Abstract Introduction: Colorectal cancer (CRC) is a complex disease due to the large number of factors that influence its development, including variants in tumor suppressor genes. Objective: To estimate allelic and genotypic frequencies of c.3915G>A and c.5371G>A variants of the TSC2 gene in a Mexican population with CRC, as well as to analyze their association with the development of CRC. Methods: 126 peripheral blood samples from patients diagnosed with sporadic CRC and 134 from healthy individuals, regarded as the control group, were included. Identification of genotypes was carried out using traditional PCR and enzymatic digestion. All individuals signed an informed consent letter. Results: The A allele of the c.3915G>A variant (OR = 0.31, 95% CI = 0.15-0.69, p = 0.004), as well as A/G haplotype of the c.3915G>A and c.5371G>A variants (OR = 0.28, 95% CI = 0.12-0.68, p = 0.005) showed a possible protective effect against sporadic CRC. In silico analysis indicated that both variants generate modifications in the splicing process. Conclusion: The presence of TSC2 gene c.3915G>A variant suggests a possible protective effect against sporadic CRC in the Mexican population; however, no association was observed with the c.5371G>A variant.

Resumen Introducción: El cáncer colorrectal (CCR) es una enfermedad compleja debido al gran número de factores que influyen en su desarrollo, incluyendo variantes en genes supresores de tumores. Objetivo: Estimar las frecuencias alélicas y genotípicas de las variantes c.3915G>A y c.5371G>A del gen TSC2 en una población mexicana con CCR, así como analizar la asociación con el desarrollo de CCR. Métodos: Se incluyeron 126 muestras de sangre periférica de pacientes con diagnóstico de CCR esporádico y 134 de individuos sanos, considerados como grupo de control. La identificación de los genotipos se llevó a cabo mediante PCR tradicional y digestión enzimática. Todos los individuos firmaron una carta de consentimiento informado. Resultados: El alelo A de la variante c.3915G>A (RM = 0.31, IC 95 % = 0.15-0.69, p = 0.004), así como el haplotipo A/G de las variantes c.3915G>A y c.5371G>A (RM = 0.28, IC 95 % = 0.12-0.68, p = 0.005) mostraron un posible efecto protector contra CCR esporádico. El análisis in silico indicó que ambas variantes generan modificaciones en el proceso de corte y empalme. Conclusión: La presencia de la variante c.3915G>A del gen TSC2 sugiere un posible efecto protector contra CCR esporádico en población mexicana; sin embargo, no se observó esta asociación con la variante c.5371G>A.

Abstract Introduction Attention deficit hyperactivity disorder (ADHD) is one of the most common neuropsychiatric conditions in childhood and a multifactorial condition attributable to genetic and/or environmental influence. Allelic variants in the serotonin transporter gene (SLC6A4) have been associated to lower transcriptional efficiency, changes in serotonin concentration in several brain regions, and ADHD development. Objective To identify the association between the SLC6A4 alleles and ADHD diagnosis and risk factor phenotypes in children from a Mexican mestizo population. Method In this study, 134 unrelated children were included and evaluated for ADHD, genotypification for the 5HTTLPR polymorphism, and identification of multiple phenotypes from their clinical records and family background for association analysis. Results The following distribution of genotypes was observed: 23% SS, 49% SL, and 28% LL. From the phenotypes evaluated in the present study, gestational diabetes mellitus (p = .045), history of epilepsy (p = .047), and parental substance abuse (p = .033) showed an association with ADHD development in regression analysis along with the S variant. Discussion and conclusion Results suggest that interaction of the S allele and some of the phenotypes analyzed may play a relevant role in the development of ADHD in the studied population.

Resumen Introducción El trastorno por déficit de atención e hiperactividad (TDAH) es uno de los padecimientos neuropsiquiátricos más comunes en la infancia. Como su naturaleza es multifactorial, es atribuible a influencias genéticas y/o ambientales. Las variantes alélicas del gen transportador de serotonina (SLC6A4) se han asociado previamente con cambios en los niveles de serotonina en algunas regiones cerebrales, así como con el desarrollo de TDAH. Objetivo Identificar la posible asociación entre los alelos del gen SLC6A4 y el diagnóstico de TDAH, así como factores de riesgo en niños mestizos mexicanos. Método En el presente estudio se incluyeron 134 niños, los cuales fueron evaluados para TDAH, genotipificación del polimorfismo 5HTTLPR e identificación de múltiples fenotipos en su historia clínica y antecedentes familiares para su análisis de asociación estadística. Resultados Se mostró la siguiente distribución de genotipos: 23% SS, 49% SL y 28% LL. En un modelo de regresión, los fenotipos de diabetes mellitus gestacional (p = .045), historia de epilepsia (p = .047) y el abuso de sustancias de los padres (p = .033) mostraron asociación con la variante S y el desarrollo de TDAH. Discusión y conclusión El presente estudio sugiere que el alelo S en conjunto con algunos fenotipos puede cumplir un papel importante en el desarrollo de TDAH en nuestra población.

The serotonergic system has been hypothesized to contribute to the biological susceptibility to type 2 diabetes mellitus (T2DM) and body-mass index (BMI) categories. We investigate a possible association of 5-HTTLPR polymorphism (L and S alleles) in the promoter region of the serotonin transporter gene (SLC6A4) with the development of T2DM and/or higher BMI by analyzing a sample of 138 individuals diagnosed with T2DM and 172 unrelated controls from the Mexican general population. In the total sample genotypes were distributed according to Hardy- Weinberg equilibrium, and S allele frequency was 0.58. There was no statistical association between 5-HTTLPR polymorphism and the development of T2DM in this Mexican population sample (p = 0.12). Nevertheless, logistic regression analysis of the L allele and increased BMI disclosed an association, after adjusting for age, sex and T2DM (p = 0.02, OR 1.74, 95% CI: 1.079-2.808).