Frequência alélica da deleção no gene POMC responsável pela obesidade em cães da raça Labrador Retriever no Brasil
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Data
2019-05-28
Autores
Lourenço, Natália de Oliveira [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
O Labrador Retriever (LR) é uma das principais raças caninas com maior predisposição à obesidade. Vários fatores, especialmente as inter-relações entre a alimentação, exercício e fatores sociais, influenciam a probabilidade de um cão se tornar obeso. Além disso, fatores genéticos são também responsáveis pela obesidade em cães, e no LR a mutação P187fs no gene pró-opiomelanocortina (POMC) está fortemente associada à obesidade. Não existem estudos prévios de prevalência da desta em LR no Brasil. Portanto, o objetivo deste estudo foi investigar esta mutação em cães da raça LR no Brasil. Dos 108 LR avaliados neste estudo, 59 eram de um estudo retrospectivo (composto por animais atendido no hospital veterinário e sem linhagem conhecida) e 49 eram de um estudo prospectivo (composto por 19 cães pet e 30 cães de assistência/resgate). Um questionário de risco de obesidade modificado foi aplicado nos tutores dos animais usados no estudo prospectivo. Fragmentos de DNA, contendo a região mutada, foram amplificados por PCR e submetidos ao sequenciamento gênico direto. A frequência alélica da mutação (21,3%) estava fora do equilíbrio de Hardy-Weinberg (P < 0,05). Usando somente os dados dos animais de linhagem conhecida, o alelo mutado foi mais frequente no grupo de assistência/resgate que no grupo de pets (P < 0,01). Embora a mutação tenha aumentado a motivação pelo alimento em LR do grupo de assistência/resgate, outras variáveis, especialmente o frequente exercício, favoreceu a manutenção o peso corporal ideal. O desequilíbrio de Hardy-Weinberg observado na distribuição do alelo mutado observado neste estudo, independentemente do grupo de LR, sugere a possibilidade de uma seleção positiva para este alelo, o qual poderá levar a manutenção desse alelo deletério nesta população.
The Labrador retriever (LR) is among the main breeds with the greatest predisposition to obesity. Several factors; especially the interrelationships between food management, exercise and social factors; influence the likelihood of a dog becoming obese. Furthermore, genetic factors are also responsible for obesity in dogs, and in LR, the mutation P187fs in pro-opiomelanocortin (POMC) gene is strongly associated with obesity. There is no knowledge of studies that have previously evaluated the prevalence of this mutation in Brazilian LR. Therefore, the objective of this study was to investigate this mutation in LR in Brazil. Of the 108 LR that were assessed in this study, 59 were from a previous study, composed by animals assisted in a veterinary hospital with unknown lineage, and 49 were from a prospective study, composed of 19 pet and 30 assistance/rescue LR dogs. The obesity risk and appetite questionnaire were applied, with some modifications, to tutors of the animals used in the prospective study. Fragments of the DNA, containing the mutated region, were amplified by PCR and submitted to direct gene sequencing. The mutated allele frequency (21.3%) was out of Hardy-Weinberg Equilibrium (HWE) (P < 0.05). Using only the data of animals with known lineage, the presence of the mutated allele was higher in the assistance/rescue dogs than pets (P < 0.01). Although the mutation has increased the food-motivation in the assistance/rescue dogs, other variables, especially frequent exercising, favored that these animals maintained the ideal body weight. In summary, the Hardy-Weinberg disequilibrium observed in the mutated allele distribution in this study, independently of the LR group assessed, suggesting the possibility of positive selection of the mutated allele, which may lead to the maintenance of this deleterious allele in this population.
The Labrador retriever (LR) is among the main breeds with the greatest predisposition to obesity. Several factors; especially the interrelationships between food management, exercise and social factors; influence the likelihood of a dog becoming obese. Furthermore, genetic factors are also responsible for obesity in dogs, and in LR, the mutation P187fs in pro-opiomelanocortin (POMC) gene is strongly associated with obesity. There is no knowledge of studies that have previously evaluated the prevalence of this mutation in Brazilian LR. Therefore, the objective of this study was to investigate this mutation in LR in Brazil. Of the 108 LR that were assessed in this study, 59 were from a previous study, composed by animals assisted in a veterinary hospital with unknown lineage, and 49 were from a prospective study, composed of 19 pet and 30 assistance/rescue LR dogs. The obesity risk and appetite questionnaire were applied, with some modifications, to tutors of the animals used in the prospective study. Fragments of the DNA, containing the mutated region, were amplified by PCR and submitted to direct gene sequencing. The mutated allele frequency (21.3%) was out of Hardy-Weinberg Equilibrium (HWE) (P < 0.05). Using only the data of animals with known lineage, the presence of the mutated allele was higher in the assistance/rescue dogs than pets (P < 0.01). Although the mutation has increased the food-motivation in the assistance/rescue dogs, other variables, especially frequent exercising, favored that these animals maintained the ideal body weight. In summary, the Hardy-Weinberg disequilibrium observed in the mutated allele distribution in this study, independently of the LR group assessed, suggesting the possibility of positive selection of the mutated allele, which may lead to the maintenance of this deleterious allele in this population.
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Palavras-chave
Mutação, Cão, Obesidade, Prevalência, Brasil, Mutation, Dog, Obesity, Prevalence, Brazil