julho/2009. RESULTADOS: Cerca de 37% dos casos confirmados (475) apresentaram TSH-F > 9,5 mUi/L, mas a maioria dos casos confirmados estava nas faixas de TSH-F mais baixas. Entre os casos não confirmados (4.613), a maior parte se encontrava nas faixas mais baixas. Não houve faixa de TSH-F exclusiva dos casos não confirmados. CONCLUSÃO: O valor de corte do TSH-F utilizado é fundamental no diagnóstico do HC e deve ser baixo, mesmo que sejam realizados mais testes confirmatórios. Mais estudos são necessários para determinar o melhor valor de corte de TSH-F para triagem neonatal.
OBJECTIVE: To analyze the confirmed or not-confirmed cases of neonatal screening (CH) screened in the Programa "Primeiros Passos", stratifying them into TSH blood-spot (TSH-BS) ranges. MATERIALS AND METHODS: To stratify, in ranges of TSH-BS as a function of TSH serum (TSH-S), the cases called for a confirmatory test from January, 2006 to July, 2009. RESULTS: Around 37% of the confirmed cases (475) showed TSH-F > 9.5 mUi/L, but most of the confirmed cases were in lower TSH-F ranges. Among the unconfirmed cases (4,613), most were found in the lower ranges. There was no TSH-F range exclusive to unconfirmed cases. CONCLUSION: TSH-BS cutoff value used is crucial in the diagnosis of CH and should be low, even if more confirmatory tests are performed. More studies are needed to determine the best cutoff value of TSH-BS for neonatal screening.
