Association analyses of CYP19 gene polymorphisms with height variation in a large sample of Caucasian nuclear families

Increased detection of genetic loci associated with risk predictors of osteoporotic fracture using a pleiotropic cFDR method

Although GWAS have been successful in identifying some osteoporosis associated loci, the findings explain only a small fraction of the total genetic variance. In this study we use a recently developed novel pleiotropic conditional false discovery rate (cFDR) method to identify novel genetic loci associated with two risk traits for osteoporotic fracture (the clinical outcome and end result of osteoporosis), Height (HT) and Femoral Neck (FNK) BMD. The cFDR method allows us to improve the detection of associated variants by incorporating any potentially shared genetic mechanisms between the two associated traits. We analyzed the summary statistics from two GWAS meta-analyses for single nucleotide polymorphisms (SNPs) that are associated with HT and FNK BMD. Using the cFDR method, we show enrichment in the identification of SNPs associated with each trait conditioned on their strength of association with the second trait. The findings revealed 18 SNPs that are associated with both HT and FNK BMD, 4 of which had not previously been reported to play a role in bone health. The novel SNPs located at KIF1B and the intergenic region between FERD3L and TWISTNB are noteworthy as these genes may be associated with processes that are functionally important in bone metabolism. By leveraging GWAS results from related phenotypes we identified several novel loci that may contribute to the proportion of variability explained for each trait, although we cannot speculate about these potential contributions to heritability based on this analysis alone.

Association between CYP19A1 genotype and pubertal sagittal jaw growth

INTRODUCTION

Sagittal jaw growth is influenced during puberty by a ratio of androgens and estrogens. The CYP19A1 (formerly CYP19) gene encodes the cytochrome P450 enzyme aromatase (estrogen synthetase), which converts testosterone to estrogen. Genetic variations including single nucleotide polymorphisms might regulate CYP19A1 gene expression or the function of the aromatase protein and thus influence sagittal jaw growth.

METHODS

The annual sagittal jaw growth in 92 pubertal orthodontic patients was determined by using pretreatment and posttreatment cephalometric radiographs. Single nucleotide polymorphisms rs2470144 and rs2445761 were genotyped and haplotypes constructed. Associations between genotypes or haplotypes and the annual sagittal growth were estimated by using JMP (version 9.0; SAS Institute, Cary, NC).

RESULTS

Two single nucleotide polymorphisms were significantly associated with average differences in annual sagittal jaw growth in boys. Haplotype analysis demonstrated that haplotypes T(rs2470144)T(rs2445761) and C(rs2470144)T(rs2445761) had significant effects on annual sagittal maxillary growth and on mandibular growth in boys. No association was found in girls.

CONCLUSIONS

A quantitative trait locus that influences male pubertal sagittal jaw growth might exist in the CYP19A1 gene, and single nucleotide polymorphisms rs2470144 and rs2445761 might be inside this quantitative trait locus or be linked to it.

Expression of CYP19 and CYP17 is associated with leg length, weight, and BMI

This study investigates associations between gene expressions of aromatase (CYP19), 17α hydroxylase (CYP17), and estrogen receptors α and β and anthropometric measurements in offspring of the Michigan fish eater cohort. Leg and trunk length, height, weight, and BMI and gene expression in peripheral blood cells were measured in offspring of the Michigan fish eater cohort. The parental generation was followed between 1973 and 1991, and maternal age, height, and weight data were collected. Female offspring were contacted in 2001/2002 and followed up in 2006/2007; offspring information included age, education, reproductive history, smoking, and exercise. Gene expression was standardized against 18S ribosomal ribonucleic acid (18SrRNA) and RNA polymerase II (RNA PolII) expressions. Mixed models assessed the statistical effect of gene expression on anthropometric outcomes, accounting for multiple offspring from one mother. Anthropometric measurements and gene expression were measured in 139 female offspring. The two length and the height measurements were correlated, as were BMI and weight. CYP19 expression was correlated with the other gene expressions and both estrogen receptor expressions were associated. For every 1 unit of ΔC(t) (18SrRNA - CYP19) or ΔC(t) (RNA PolII - CYP19), BMI was increased by 0.9 (P = 0.03) and 0.87 kg/m(2) (P = 0.04), respectively, and weight by 2.35 kg (P = 0.03) and 2.1 kg (P = 0.03), respectively. For every 1 unit of ΔC(t) (18SrRNA - CYP17), leg length was increased by 0.84 cm (P = 0.04). The results suggest that CYP17 gene expression may influence growth during childhood and adolescence while CYP19 may be associated with the concurrent measures of weight and BMI.

Comprehensive association analyses of IGF1, ESR2, and CYP17 genes with adult height in Caucasians

Human adult height is closely related to body growth that is regulated by multiple cytokines or hormones like growth hormone (GH) and estrogen. Our study focused on three potential candidate genes to human height, namely IGF1 (insulin-like growth factor 1), ESR2, and CYP17. We genotyped 43 single nucleotide polymorphisms (SNPs) and tested their associations in 1873 subjects from 405 nuclear families, using both the family-based quantitative transmission disequilibrium test (QTDT) and population-based ANOVA methods. Both analyses consistently detected that two novel SNPs of IGF1, rs5742694 and rs2033178, were significantly associated with human height, with the P-values of 0.0097 and 0.0057 in QTDT analyses, 0.0002/0.004 (sample 1/sample 2) and 8.46 x 10(-5)/1.92 x 10(-5) in ANOVA analyses. For ESR2, significant associations were only detected in women (rs1256061: QTDT P=0.002, ANOVA P=0.002/0.012; rs17766755: QTDT P=0.019, ANOVA P=0.023/0.006; rs1256044: QTDT P=0.022, ANOVA P=0.002/0.034). Haplotype analyses corroborated our single-SNP results. However, no association was detected between CYP17 and human height. In conclusion, we identified the important effects of IGF1 and ESR2 on adult height variation in Caucasians, and first suggested the potential sex-specific effect of ESR2 on height variation in Caucasian women. It will be valuable for other independent studies to replicate and confirm these findings.

Polymorphisms in the CYP19 gene that influence bone mineral density

Osteoporosis is a prevalent disease with a strong genetic component. Estrogens play a critical role in bone homeostasis. The aromatization of androgenic precursors is the main source of estrogens in men and postmenopausal women. Thus, aromatase is an attractive osteoporosis candidate gene. In this paper the influence of aromatase activity and aromatase gene variants on skeletal homeostasis is reviewed. The results of studies regarding the association between some common polymorphisms of the aromatase gene and bone mineral density and the risk of osteoporotic fractures are described. The mechanisms involved and the potential usefulness of those genetic data in the prevention and management of osteoporosis are discussed.

CYP19A1 polymorphisms are associated with bone mineral density in Chinese men

Aromatase-dependent biosynthesis of estrogen plays an important role in maintenance of the male skeleton, and Cytochrome p450 aromatase is the key enzyme to catalyze the conversion of androgen precursors to estrogens. We investigated the association of polymorphisms in the CYP19A1 gene and bone mineral density in a Chinese cohort. 2392 extreme low femoral neck BMD cases or extreme high femoral neck BMD controls were selected from a population-based cohort and genotyped for eight SNPs in the CYP19A1 gene. Significant associations for rs17703883, rs12594287 and rs16964201 SNPs with BMD were found in men only. Men with TC/CC genotypes in the rs17703883 SNP had a 1.5 times higher risk of having extreme low femoral neck BMD (P = 0.003, empirical P value = 0.05), and decreased BMDs at total body (P = 0.004, empirical P value = 0.07) and total hip (P = 0.003, empirical P value = 0.05). Men carrying AA/AG genotypes in the rs12594287 SNP had a 30% reduced risk of having extreme low femoral neck BMD (P = 0.007, empirical P value = 0.12), and increased BMDs at total body (P = 0.0009, empirical P value = 0.018) and total hip (P = 0.001, empirical P value = 0.02). Men carrying TT/TC genotypes in the rs16964201 SNP had a 40% reduced risk of having extreme low femoral neck BMD (P = 0.005, empirical P value = 0.087), and increased BMDs at total body (P = 0.0001, empirical P value = 0.002) and total hip (P = 0.0006, empirical P value = 0.012). Haplotype analysis showed that the G-C-T-A-T haplotype was significantly related to higher BMD. Our finding suggests that genetic variations in the CYP19A1 gene are significantly associated with BMD at different skeletal sites in adult men, but not in women.