ABSTRACT
Familial hypercholesterolemia (FH) is associated with mutations in the low-density lipoprotein (LDL) receptor (LDLR), apolipoprotein B (APOB), and proprotein convertase subtilisin/kexin 9 (PCSK9) genes. A pathological variant has not been identified in 30-70% of clinically diagnosed FH patients, and a burden of LDL cholesterol (LDL-c)-raising alleles has been hypothesized as a potential cause of hypercholesterolemia in these patients. Our aim was to study the distribution of weighted LDL-c-raising single-nucleotide polymorphism (SNP) scores (weighted gene scores or wGS) in a population recruited in a clinical setting in Catalonia. The study included 670 consecutive patients with a clinical diagnosis of FH and a prior genetic study involving 250 mutation-positive (FH/M+) and 420 mutation-negative (FH/M-) patients. Three wGSs based on LDL-c-raising variants were calculated to evaluate their distribution among FH patients and compared with 503 European samples from the 1000 Genomes Project. The FH/M- patients had significantly higher wGSs than the FH/M+ and control populations, with sensitivities ranging from 42% to 47%. A wGS based only on the SNPs significantly associated with FH (wGS8) showed a higher area under the receiver operating characteristic curve, and higher diagnostic specificity and sensitivity, with 46.4% of the subjects in the top quartile. wGS8 would allow for the assignment of a genetic cause to 66.4% of the patients if those with polygenic FH are added to the 37.3% of patients with monogenic FH. Our data indicate that a score based on 8 SNPs and the75th percentile cutoff point may identify patients with polygenic FH in Catalonia, although with limited diagnostic sensitivity and specificity.
ABSTRACT
Introducción. La metilación del ácido desoxirribonucleico (ADN) es una rama de la epigenética que puede ser útil para la identificación, incluso precoz, del cáncer de pulmón. El objetivo del estudio fue evaluar la sensibilidad, especificidad y rendimiento diagnóstico de un panel de metilación formado por los genes APC (adenomatous polyposis coli), DAPK (death associated protein kinase) y RASSF1A (Ras association domain familiy 1A) asociado a la citología habitual en broncoaspirados (BAS) de pacientes con sospecha de cáncer de pulmón. Material y métodos. Se seleccionaron 39 BAS, 24 positivos y 15 negativos, para cáncer de pulmón de diferentes tipos y estadios. Las citosinas de las muestras se transformaron en uracilos con bisulfito sódico, se efectuó una doble reacción en cadena de la polimerasa (PCR) (bisulfite conversion specific-methylation specific PCR) y se identificó el estado de metilación mediante electroforesis. Resultados. APC resultó metilado en 2 de los 24 tumores pulmonares (8%), DAPK en 0 de 24 (0%) y RASSF1A en 9 de 23 (39%). La sensibilidad total del panel fue del 37,5% (9 de 24). No se detectó metilación en ninguna de las muestras libres de cáncer de pulmón (0 de 15), por lo que la especificidad fue del 100%. Además, el panel detectó metilación en una de las 7 muestras de cáncer primario de pulmón, cuya prueba citológica había sido negativa (14%) y en 3 de las 5 muestras con cáncer de pulmón con citologías meramente sospechosas (60%). Su contribución al diagnóstico correcto ante pruebas citológicas sospechosas o discordantes con el diagnóstico final fue del 33% (4 de 12). Conclusiones. La metilación del ADN puede ser un arma útil en el diagnóstico del cáncer de pulmón. Hasta el momento, la sensibilidad en el panel escogido depende exclusivamente de RASSF1A. Nuevos estudios son necesarios para garantizar la reproducibilidad y optimizar su sensibilidad (AU)
Introduction. DNA methylation is a part of epigenetics that can be useful for lung cancer detection even at early stages. The aim of this study was to evaluate sensitivity, specificity and diagnostic capacity of a methylation panel including APC, DAPK and RASSF1A genes, together with routine cytology tests in patients suspected with lung cancer. Material and methods. We selected 39 bronchoaspirates, 24 positive and 15 negative for lung cancer of different histological types and stages. Samples were transformed with sodium bisulphite. A double PCR (BS-MSP) was performed and methylation status was identified by electrophoresis. Results. APC was found to be methylated in 2 out of 24 lung tumours (8%), DAPK in 0 out of 24 (0%) and RASSF1A in 9 out of 23 (39%). Panel sensibility was 37.5% (9/24). No methylation was detected in any of the negative lung cancer samples (0/15), so specificity was 100%. Moreover, the panel detected methylation in 1 of the 7 primary lung cancer tumour samples in which the cytology test was negative (14%) and in 3 of 5 lung cancer tumour samples in which cytology test was only suspicious (60%). Its contribution to the correct diagnosis when cytology tests were suspicious or discordant with final diagnosis was 33% (4/12). Conclusions. DNA methylation can be a useful tool in lung cancer diagnosis. The chosen panel sensibility depends exclusively on RASSF1A to date. Consequently, new studies are required to guarantee reproducibility and optimize sensitivity (AU)
