A novel mutation in MYCN gene causing congenital absence of the flexor pollicis longus tendon as an unusual presentation of Feingold syndrome 1.

Feingold syndrome 1 (FGLDS1) is an autosomal dominant malformation syndrome, characterized by skeletal anomalies, microcephaly, facial dysmorphism, gastrointestinal atresias and learning disabilities. Mutations in the MYCN gene are known to be the cause of this syndrome. Congenital absence of the flexor pollicis longus (CAFPL) tendon is a rare hand anomaly. Most cases are sporadic and no genetic variants have been described associated with this abnormality. We describe here a pedigree combining familial CAFPL tendon as a feature of FGLDS1. Molecular analyses of whole exome sequence data in five affected family members spanning three generations of this family revealed a novel mutation in the MYCN gene (c.1171C>T; p.Arg391Cys). Variants in MYCN have not been published in association with isolated or syndromic CAFPL tendon, nor has this been described as a skeletal feature of Feingold syndrome. This report expands on the clinical and molecular spectrum of MYCN-related disorders and highlights the importance of MYCN protein in normal human thumb and foramen development.

CPT1A methylation is associated with plasma adiponectin.

BACKGROUND AND AIMS: Adiponectin, an adipose-secreted protein that has been linked to insulin sensitivity, plasma lipids, and inflammatory patterns, is an established biomarker for metabolic health. Despite clinical relevance and high heritability, the determinants of plasma adiponectin levels remain poorly understood. METHODS AND RESULTS: We conducted the first epigenome-wide cross-sectional study of adiponectin levels using methylation data on 368,051 cytosine-phosphate-guanine (CpG) sites in CD4+ T-cells from the Genetics of Lipid Lowering Drugs and Diet Network (GOLDN, n = 991). We fit linear mixed models, adjusting for age, sex, study site, T-cell purity, and family. We have identified a positive association (regression coefficient ± SE = 0.01 ± 0.001, P = 3.4 × 10-13) between plasma adiponectin levels and methylation of a CpG site in CPT1A, a key player in fatty acid metabolism. The association was replicated (n = 474, P = 0.0009) in whole blood samples from the Amish participants of the Heredity and Phenotype Intervention (HAPI) Heart Study as well as White (n = 592, P = 0.0005) but not Black (n = 243, P = 0.18) participants of the Bogalusa Heart Study (BHS). The association remained significant upon adjusting for BMI and smoking in GOLDN and HAPI but not BHS. We also identified associations between methylation loci in RNF145 and UFM1 and plasma adiponectin in GOLDN and White BHS participants, although the association was not robust to adjustment for BMI or smoking. CONCLUSION: We have identified and replicated associations between several biologically plausible loci and plasma adiponectin. These findings support the importance of epigenetic processes in metabolic traits, laying the groundwork for future translational applications.

Purine pathway implicated in mechanism of resistance to aspirin therapy: pharmacometabolomics-informed pharmacogenomics.

Although aspirin is a well-established antiplatelet agent, the mechanisms of aspirin resistance remain poorly understood. Metabolomics allows for measurement of hundreds of small molecules in biological samples, enabling detailed mapping of pathways involved in drug response. We defined the metabolic signature of aspirin exposure in subjects from the Heredity and Phenotype Intervention Heart Study. Many metabolites, including known aspirin catabolites, changed on exposure to aspirin, and pathway enrichment analysis identified purine metabolism as significantly affected by drug exposure. Furthermore, purines were associated with aspirin response, and poor responders had higher postaspirin adenosine and inosine levels than did good responders (n = 76; both P < 4 × 10(-3)). Using our established "pharmacometabolomics-informed pharmacogenomics" approach, we identified genetic variants in adenosine kinase associated with aspirin response. Combining metabolomics and genomics allowed for more comprehensive interrogation of mechanisms of variation in aspirin response--an important step toward personalized treatment approaches for cardiovascular disease.

The CYP2C19*17 variant is not independently associated with clopidogrel response.

BACKGROUND: Cytochrome P450 2C19 (CYP2C19) is the principal enzyme responsible for converting clopidogrel into its active metabolite, and common genetic variants have been identified, most notably CYP2C19*2 and CYP2C19*17, that are believed to alter its activity and expression, respectively. OBJECTIVE: We evaluated whether the consequences of the CYP2C19*2 and CYP2C19*17 variants on clopidogrel response were independent of each other or genetically linked through linkage disequilibrium (LD). PATIENTS/METHODS: We genotyped the CYP2C19*2 and CYP2C19*17 variants in 621 members of the Pharmacogenomics of Anti-Platelet Intervention (PAPI) Study and evaluated the effects of these polymorphisms singly and then jointly, taking into account LD, on clopidogrel prodrug level, clopidogrel active metabolite level, and adenosine 5'-diphosphate (ADP)-stimulated platelet aggregation before and after clopidogrel exposure. RESULTS: The CYP2C19*2 and CYP2C19*17 variants were in LD (|D'| = 1.0; r(2)  = 0.07). In association analyses that did and did not account for the effects of CYP2C19*17, CYP2C19*2 was strongly associated with levels of clopidogrel active metabolite (ß = -5.24, P = 3.0 × 10(-9) and ß = -5.36, P = 3.3 × 10(-14) , respectively) and posttreatment ADP-stimulated platelet aggregation (ß = 7.55, P = 2.9 × 10(-16) and ß = 7.51, P = 7.0 × 10(-15) , respectively). In contrast, CYP2C19*17 was marginally associated with clopidogrel active metabolite levels and ADP-stimulated platelet aggregation before (ß = 1.57, P = 0.04 and ß = -1.98, P = 0.01, respectively) but not after (ß = 0.40, P = 0.59 and ß = -0.13, P = 0.69, respectively) adjustment for the CYP2C19*2 variant. Stratified analyses of CYP2C19*2/CYP2C19*17 genotype combinations revealed that CYP2C19*2, and not CYP2C19*17, was the primary determinant in altering clopidogrel response. CONCLUSIONS: Our results suggest that CYP2C19*17 has a small (if any) effect on clopidogrel-related traits and that the observed effect of this variant is due to LD with the CYP2C19*2 loss-of-function variant.

The effect of elinogrel on high platelet reactivity during dual antiplatelet therapy and the relation to CYP2C19*2 genotype: first experience in patients.

UNLABELLED: To study the effect of a new direct acting reversible P2Y(12) inhibitor, elinogrel (PRT060128), and the relation to cytochrome P450 (CYP) polymorphisms in patients with high platelet reactivity (HPR) on standard dual antiplatelet therapy. METHODS AND RESULTS: We studied the pharmacodynamic and pharmacokinetic effects of a single 60-mg oral dose of elinogrel in 20 of 45 previously stented stable patients with HPR. We also genotyped for CYP2C19*2,3,5,17 and CYP3A5*3. Platelet reactivity fell within 4 h of dosing, the earliest time point evaluated as measured by the following assays: maximum 5 and 10 microM ADP LTA (P < 0.001 for both vs. predosing); maximum 20 microM ADP LTA (P < 0.05); VerifyNow (P < 0.001); thrombelastography (P < 0.05); VASP phosphorylation (P < 0.01); and perfusion chamber assay (P < 0.05); this was reversible within 24 h in these same assays (P = ns vs. predosing for all assays). CYP2C19*2 was present in 44% of all patients but was more frequent in HPR patients (77% vs. 16%, P = 0.0004). CONCLUSIONS: HPR is reversibly overcome by a single 60-mg oral dose of elinogrel, a drug now being investigated in a phase 2 trial. CYP2C19*2 was associated with HPR during conventional dual antiplatelet therapy.

Relationship between vascular calcification and bone mineral density in the Old-order Amish.

Vascular calcification and osteoporosis are common age-related processes that are influenced by both genetic and nongenetic factors. Whether common genes underlie these processes is not known. We measured coronary artery calcification (CAC), aortic calcification (AC), and bone mineral density (BMD) in 682 men and women from large Old-Order Amish families. We assessed the heritabilities of these traits and then evaluated, using variance decomposition procedures, whether variation in the traits was influenced by a common set of genes (i.e., pleiotropy). Significant heritabilities were detected for BMD of the femoral neck and spine (0.65, 0.63) and CAC and AC (0.43, 0.42). Mean BMD did not differ significantly across quartiles of either CAC or AC in either sex. In neither the total group nor any single subgroup (men, women, postmenopausal women) did any of the genetic or environmental correlations between BMD and vascular calcification achieve statistical significance. However, subjects with a history of cardiovascular disease (CVD) events had significantly lower BMD at the femoral neck compared to subjects who reported no prior history of CVD (age-, sex-, body mass index-, and family structure-adjusted P = 0.003). We detected no evidence for shared genes affecting the joint distribution of bone and vascular calcification. However, our results do reveal a lower BMD in subjects with a prior history of CVD in the Old-Order Amish.

The pharmacogenetics research network: from SNP discovery to clinical drug response.

The NIH Pharmacogenetics Research Network (PGRN) is a collaborative group of investigators with a wide range of research interests, but all attempting to correlate drug response with genetic variation. Several research groups concentrate on drugs used to treat specific medical disorders (asthma, depression, cardiovascular disease, addiction of nicotine, and cancer), whereas others are focused on specific groups of proteins that interact with drugs (membrane transporters and phase II drug-metabolizing enzymes). The diverse scientific information is stored and annotated in a publicly accessible knowledge base, the Pharmacogenetics and Pharmacogenomics Knowledge base (PharmGKB). This report highlights selected achievements and scientific approaches as well as hypotheses about future directions of each of the groups within the PGRN. Seven major topics are included: informatics (PharmGKB), cardiovascular, pulmonary, addiction, cancer, transport, and metabolism.

FABP2 genotype is associated with insulin sensitivity in older women.

This study determined whether sequence variations in genes related to glucose and insulin metabolism are associated with insulin sensitivity in postmenopausal women after accounting for habitual physical activity levels, body composition, and hormone-replacement therapy (HRT). Eighteen sedentary, 19 physically active, and 23 athletic postmenopausal white women underwent a frequently sampled intravenous glucose tolerance test to determine insulin sensitivity (S(I)) and dual-energy x-ray absorptiometry to determine body composition. After accounting for the effects of body composition, habitual physical activity levels, and HRT status, S(I) was 26% lower in subjects with the Thr54 fatty acid-binding protein 2 (FABP2) allele compared with Ala54 homozygotes (4.3 +/- 0.5 v 5.8 +/- 0.6 microU x 10(-4)/min/mL; P <.05). Angiotensin-converting enzyme genotype was not significantly associated with S(I). There were no significant associations between Gln27Glu beta(2)-adrenergic receptor or Pro12Ala peroxisome proliferator-activated receptor gamma variants and glucose or insulin kinetic parameters. It was concluded that FABP2 genotype influences insulin sensitivity independent of body composition, habitual physical activity levels, and HRT status in postmenopausal white women.

Pancreatic reg gene expression is inhibited during cellular differentiation.

BACKGROUND AND OBJECTIVE: Factors that control pancreatic regenerating (reg I) gene expression are unknown, but it is believed that its expression may correspond with cellular differentiation. The authors recently demonstrated that reg I is expressed in AR42J, a rat acinar cell line whose state of differentiation can be modulated by dexamethasone. They used this line to study reg I expression during cellular proliferation and differentiation. METHODS: After treatment of cells with 10 nmol/L dexamethasone, proliferation was assayed by thymidine incorporation; differentiation by expression of elastase I mRNA. Reg I mRNA levels were measured using a rat reg I cDNA probe, and reg I protein levels assayed by enzyme-linked immunosorbent assay of cellular lysates with a polyclonal antibody. The effect of gastrin, cholecystokinin and glucagon on reg I expression was also studied. RESULTS: When compared with controls, treatment with dexamethasone caused thymidine incorporation to decrease and elastase mRNA levels to increase. Reg I mRNA decreased from controls of 100 +/- 16% to 40 +/- 18% (p < 0.05), and reg I protein levels decreased as well. Gastrointestinal hormones had no significant effect on either elastase or reg I gene expression. CONCLUSIONS: Expression of reg I inversely correlates with the level of cellular differentiation, can be modulated via the glucocorticoid receptor, and is a potential marker of gastrointestinal epithelial differentiation. Despite its presence within a pancreatic acinar cell line, reg I gene expression is not modulated by gastrointestinal hormones.

Pancreatic regeneration (reg) gene expression in a rat model of islet hyperplasia.

BACKGROUND: After pancreatectomy, regeneration of acinar and islet elements occurs. Recent data from a model of islet hyperplasia in the hamster suggested that induction of a local pancreatic factor stimulates islet formation. We postulate that the reg gene may be this factor. METHODS: We studied reg expression during induction of islet growth by using a similar model in the rat. Rats underwent surgical wrapping of the splenic lobe of the pancreas or sham operation. RESULTS: At 2 days ductular proliferation and immunohistochemical evidence of insulin within ductular epithelia were evident in the wrapped lobe. By 14 and 56 days islet number per square millimeter increased 63% and 43%, respectively. Reg mRNA levels, measured by Northern blot analysis with a rat reg cDNA probe (n = 5), increased 300% at 2 days in the wrapped lobe and decreased to that of unwrapped controls by 14 days. In situ hybridization showed localization of reg to the acinar cells. In unwrapped gastric lobes of animals who underwent surgical wrapping of the splenic lobe, no change in islet number per square millimeter or reg gene expression was noted. CONCLUSIONS: Surgical wrapping of the pancreatic splenic lobe induces local reg gene expression that is temporally associated with duct cell hyperplasia. This is followed by islet formation within the wrapped lobe. Reg may play a role in the induction of new islets from ductular precursors and in maintenance of normal islet function.

Xenopus laevis oocytes, eggs and tadpoles contain immunoactive insulin.

Insulin is a multifunctional polypeptide hormone that regulates metabolic processes and promotes mitogenesis and differentiation in vitro in the cells and tissues of several species. Its role in vivo during embryogenesis is still poorly understood. We have previously found insulin mRNA in mature Xenopus laevis oocytes and in embryos during neurulation (before organogenesis of the pancreas takes place). We have now measured insulin immunoactivity in mature oocytes, unfertilized eggs and day-2 tadpoles. Using reversed phase high performance liquid chromatography, we found low levels of insulin in extracts of oocytes (stage VI). Both Xenopus insulin I and II were detected in unfertilized eggs. The day-2 tadpoles (stages 31-33) also contained immunoactive insulin, and in swimming tadpoles (stage 46) a few clusters of cells containing insulin immunoactivity could be identified by indirect immunofluorescence. Immunoblot analysis was relatively insensitive, detecting insulin only in the adult Xenopus pancreas. In summary, insulin (from maternal origin and embryonic expression) appears to be present early enough in Xenopus laevis to influence developmental processes such as neurulation.