Identifying pleiotropic variants and candidate genes for fertility and reproduction traits in Holstein cattle via association studies based on imputed whole-genome sequence genotypes.

BACKGROUND: Genetic progress for fertility and reproduction traits in dairy cattle has been limited due to the low heritability of most indicator traits. Moreover, most of the quantitative trait loci (QTL) and candidate genes associated with these traits remain unknown. In this study, we used 5.6 million imputed DNA sequence variants (single nucleotide polymorphisms, SNPs) for genome-wide association studies (GWAS) of 18 fertility and reproduction traits in Holstein cattle. Aiming to identify pleiotropic variants and increase detection power, multiple-trait analyses were performed using a method to efficiently combine the estimated SNP effects of single-trait GWAS based on a chi-square statistic. RESULTS: There were 87, 72, and 84 significant SNPs identified for heifer, cow, and sire traits, respectively, which showed a wide and distinct distribution across the genome, suggesting that they have relatively distinct polygenic nature. The biological functions of immune response and fatty acid metabolism were significantly enriched for the 184 and 124 positional candidate genes identified for heifer and cow traits, respectively. No known biological function was significantly enriched for the 147 positional candidate genes found for sire traits. The most important chromosomes that had three or more significant QTL identified are BTA22 and BTA23 for heifer traits, BTA8 and BTA17 for cow traits, and BTA4, BTA7, BTA17, BTA22, BTA25, and BTA28 for sire traits. Several novel and biologically important positional candidate genes were strongly suggested for heifer (SOD2, WTAP, DLEC1, PFKFB4, TRIM27, HECW1, DNAH17, and ADAM3A), cow (ANXA1, PCSK5, SPESP1, and JMJD1C), and sire (ELMO1, CFAP70, SOX30, DGCR8, SEPTIN14, PAPOLB, JMJD1C, and NELL2) traits. CONCLUSIONS: These findings contribute to better understand the underlying biological mechanisms of fertility and reproduction traits measured in heifers, cows, and sires, which may contribute to improve genomic evaluation for these traits in dairy cattle.

[Diagnosis of overweight and obesity in schoolchildren: utilization of the body mass index international standard]. / Diagnóstico de sobrepeso e obesidade em escolares: utilização do índice de massa corporal segundo padrão internacional.

OBJECTIVE: To evaluate the agreement between the body mass index international standard and body fat for the diagnosis of overweight and obesity in schoolchildren. METHODS: 528 schoolchildren between 6 and 10 years of age, of both sexes, had their weight and height measured. They were then classified as normal, underweight, overweight or obese using the body fat index for age. Body fat was estimated based on the sum of triceps and subscapular, triceps and calf skinfold measurements and waist and hip circumference. RESULTS: Overweight and obesity were found in 21.2% of the girls and 18.8% of the boys. The average percentage of body fat in the normal children (17.7%) was statistically different from that of overweight (27%) and obese (29.4%) children (p < 0.02). The average waist and hip circumference also differed significantly between normal boys and girls (56.9 cm and 67.7 cm) and overweight children (65.9 cm and 77 cm) (p < 0.01). There was no significant difference between groups in terms of average waist to hip ratio. The percentage of body fat, waist and hip circumference were significantly correlated with body mass index (p < 0.01). CONCLUSION: Body mass index for age was an adequate indicator of overweight and obesity in group studied, with a good agreement with body fat.

Diagnóstico de sobrepeso e obesidade em escolares: utilização do índice de massa corporal segundo padrão internacional / Diagnosis of overweight and obesity in schoolchildren: utilization of the body mass index international standard

OBJETIVO: Avaliar a concordância entre o índice de massa corporal segundo padrão internacional e indicadores de adiposidade no diagnóstico de sobrepeso e obesidade em escolares. MÉTODOS: Avaliação de peso e estatura de 528 escolares, entre 6 e 10 anos, de ambos os sexos, seguida da classificação das crianças em eutróficas, com baixo peso, sobrepeso ou obesidade segundo índice de massa corporal por idade. A adiposidade foi estimada a partir da somatória das medidas das dobras cutâneas tricipital e subescapular, tricipital e da panturrilha medial e pelas circunferências da cintura e quadril. RESULTADOS: a prevalência de sobrepeso e obesidade foi de 21,2 por cento nas meninas e 18,8 por cento nos meninos. A porcentagem de gordura corporal média nas crianças normais (17,7 por cento) foi significativamente diferente da observada nas crianças com sobrepeso (27,0 por cento) e obesidade (29,4 por cento) (p < 0,02). As circunferências médias da cintura e quadril dos meninos e meninas eutróficos (56,9 cm e 67,7 cm) diferiu significativamente daqueles com sobrepeso (65,9 cm e 77 cm) (p < 0,01). Não houve diferença na razão cintura-quadril entre os grupos. A porcentagem de gordura corporal, a circunferência da cintura e a circunferência do quadril correlacionaram-se significativamente com o índice de massa corporal (p < 0,01). CONCLUSAO: O uso do índice de massa corporal por idade, baseado em padrão internacional, mostrou-se adequado para o diagnóstico de sobrepeso e obesidade na faixa etária estudada, apresentando boa concordância com a adiposidade.