RESUMO
BACKGROUND AND AIMS: The role of nutrition in the pathogenesis of colorectal cancer is not fully understood. Milk products are an essential part of human nutrition in Western countries. Absorption of lactose, the main sugar of milk, is regulated by the activity of the lactase enzyme in the gut wall. The activity of lactase is genetically determined and is associated with a C/T single nucleotide polymorphism residing 13910 bp upstream of the lactase coding sequence. Here we have studied the relationship between the C/T(-13910) polymorphism and colorectal cancer in Finnish, British, and Spanish populations. PATIENTS AND METHODS: A total of 2766 subjects, including 963 Finnish, 283 British, and 163 Spanish subjects with colorectal cancer, and 773 Finnish, 363 British, and 221 Spanish control subjects, were genotyped for the C/T(-13910) variant by polymerase chain reaction minisequencing. RESULTS: The C/C(-13910) genotype, which is a robust molecular marker of low lactase activity (lactase non-persistence), was found to significantly associate with the risk of colorectal cancer (p = 0.015) in the Finnish subjects, with an odds ratio of 1.40 (95% confidence interval 1.07-1.85). No association was found with site, histology, or stage of the tumour. No significant risk was detected in the British or Spanish populations. CONCLUSION: Low lactase enzyme activity, defined by genotyping of the C/T(-13910) variant, may increase the risk of colorectal cancer. Further studies are warranted to investigate the role of milk and other dairy products in the pathogenesis of colon cancer in different populations.
Assuntos
Neoplasias Colorretais/genética , Predisposição Genética para Doença , Lactase/genética , Adulto , Idoso , Idoso de 80 Anos ou mais , Neoplasias Colorretais/enzimologia , Neoplasias Colorretais/etnologia , Feminino , Finlândia/epidemiologia , Genótipo , Humanos , Lactase/deficiência , Lactase/metabolismo , Masculino , Pessoa de Meia-Idade , Estadiamento de Neoplasias , Fenômenos Fisiológicos da Nutrição , Reação em Cadeia da Polimerase/métodos , Polimorfismo de Nucleotídeo Único , Fatores de Risco , Espanha/epidemiologia , Reino Unido/epidemiologiaRESUMO
BACKGROUND/AIMS: Adult-type hypolactasia (primary lactose malabsorption) affects most of world's human population and limits the use of fresh milk due to lactose intolerance. The diagnosis of adult-type hypolactasia has been difficult to establish because of unsatisfactory diagnostic methods. C/T(-13910) single nucleotide polymorphism residing 13910 base pairs from the 5' end of the lactase gene has been shown to be associated with lactase persistence. The aim of the study was to assess the applicability of the C/T(-13910) variant as a diagnostic test for adult-type hypolactasia during childhood. METHODS: Intestinal biopsies were obtained from 329 children and adolescents of African, Finnish, and other White origins aged 0.1-20 years undergoing upper gastrointestinal endoscopy because of abdominal complaints. The biopsies were assayed for lactase, sucrase, and maltase activity and genotyped for the C/T(-13910) variant using polymerase chain reaction minisequencing. RESULTS: The frequency of the C/C(-13910) genotype defining lactase non-persistence was well in agreement in this study with published figures for the prevalences of adult-type hypolactasia in Africans and Whites. The C/C(-13910) genotype was associated with very low lactase activity (<10 U/g protein) in the majority of children tested at 8 years of age and in every child older than 12 years of age giving a specificity of 100% and sensitivity of 93% for the genetic test. The decline of lactase activity was somewhat earlier in African compared with Finnish children with C/C(-13910) genotype (p<0.03). CONCLUSIONS: Genetic test of C/T(-13910) polymorphism can be used as a first stage screening test for adult-type hypolactasia.
Assuntos
Testes Genéticos/métodos , Lactase/genética , Intolerância à Lactose/diagnóstico , Adolescente , Adulto , Distribuição por Idade , Animais , População Negra/genética , Criança , Pré-Escolar , Dissacaridases/metabolismo , Feminino , Finlândia/epidemiologia , Genótipo , Humanos , Lactente , Intestinos/enzimologia , Intolerância à Lactose/etnologia , Intolerância à Lactose/genética , Masculino , Leite/efeitos adversos , Polimorfismo de Nucleotídeo Único , Valor Preditivo dos Testes , Prevalência , Sensibilidade e EspecificidadeRESUMO
OBJECTIVE: Lactase persistence (LP), the ability to maintain a high lactase activity throughout life, has been suggested to be a possible risk factor for diabetes. Recently, a single nucleotide polymorphism C (-13910) T, residing 14 kb from the 5' end of the lactase (LCT) gene was shown to be associated with LP. Here we have studied the relationship between C (13910) T polymorphism and diabetes in the Finnish population. PATIENTS AND DESIGN: In all, 1455 patients with type I and 615 with type II diabetes and 446 nondiabetic controls in the Finnish population were genotyped for the C (-13910) T polymorphism by PCR minisequencing. RESULTS: No differences were detected in the LP genotype frequencies (CT&TT) between diabetic and nondiabetic subjects. CONCLUSIONS: We conclude that the C (-13910) T polymorphism associated with lifelong LP is not a risk factor for type I or type II diabetes in the Finnish population.
