RESUMEN
BACKGROUND: Lactose tolerant test (LTT) is the most broadly used diagnostic test for lactose intolerance in Brazil, is an indirect, minimally invasive and a low-cost test that is widely available in primary care and useful in clinical practice. The C/T-13910 polymorphism in lactase persistence has been well characterized in Caucasian populations, but there are no studies evaluating the concordance between C/T-13910 polymorphism genotyping results and LTT results in Brazil, where the population is highly mixed. OBJECTIVE: We aimed to evaluate agreement between presence of C/T-13910 polymorphism genotyping and malabsorption in LTT results. METHODS: This is a retrospective analysis of a Brazilian population whose data were collected from a single laboratory database present in several Brazilian states. Results of individuals who underwent both genetic testing for lactose intolerance (C/T-13910 polymorphism genotyping) and an LTT from April 2016 until February 2019 were analysed to evaluate agreement between tests. Groups were classified according to age (<10-year-old (yo), 10-17 yo, ≥18 yo groups) and state of residence (São Paulo or Rio Grande do Sul). Results: Among the 404 patients evaluated, there was agreement between the genotyping and LTT results in 325 (80.4%) patients and discordance in 79 (19.6%) patients (k=0.42 -moderate agreement). Regarding the genotype, 47 patients with genotype C/C (lactase nonpersistence) had normal LTT results, and 32 with genotype C/T or T/T (indicating lactase persistence) had abnormal LTT results. Neither age nor state of residence (Rio Grande do Sul or São Paulo) affected the agreement between test results. CONCLUSION: Considering the moderate agreement between C/T-13910 polymorphism genotyping and LTT results (κ=0.42) in the Brazilian population, we hypothesize that an analysis of other polymorphisms could be a strategy to improve the agreement between genotyping and established tests and suggest that additional studies should focus on exploring this approach. BACKGROUND: ⢠Lactose intolerance is highly prevalent and may be implicated as a cofactor, or as a differential diagnosis, in many gastrointestinal conditions. BACKGROUND: ⢠The C/T-13910 polymorphism in lactase persistence is well characterized in Caucasian populations for lactase persistence. BACKGROUND: ⢠Concordance between genotyping and functional tests does not occur in all patients. BACKGROUND: ⢠Brazil has a highly mixed population and knowledge regarding presence of other polymorphisms is of importance in clarifying difficult cases.
Asunto(s)
Intolerancia a la Lactosa , Humanos , Niño , Prueba de Tolerancia a la Lactosa , Brasil , Intolerancia a la Lactosa/diagnóstico , Intolerancia a la Lactosa/genética , Genotipo , Estudios Retrospectivos , Lactasa/genéticaRESUMEN
ABSTRACT Background: Lactose tolerant test (LTT) is the most broadly used diagnostic test for lactose intolerance in Brazil, is an indirect, minimally invasive and a low-cost test that is widely available in primary care and useful in clinical practice. The C/T-13910 polymorphism in lactase persistence has been well characterized in Caucasian populations, but there are no studies evaluating the concordance between C/T-13910 polymorphism genotyping results and LTT results in Brazil, where the population is highly mixed. Objective: We aimed to evaluate agreement between presence of C/T-13910 polymorphism genotyping and malabsorption in LTT results. Methods: This is a retrospective analysis of a Brazilian population whose data were collected from a single laboratory database present in several Brazilian states. Results of individuals who underwent both genetic testing for lactose intolerance (C/T-13910 polymorphism genotyping) and an LTT from April 2016 until February 2019 were analysed to evaluate agreement between tests. Groups were classified according to age (<10-year-old (yo), 10-17 yo, ≥18 yo groups) and state of residence (São Paulo or Rio Grande do Sul). Results: Among the 404 patients evaluated, there was agreement between the genotyping and LTT results in 325 (80.4%) patients and discordance in 79 (19.6%) patients (k=0.42 -moderate agreement). Regarding the genotype, 47 patients with genotype C/C (lactase nonpersistence) had normal LTT results, and 32 with genotype C/T or T/T (indicating lactase persistence) had abnormal LTT results. Neither age nor state of residence (Rio Grande do Sul or São Paulo) affected the agreement between test results. Conclusion: Considering the moderate agreement between C/T-13910 polymorphism genotyping and LTT results (κ=0.42) in the Brazilian population, we hypothesize that an analysis of other polymorphisms could be a strategy to improve the agreement between genotyping and established tests and suggest that additional studies should focus on exploring this approach.
RESUMO Contexto: O teste de tolerancia à lactose (TTL) é ampliamente utilizado por ser minimamente invasivo e de baixo custo, disponível na atenção primária e muito útil na prática clínica. Está bem estabelecido o polimorfismo C/T-13910 na persistência da lactase em populações caucasianas, mas não há estudos avaliando a concordância entre os resultados da genotipagem do polimorfismo C/T-13910 e do TTL no Brasil, onde a população é altamente miscigenada. Objetivo: Avaliar a concordância entre a presença do polimorfismo C/T-13910 e a má absorção nos resultados do TTL. Métodos: Análise retrospectiva de dados coletados de um laboratorio presente em vários estados brasileiros. Os resultados dos pacientes que realizaram um teste genético para intolerância à lactose (genotipagem do polimorfismo C/T-13910) e um TTL de abril de 2016 a fevereiro de 2019 foram analisados para avaliar a concordância entre os testes. Os grupos foram classificados de acordo com a idade (<10 anos; 10-17 anos, ≥18 anos) e estado de residência (São Paulo ou Rio Grande do Sul). Resultados: Entre os 404 pacientes avaliados, houve concordância entre os resultados de genotipagem e TTL em 325 (80,4%) pacientes e discordância em 79 (19,6%) pacientes (K=0,42 - concordância moderada). Em relação ao genótipo, 47 pacientes com genótipo C/C (não persistência de lactase) apresentaram TTL normal e 32 com genótipo C/T ou T/T (indicando persistência da lactase) apresentaram TTL anormal. A idade e o estado de residência (Rio Grande do Sul ou São Paulo) não afetaram a concordância entre os resultados dos exames. Conclusão: Considerando a concordância moderada entre a genotipagem do polimorfismo C/T-13910 e os resultados de TTL (κ=0,42) na população brasileira, sugerimos que a análise de outros polimorfismos poderia ser uma estratégia para melhorar a concordância entre os testes.