In the version of this article initially published, in Fig. 5a, the data in the right column of 'DAAM2 gRNA1' were incorrectly plotted as circles indicating 'untreated' rather than as squares indicating 'treated'. The error has been corrected in the HTML and PDF versions of the article.
Osteoporosis is a common aging-related disease diagnosed primarily using bone mineral density (BMD). We assessed genetic determinants of BMD as estimated by heel quantitative ultrasound in 426,824 individuals, identifying 518 genome-wide significant loci (301 novel), explaining 20% of its variance. We identified 13 bone fracture loci, all associated with estimated BMD (eBMD), in ~1.2 million individuals. We then identified target genes enriched for genes known to influence bone density and strength (maximum odds ratio (OR) = 58, P = 1 × 10-75) from cell-specific features, including chromatin conformation and accessible chromatin sites. We next performed rapid-throughput skeletal phenotyping of 126 knockout mice with disruptions in predicted target genes and found an increased abnormal skeletal phenotype frequency compared to 526 unselected lines (P < 0.0001). In-depth analysis of one gene, DAAM2, showed a disproportionate decrease in bone strength relative to mineralization. This genetic atlas provides evidence linking associated SNPs to causal genes, offers new insight into osteoporosis pathophysiology, and highlights opportunities for drug development.
Bone Density/genetics , Genetic Predisposition to Disease/genetics , Osteoporosis/genetics , Adult , Aged , Animals , Female , Fractures, Bone/genetics , Genome-Wide Association Study/methods , Humans , Male , Mice , Mice, Knockout , Middle Aged , Phenotype , Polymorphism, Single Nucleotide/genetics
Levothyroxine (LT4) is a form of thyroid hormone used to treat hypothyroidism. In the brain, T4 is converted to the active form T3 by type 2 deiodinase (D2). Thus, it is intriguing that carriers of the Thr92Ala polymorphism in the D2 gene (DIO2) exhibit clinical improvement when liothyronine (LT3) is added to LT4 therapy. Here, we report that D2 is a cargo protein in ER Golgi intermediary compartment (ERGIC) vesicles, recycling between ER and Golgi. The Thr92-to-Ala substitution (Ala92-D2) caused ER stress and activated the unfolded protein response (UPR). Ala92-D2 accumulated in the trans-Golgi and generated less T3, which was restored by eliminating ER stress with the chemical chaperone 4-phenyl butyric acid (4-PBA). An Ala92-Dio2 polymorphism-carrying mouse exhibited UPR and hypothyroidism in distinct brain areas. The mouse refrained from physical activity, slept more, and required additional time to memorize objects. Enhancing T3 signaling in the brain with LT3 improved cognition, whereas restoring proteostasis with 4-PBA eliminated the Ala92-Dio2 phenotype. In contrast, primary hypothyroidism intensified the Ala92-Dio2 phenotype, with only partial response to LT4 therapy. Disruption of cellular proteostasis and reduced Ala92-D2 activity may explain the failure of LT4 therapy in carriers of Thr92Ala-DIO2.
Brain , Endoplasmic Reticulum Stress , Hypothyroidism , Iodide Peroxidase , Polymorphism, Genetic , Unfolded Protein Response , Amino Acid Substitution , Animals , Brain/enzymology , Brain/pathology , Endoplasmic Reticulum/enzymology , Endoplasmic Reticulum/genetics , Golgi Apparatus/enzymology , Golgi Apparatus/genetics , HEK293 Cells , Humans , Hypothyroidism/drug therapy , Hypothyroidism/enzymology , Hypothyroidism/genetics , Hypothyroidism/pathology , Iodide Peroxidase/genetics , Iodide Peroxidase/metabolism , Mice , Mice, Transgenic , Mutation, Missense , Thyroxine/therapeutic use , Triiodothyronine/therapeutic use , Iodothyronine Deiodinase Type II
Osteoporosis is a common disease diagnosed primarily by measurement of bone mineral density (BMD). We undertook a genome-wide association study (GWAS) in 142,487 individuals from the UK Biobank to identify loci associated with BMD as estimated by quantitative ultrasound of the heel. We identified 307 conditionally independent single-nucleotide polymorphisms (SNPs) that attained genome-wide significance at 203 loci, explaining approximately 12% of the phenotypic variance. These included 153 previously unreported loci, and several rare variants with large effect sizes. To investigate the underlying mechanisms, we undertook (1) bioinformatic, functional genomic annotation and human osteoblast expression studies; (2) gene-function prediction; (3) skeletal phenotyping of 120 knockout mice with deletions of genes adjacent to lead independent SNPs; and (4) analysis of gene expression in mouse osteoblasts, osteocytes and osteoclasts. The results implicate GPC6 as a novel determinant of BMD, and also identify abnormal skeletal phenotypes in knockout mice associated with a further 100 prioritized genes.
Bone Density/genetics , Calcaneus/pathology , Genome-Wide Association Study , Osteoporosis/genetics , Polymorphism, Single Nucleotide , Animals , Disease Models, Animal , Female , Femur/chemistry , Gene Expression Profiling , Glypicans/deficiency , Glypicans/genetics , Glypicans/physiology , Growth Disorders/genetics , Humans , Male , Mice , Mice, Knockout , Molecular Sequence Annotation , Osteoblasts/metabolism , Osteochondrodysplasias/congenital , Osteochondrodysplasias/genetics , Osteoclasts/metabolism , Osteocytes/metabolism , Osteoporosis/pathology , Phenotype
