Diagnosis And Treatment Of Hypertrophic Osteoarthropathy And Mendelian Randomization Study Between 25OHD And Bone Metabolism

PART ONE Clinical,Biochemical and Genetic Features of 41 Han Chinese Families with Primary Hypertrophic Osteoarthropathy,and Their Therapeutic Response to EtoricoxibBackgrounds: Primary hypertrophic osteoarthropathy(PHO)is a rare inherited disease caused by genetic defects in prostaglandin metabolism pathway;disturbed prostaglandin E2(PGE2)catabolism resulting in increased PGE2 levels is suggested in the pathogenesis.We aim to characterize the genetic,clinical and biochemical features of PHO patients,and to conduct a clinical intervention.Methods: We enrolled forty-one PHO probands and their family members,and carefully collected the medical history.Fasting blood and urinary samples were collected for biochemical detection,and genomic DNA were extracted for identification of disease-causing gene.We screened eligible PHO patients for a six months clinical intervention of a selective cyclooxygenase-2 inhibitor(i.e.,Etoricoxib,60 mg/day)based on estabolished criteria,and conducted follow-ups every three months to analyze therapeutic response.Results: Forty-three Han Chinese subjects were genetically diagnosed with PHO.Mutations in HPGD gene,causing hypertrophic osteoarthropathy,primary,autosomal recessive 1(PHOAR1,OMIM 259100),were identified in 7 patients,and mutations in SLCO2A1 gene,causing hypertrophic osteoarthropathy,primary,autosomal recessive 2(PHOAR2,OMIM 614441),were identified in 36 patients.Clinical phenotypes of PHO varied,ranging from mild isolated clubbing finger to severe pachydermia and disabling joint swelling,even within families.Circulating PGE2 metabolism features of PHOAR2 were different from those of PHOAR1.Different frequency and severity of pachydermia between the subgroups were also indicated.A percentage of PHOAR2 patients suffered from gastrointestinal hemorrhage,but this symptom was not observed in PHOAR1 subgroup.Clinical evidence highlighted essential role of sex hormones in prostaglandin transporter regulation,although no significant associations of urinary PGE2 or PGE-M with sex hormones were identified.Treatment with Etoricoxib was proved to be beneficial and safe.We detected its notable efficacy in decreasing urinary PGE2 levels in the majority of the enrolled patients during 6 months of intervention;assessed clinical phenotypes,including pachydermia,clubbing finger and joint swelling,were improved.We found no visible evidence of positive effect of Etoricoxib on periostosis.But significant links between urinary PGE2 and serum bone turnover markers indicated potential role of decreased PGE2 in periostosis management.Conclusions: This is the largest reported cohort of subjects genetically diagnosed with PHO.For the first time,we systematically investigate the biochemical and clinical differences between PHOAR1 and PHOAR2,providing potential clubs in functional researches of PGT and 15-PGDH.Meanwhile,we prospectively demonstrated the positive efficacy and safety of Etoricoxib for PHO patients,which would provide a basis of estabolishment of treatment strategy for the disease.PART TWO Vitamin D Levels,Bone Mineral Density,and Bone Metabolism Related Markers: a Mendelian Randomisation StudyBackgounds: Vitamin D deficiency is associated with osteoporosis and osteoprosic fracture,but it is controversial whether the associations are causal.Our study aims to test the causal associations between serum 25-hydroxyvitamin D(25OHD)and bone mineral density(BMD)and bone metabolism related markers using Mendelian randomization(MR)analysis.Methods: We enrolled 1,824 Shanghai Han postmenopausal women in present study.Serum levels of 25 OHD,parathyroid hormone(PTH)and bone turnover markers including procollagen type 1 N-terminal propeptide(P1NP)and Beta-Cross Laps of type 1 collagen containing cross-linked C-telopeptide(Beta-CTX)were detected with electrochemiluminescence.Enzyme linked immunosorbent assay was used to measure serum levels of vitamin D binding protein(DBP),and serum bioavailable and free 25 OHD levels were then calculated.BMD values were meaused using double energy X-ray absorption methods.Meanwhile,genomic DNA were extracted from peripheral blood of each subject and were used for gaining genotyping data of single nucleotide polymorphisms(SNP)in vitamin D metabolism related genes including GC-s4588,GC-rs7041,GC-rs2282679,GC-rs1155563,NADSYN1-rs2276360,NADSYN1-rs12785878,CYP2R1-rs2060793,CYP2R1-rs10741657,CYP2R1-rs10766197,and CYP24A1-rs6013897.We conducted Pearson correlation analysis and Odinary least squares(OLS)regression models to examine the associations between serum 25 OHD levels and BMD and bone metabolism related markers.And then seleted eligible SNP as instrumental variables(IVs)based on MR analysis assumptions.Different two-stage least squares(TSLS)were constructed with these IVs and were used to test the associations among genetically low serum 25 OHD levels with BMD and bone metabolism related markers.Results: Serum 25 OHD levels were adjusted for age,season and BMI for subsequent analysis.OLS regression models showed that the serum levels of 25 OHD were positively associated with BMD at lumber 1-4(P = 0.003),neck(P = 0.006),and total hip(P = 0.005),and were inversely associated with serum levels of PTH(P = 8.18E-09)and P1NP(P = 0.020).However,no significant associations were identified among serum levels of bioavailable or free 25 OHD with any clinical outcomes tested(all P > 0.05).TSLS models including single instrumental variable models,and unweighted and weighted multiple instrumental variables models were constructed based on selected SNP including GC-rs2282679,NADSYN1-rs12785878,CYP2R1-rs10741657,and CYP24A1-rs6013897.Nevertheless,none of the TSLS models provided evidence for associations between genetically low serum 25 OHD and BMD and bone metabolism related markers(all P > 0.05).Conclusions: This study suggest that after controlling for unidentified confounding factors in MR analyses,the associations between serum 25OHD and BMD and bone metabolism related markers are unlikely to be causal in Shanghai postmenopausal women.However,our study had a limited ability to exclude very small effects,and further investigation in a larger study population may be required.