Haplotypes of intron 4 of the estrogen receptor alpha gene and hip fractures: a replication study in Caucasians

Intronic SNP in ESR1 encoding human estrogen receptor alpha is associated with brain ESR1 mRNA isoform expression and behavioral traits

Genetic variants of ESR1 have been implicated in multiple diseases, including behavioral disorders, but causative variants remain uncertain. We have searched for regulatory variants affecting ESR1 expression in human brain, measuring allelic ESR1 mRNA expression in human brain tissues with marker SNPs in exon4 representing ESR1-008 (or ESRα-36), and in the 3'UTR of ESR1-203, two main ESR1 isoforms in brain. In prefrontal cortex from subjects with bipolar disorder, schizophrenia, and controls (n = 35 each; Stanley Foundation brain bank), allelic ESR1 mRNA ratios deviated from unity up to tenfold at the exon4 marker SNP, with large allelic ratios observed primarily in bipolar and schizophrenic subjects. SNP scanning and targeted sequencing identified rs2144025, associated with large allelic mRNA ratios (p = 1.6E10-6). Moreover, rs2144025 was significantly associated with ESR1 mRNA levels in the Brain eQTL Almanac and in brain regions in the Genotype-Tissue Expression project. In four GWAS cohorts, rs2104425 was significantly associated with behavioral traits, including: hypomanic episodes in female bipolar disorder subjects (GAIN bipolar disorder study; p = 0.0004), comorbid psychological symptoms in both males and females with attention deficit hyperactivity disorder (GAIN ADHD, p = 0.00002), psychological diagnoses in female children (eMERGE study of childhood health, subject age ≥9, p = 0.0009), and traits in schizophrenia (e.g., grandiose delusions, GAIN schizophrenia, p = 0.0004). The first common ESR1 variant (MAF 12-33% across races) linked to regulatory functions, rs2144025 appears conditionally to affect ESR1 mRNA expression in the brain and modulate traits in behavioral disorders.

Polymorphisms in Genes of Relevance for Oestrogen and Oxytocin Pathways and Risk of Barrett's Oesophagus and Oesophageal Adenocarcinoma: A Pooled Analysis from the BEACON Consortium

BACKGROUND

The strong male predominance in oesophageal adenocarcinoma (OAC) and Barrett's oesophagus (BO) continues to puzzle. Hormonal influence, e.g. oestrogen or oxytocin, might contribute.

METHODS

This genetic-epidemiological study pooled 14 studies from three continents, Australia, Europe, and North America. Polymorphisms in 3 key genes coding for the oestrogen pathway (receptor alpha (ESR1), receptor beta (ESR2), and aromatase (CYP19A1)), and 3 key genes of the oxytocin pathway (the oxytocin receptor (OXTR), oxytocin protein (OXT), and cyclic ADP ribose hydrolase glycoprotein (CD38)), were analysed using a gene-based approach, versatile gene-based test association study (VEGAS).

RESULTS

Among 1508 OAC patients, 2383 BO patients, and 2170 controls, genetic variants within ESR1 were associated with BO in males (p = 0.0058) and an increased risk of OAC and BO combined in males (p = 0.0023). Genetic variants within OXTR were associated with an increased risk of BO in both sexes combined (p = 0.0035) and in males (p = 0.0012). We followed up these suggestive findings in a further smaller data set, but found no replication. There were no significant associations between the other 4 genes studied and risk of OAC, BO, separately on in combination, in males and females combined or in males only.

CONCLUSION

Genetic variants in the oestrogen receptor alpha and the oxytocin receptor may be associated with an increased risk of BO or OAC, but replication in other large samples are needed.

COL1A1 haplotypes and hip fracture

Fragility fractures resulting from low-trauma events such as a fall from standing height are associated with osteoporosis and are very common in older people, especially women. Three single nucleotide polymorphisms (SNPs) at the COL1A1 gene (rs1107946, rs11327935, and rs1800012) have been widely studied and previously associated with bone mineral density (BMD) and fracture. A rare haplotype (T-delT-T) of these three SNPs was found to be greatly overrepresented in fractured individuals compared with nonfractured controls, thus becoming a good candidate for predicting increased fracture risk. The aim of our study was to assess the association of this haplotype with fracture risk in Spanish individuals. We recruited two independent groups of ∼100 patients with hip fracture (a total of 203 individuals) and compared the genotype and haplotype distributions of the three SNPs in the fractured patients with those of 397 control individuals from the BARCOS Spanish cohort. We found no association with risk of fracture at the genotype level for any of the SNPs, and no differences in the SNP frequencies between the two groups. At the haplotype level, we found no association between the T-delT-T haplotype and fracture. However, we observed a small but significant (p = 0.03) association with another rare haplotype, G-insT-T, which was slightly overrepresented in the patient group.

Genetic polymorphisms of the Wnt receptor LRP5 are differentially associated with trochanteric and cervical hip fractures

Epidemiological studies suggest that cervical and trochanteric hip fractures have different pathogenesis. We tested the hypothesis that genetic factors have different influences on both types of fractures. Ten polymorphisms of genes known to play an important role in skeletal homeostasis [estrogen receptor alpha (ESR1), aromatase (CYP19A1), type I collagen (COL1A1), and lipoprotein receptor-related protein 5 (LRP5)] were analyzed in 471 Spanish patients with fragility hip fractures. Two polymorphisms of the LRP5 gene (rs7116604 and rs3781600) were associated with the type of fracture (P = 0.0085 and 0.0047, respectively). The presence of rare alleles at each locus was associated with trochanteric fractures over cervical fractures (OR = 1.7 in individuals with at least one rare allele at rs7116604 or rs3781600 loci in comparison with the common homozygotes). Considering individuals bearing the four common alleles as reference, the OR for trochanteric fractures was 1.6 in those with one or two rare alleles and 7.5 in those with three or four rare alleles (P for trend = 0.0074), which is consistent with an allele-dosage effect. There were no significant differences in the frequency distributions of the ESR1, CYP19A1, and COL1A1 genotypes between trochanteric and cervical fractures in either the original group or an extended group of 818 patients. These results suggest that LRP5 alleles influence the type of hip fractures. They support the view that different genetic factors are involved in cervical and trochanteric fractures, which should be taken into consideration in future genetic association studies.