Ankylosing spondylitis in West Africans--evidence for a non-HLA-B27 protective effect

OBJECTIVE

To determine the prevalence of ankylosing spondylitis in the Fula ethnic group in The Gambia, and relate the disease prevalence to the B27 frequency and subtype distribution of that population.

METHODS

215 first degree relatives of 48 B27 positive Fula twin pairs, and 900 adult Fula males were screened for ankylosing spondylitis by clinical and, where appropriate, radiographic means. The B27 prevalence was determined by PCR/sequence specific oligonucleotides on finger prick samples from 100 unrelated Fula, and B27 subtype distribution by SSCP on unrelated B27 positive individuals. This data were then compared with the prevalence of ankylosing spondylitis among B27 positive Caucasians.

RESULTS

No case of ankylosing spondylitis was seen. Six per cent of Fula are B27 positive, of which 32% are B*2703 and 68% B*2705. Assuming the penetrance of ankylosing spondylitis in B27 positive Fula is the same as in B27 positive Caucasians, the probability of not observing any cases of ankylosing spondylitis among the Fula examined is remote (P = 6.7 x 10(-6)). Similarly, the chance of not seeing any cases among those expected to be either B*2705 or B*2703 was small (P = 3.2 x 10(-4) for B*2705, and P = 0.02 for B*2703).

CONCLUSIONS

The risk of developing ankylosing spondylitis in B27 positive Fula is lower than in B27 positive Caucasians. This is not explained by the B27 subtype distribution among Fula, and suggests the presence of some non-B27 protective factor reducing the prevalence of ankylosing spondylitis in this population.

Three-dimensional measurement method of arthritic glenoid cavity morphology: feasibility and reproducibility

INTRODUCTION

Glenoid component loosening is the main complication of total shoulder arthroplasty. Better knowledge of the arthritic glenoid cavity anatomy can help in developing new implants and techniques. The goal of this study was to describe and validate the reproducibility of a CT scan-based, 3D measurement method used to describe various parameters characterizing arthritic glenoid cavity morphology.

MATERIALS AND METHODS

Twelve CT scans and 29 CT arthrogram were evaluated. These scans were taken from 41 patients with glenohumeral osteoarthritis who received an anatomical shoulder prosthesis. A 3D reconstruction of the scapula was performed based on the DICOM files. Following the 3D volume acquisition, points on the glenoid articular surface were manually extracted by three observers, each one three times, allowing one week between readings, to determine the inter- and intra-observer reproducibility. The intraclass correlation coefficient (ICC) was calculated on five 3D parameters that were automatically calculated: glenoïd height, glenoid width, height at maximum width glenoid version and radius of the articular surface best-fit sphere.

RESULTS

The intra-observer and inter-observer ICC were 0.91 to 0.99, and 0.95 to 0.99, respectively.

DISCUSSION

This study is the first to report on a reproducible 3D measurement method, based on CT scans, for the arthritic glenoid cavity, which derives the joint radius of curvature among other morphology parameters. These 3D measurements are advantageous because they are free of problems related to patient positioning in the CT scanner and to the choice of slices, which limits the accuracy of measurements made on slices from 2D CT scans. Three-dimensional methodology similar to ours has been validated on healthy glenoids.

CONCLUSION

This study confirms the reliability and good reproducibility of our method, which allows us to extend this method to a larger patient cohort and adapt this automated technology to preoperative planning software.

A comparison of patients with relapsed and chemo-refractory gestational trophoblastic neoplasia

The majority of women requiring chemotherapy for gestational trophoblastic disease (GTN) are cured with their initial chemotherapy treatment. However, a small percentage either become refractory to treatment, or relapse after the completion of treatment. This study investigates the characteristics and outcome of these patients. Patients were identified from the Charing Cross Hospital GTD database. The outcome of these patients with relapsed disease was compared to those with refractory disease. Between 1980 and 2004, 1708 patients were treated with chemotherapy for GTN. Sixty (3.5%) patents relapsed following completion of initial therapy. The overall 5-year survival for patients with relapsed GTN was 93% (95% CI 86-100%). The overall survival for patients with low-risk and high-risk disease at presentation, who subsequently relapsed was 100% (n=35), and 84% (n=25) (95% CI: 66-96%: P<0.05), respectively. Eleven patients were identified who failed to enter remission and had refractory disease. These patients had a worse outcome compared to patients with relapsed disease (5-year survival 43% (95% CI:12-73% P<0.01)). The outcome of patients with relapsed GTN is good. However, patients with primary chemo-refractory disease do poorly and novel therapies are required for this group of patients.

Management of early melanoma recurrence despite adjuvant anti-PD-1 antibody therapy☆

BACKGROUND

Anti-programmed cell death protein 1 (PD-1) antibodies (PD1) prolong recurrence-free survival in high-risk resected melanoma; however, approximately 25%-30% of patients recur within 1 year. This study describes the pattern of recurrence, management and outcomes of patients who recur with adjuvant PD1 therapy.

PATIENTS AND METHODS

Consecutive patients from 16 centres who recurred having received adjuvant PD1 therapy for resected stage III/IV melanoma were studied. Recurrence characteristics, management and outcomes were examined; patients with mucosal melanoma were analysed separately.

RESULTS

Melanoma recurrence occurred in 147 (17%) of ∼850 patients treated with adjuvant PD1. In those with cutaneous melanoma (n = 136), median time to recurrence was 4.6 months (range 0.3-35.7); 104 (76%) recurred during (ON) adjuvant PD1 after a median 3.2 months and 32 (24%) following (OFF) treatment cessation after a median 12.5 months, including in 21 (15%) who ceased early for toxicity. Fifty-nine (43%) recurred with locoregional disease only and 77 (57%) with distant disease. Of those who recurred locally, 22/59 (37%) subsequently recurred distantly. Eighty-nine (65%) patients received systemic therapy after recurrence. Of those who recurred ON adjuvant PD1, none (0/6) responded to PD1 alone; 8/33 assessable patients (24%) responded to ipilimumab (alone or in combination with PD1) and 18/23 (78%) responded to BRAF/MEK inhibitors. Of those who recurred OFF adjuvant PD1, two out of five (40%) responded to PD1 monotherapy, two out of five (40%) responded to ipilimumab-based therapy and 9/10 (90%) responded to BRAF/MEK inhibitors.

CONCLUSIONS

Most patients who recur early despite adjuvant PD1 develop distant metastases. In those who recur ON adjuvant PD1, there is minimal activity of further PD1 monotherapy, but ipilimumab (alone or in combination with PD1) and BRAF/MEK inhibitors have clinical utility. Retreatment with PD1 may have activity in select patients who recur OFF PD1.

Recipient outcomes for expanded criteria living kidney donors: the disconnect between current evidence and practice

Older individuals or those with medical complexities are undergoing living donor nephrectomy more than ever before. Transplant outcomes for recipients of kidneys from these living expanded criteria donors are largely uncertain. We systematically reviewed studies from 1980 to June 2008 that described transplant outcomes for recipients of kidneys from expanded criteria living donors. Results were organized by the following criteria: older age, obesity, hypertension, reduced glomerular filtration rate (GFR), proteinuria and hematuria. Pairs of reviewers independently evaluated each citation and abstracted data on study and donor characteristics, recipient survival, graft survival, serum creatinine and GFR. Transplant outcomes for recipients of kidneys from older donors (> or =60 years) were described in 31 studies. Recipients of kidneys from older donors had poorer 5-year patient and graft survival than recipients of kidneys from younger donors [meta-analysis of 12 studies, 72% vs. 80%, unadjusted relative risk (RR) of survival 0.89, 95% confidence interval (CI) 0.83-0.95]. In meta-regression, this association diminished over time (1980s RR 0.79, 95% CI 0.65-0.96 vs. 1990s RR 0.91, 95% CI 0.85-0.99). Few transplant outcomes were described for other expanded criteria. This disconnect between donor selection and a lack of knowledge of recipient outcomes should give transplant decision-makers pause and sets an agenda for future research.

Dysbiotic salivary microbiota in dry mouth and primary Sjögren's syndrome patients

Objectives

Primary Sjögren’s syndrome (pSS) is an autoimmune disease characterized by reduced lacrimal and salivary secretion. Sicca symptoms together with fatigue and musculoskeletal pain can significantly reduce the patients’ quality of life. Furthermore, low salivary secretion may disrupt the oral microbial homeostasis. The aim of this study was to compare the salivary microbiota from pSS patients with patients with sicca symptoms not fulfilling the classification criteria for pSS (non-SS), and with healthy controls without sicca complaints.

Methods

Pellets from centrifuged chewing-stimulated whole saliva from pSS patients (n = 15), non-SS sicca patients (n = 15) and healthy controls (n = 15) were prepared. DNA was extracted and analyzed by 16S rRNA gene sequencing. The acquired sequencing data were performed using the human oral microbiome database (HOMD).

Results

We detected 42, 45, and 34 bacterial genera in saliva samples from pSS patients, non-SS sicca patients, and healthy controls, respectively. The most abundant genera in all samples were Prevotella, Veillonella, Streptococcus, and Haemophilus. At species level Streptococcus intermedius, Prevotella intermedia, Fusobacterium nucleatum subsp. vincentii, Porphyromonas endodontalis, Prevotella nancensis, Tannerella spp., and Treponema spp. were detected in the samples from pSS and non-SS only, while Porphyromonas pasteri was mostly found among the healthy controls.

Conclusion

Our study indicated dysbiosis in the salivary microbiota from pSS and non-SS patients compared to healthy controls. Additionally, the results showed that the salivary microbiome in the pSS group differed significantly from the non-SS group.

Reflex actions of knee joint afferents during contraction of the human quadriceps

(1) The spinal reflex actions of afferents stimulated by knee joint distension have been investigated in man. (2) Cannulation of the knee and infusion of saline raised intra-articular pressure, especially during quadriceps contraction. High pressures did not induce any sensation of pain. Pressure was taken as an index of joint proprioceptor activation. (3) Increased pressure progressively depressed the quadriceps H-reflex, both at rest and during quadriceps contraction. There was no indication of a threshold pressure for this inhibitory action. (4) It is concluded that joint distension inhibits quadriceps motoneurons through spinal pathways that still operate during voluntary contraction. These pathways could thus contribute to pathological weakness after joint injury. (5) Joint distension produced spatial facilitation of non-reciprocal inhibition of quadriceps H-reflexes from afferents in the tibial nerve.

Applied physiology of strength and power in old age

The loss of strength and power in old age has important implications for health. Even with healthy elderly people, cross-sectional comparisons imply a loss of strength at some 1.5% per year and of power at some 3.5% per year (averaged across the age range 65 to 84). On the other hand, healthy, very elderly people are at least as responsive to strength-training as younger adults. It is important to establish whether elderly people derive functional benefit from training-induced improvements in strength and whether laboratory measurements of strength and power might be used to identify those elderly people most at risk of losing important, everyday functional abilities.

Evidence for an association between rheumatoid arthritis and autoimmune endocrine disease

Evidence is presented for the first time of a significantly increased prevalence of type 1 (insulin-dependent) diabetes in the close relatives of patients with rheumatoid arthritis. Thirty-nine (13%) of 295 patients with classical or definite rheumatoid arthritis had a first or second degree relative with type 1 diabetes and 38 (13%) had a close relative with autoimmune thyroid disease. These findings could be compatible with a possible common genetically determined mechanism of susceptibility to both diseases.

Ageing and physiological functions

In youth, most physiological functions have generous spare capacity. Even in health, however, increasing age is characterized by progressive erosion of these 'safety margins'. Examples include the decline of bone mass (towards a threshold for likelihood of fracture), of glomerular filtration rate (towards a threshold for susceptibility to clinical renal failure), of renal tubular function (towards a threshold for clinically important susceptibility to dehydration), of hepatic function (towards a threshold for accumulation following conventional 'young adult' doses of common medications), or of lower limb explosive power (towards thresholds for impaired functional mobility). Increasing age is also characterized by a rising prevalence of chronic pathologies, complicating attempts to determine the rate or the mechanism of the age-related decline in a physiological function. Nevertheless, it is clear that in many organs the loss of function is largely attributable to the loss of functioning cells, even in the absence of overt disease. This apparently fundamental aspect of ageing remains poorly understood.

Screening for diabetes in general practice: cross sectional population study

OBJECTIVE

To assess the policy proposed by the American Diabetes Association of universal screening in general practice of all patients aged over 45 years for diabetes.

DESIGN

Cross sectional population study.

SETTING

Local general practice in the United Kingdom.

PARTICIPANTS

All patients aged over 45 not known to have diabetes.

MAIN OUTCOME MEASURES

Prevalence of diabetes in the screened population, cardiovascular risk profile of patients diagnosed as having diabetes after screening.

RESULTS

Of 2481 patients aged over 45 and not known to have diabetes, 876 attended for screening. There were no significant demographic differences between the screened and unscreened patients. Prevalence of diabetes in patients with age as a sole risk factor was 0.2% (95% confidence interval 0% to 1.4%). Prevalence of diabetes in patients with age and one or more other risk factors (hypertension, obesity, or a family history of diabetes) was 2.8% (1.6% to 4.7%). Four hours a week for a year would be needed to screen all people over 45 in the practice's population; about half this time would be needed to screen patients with risk factors other than age. More than 80% of patients newly diagnosed as having diabetes had a 10 year risk of coronary heart disease >15%, 73% (45% to 92%) were hypertensive, and 73% (45% to 92%) had a cholesterol concentration >5 mmol/l.

CONCLUSIONS

Screening for diabetes in general practice by measuring fasting blood glucose is feasible but has a very low yield in patients whose sole risk factor for diabetes is age over 45. Screening in a low risk population would best be targeted at patients with multiple risk factors.

Prospective study of the radiological changes in hands, feet, and cervical spine in adult rheumatoid disease

Annual radiographs of hands, feet, and cervical spine were taken in 100 patients with rheumatoid arthritis from the first year of disease for a mean follow-up period of 9.5 years. Seventy-six patients developed peripheral erosive disease and 54 developed rheumatoid changes of the cervical spine, of whom 34 (63%) had subluxations. The severity of rheumatoid neck damage correlated strongly with the severity of peripheral erosive disease (p = 0.002). Cervical subluxation was more likely to occur in patients with erosions of the hands and feet which deteriorated progressively with time (p = 0.018). The timing and severity of cervical subluxation coincided with the progression of peripheral erosive disease in 26 of these 34 patients (76.5%). The other 8 patients with cervical subluxation (23.5%) had none or only mild peripheral erosions, but their subluxations did not progress with time. There were 9 patients with marked cervical subluxations which deteriorated relentlessly, and they all also had severe progressive erosive disease of the hands and feet. One of these patients developed a cervical myelopathy, and 2 other patients with normal neurological signs had upper cervical fusions performed for severe occipital headache. This small group of rheumatoid patients who are at risk of developing cervical myelopathy cannot be predicted with certainty, but can be selected out at an early stage by performing regular radiographs of hands, feet, and cervical spine.

Chronic treatment with 1-aminocyclopropanecarboxylic acid desensitizes behavioral responses to compounds acting at the N-methyl-D-aspartate receptor complex

Functional antagonists at the N-methyl-D-aspartate (NMDA) receptor complex produce anti-depressant-like actions in preclinical models. Thus, an injection of a glycine partial agonist (1-aminocyclopropanecarboxylic acid; ACPC), a competitive NMDA antagonist (2-amino-7-phosphonoheptanoic acid; AP-7) or a use-dependent cation channel blocker (MK-801) reduced immobility in the forced swim test (FST) with efficacies comparable to imipramine (Trullas and Skolnick 1990). Seven daily injections of ACPC (200-400 mg/kg) abolished the effects of both this compound (200-1200 mg/kg) and AP-7 (200-300 mg/kg) in the FST. The loss in effectiveness of ACPC required 7 days of treatment to become fully manifest, and was reversed by discontinuing treatment. Other agents active in the FST (e.g. MK-801, imipramine, and nifedipine) were unaffected by this regimen. Moreover, ACPC and AP-7 remained active in the FST following repeated injections of MK-801, AP-7, or imipramine. Chronic treatment with ACPC did not affect its actions in the elevated plus-maze, but significantly attenuated the convulsant and lethal effects of NMDA (125 mg/kg). Tissue levels of ACPC indicate the modified behavioral responses produced by chronic treatment are not attributable to pharmacokinetic factors. These findings suggest repeated administration of ACPC may effect an "uncoupling" of NMDA and glycine receptors, resulting in an apparent desensitization of the behavioral actions of substances acting at these sites.

Structure and biology of amylin

Amylin is a recently discovered 37 amino acid peptide secreted into the bloodstream, along with insulin, from pancreatic beta-cells. It is about 50% identical to calcitonin gene-related peptides (CGRP alpha and CGRP beta) and structurally related to the calcitonins. Amylin can elicit the vasodilator effects of CGRP and the hypocalcaemic actions of calcitonin, while these peptides can mimic newly discovered actions of amylin on carbohydrate metabolism. The different relative potencies of these peptides suggest that they act with different selectivities at a family of receptors. Amylin is deficient in insulin-dependent diabetes mellitus, while plasma levels are elevated in insulin-resistant conditions such as obesity and impaired glucose tolerance. In this Viewpoint article, Tim Rink and colleagues propose that amylin is an endocrine partner to insulin and glucagon; deficiency or excess of amylin may therefore contribute to important metabolic diseases.

Treadmill walking in old age may not reproduce the real life situation

OBJECTIVE

In a preliminary study in our laboratory, healthy elderly people had a higher heart rate during treadmill walking than during corridor walking at the same speed. The objective of this study was to determine whether this initial observation, (1) persisted after repeated testing, (2) was present in younger adults, (3) was due to wearing a mouthpiece during treadmill walking, or (4) was due to a change in gait.

DESIGN

A study of elderly and young volunteers undergoing repeated testing, with comparison of treadmill walking with corridor walking.

SETTING

The Royal Free Hospital School of Medicine.

PARTICIPANTS

Twelve healthy elderly (71-80 years) and 12 healthy young (21-37 years) volunteers.

MAIN OUTCOME MEASURES

Heart rate (beats/min) and step rate (steps/min) during comfortable self-paced corridor walking and during treadmill walking at the same speed.

MAIN RESULTS

The elderly subjects had higher heart rates during treadmill walking than during corridor walking at the same speed (mean difference = 6 beats/min, 95% Confidence Interval (CI) = 1 to 10). This difference increased (to a mean of 11 beats/min, 95% CI = 5 to 16) when a mouthpiece was worn on the treadmill. These differences persisted after repeated testing. The young subjects did not have higher heart rates on the treadmill, (with or without the mouthpiece). In both groups, step rate was lower (95% CI = -9 to -2, elderly; -5 to -2, young) during treadmill walking, corresponding to a 3% increase in stride length.

CONCLUSION

The heart rate response to treadmill walking in healthy elderly people may be less representative of the "real life" situation than in younger adults.

Agalactosyl IgG: an aid to differential diagnosis in early synovitis

Sixty consecutive patients presenting with early-onset synovitis were studied by measuring rheumatoid factor (RF) titers and the percentage of oligosaccharide chains attached to the C gamma 2 domain of IgG that lack galactose (GAL[0]). After 2 years of followup, 39 patients (65%) had developed rheumatoid arthritis (RA), and 21 had developed a variety of other inflammatory joint diseases. A combination of RF positivity and GAL(0) levels above the age-corrected mean gave a positive predictive value for a diagnosis of RA in 94% of these patients. These observations may well have clinical utility.

Contemporary patterns of care and disease activity outcome in early rheumatoid arthritis: the ERAN cohort

OBJECTIVES

To report from the Early Rheumatoid Arthritis Network (ERAN), time from symptom onset to start of therapy, treatment choices and disease outcome in early RA.

METHODS

Patients with newly diagnosed RA were prospectively enrolled from 19 centres in the UK and Eire. Standardized information was collected on case report forms at first presentation, 3-6 months, 1 yr and annually thereafter. The choice and intensity of drug treatment was left to the discretion of individual centres.

RESULTS

A total of 808 patients were recruited between 2002 and 2007, with a mean follow-up of 16 (0-60) months. Of them, 62% fulfilled four or more ACR criteria for RA at first visit. The median time from onset of symptoms to referral to secondary care was 4 months [interquartile range (IQR) 2-9, n = 655] and to start of first DMARD 8 months (IQR 4-13, n = 638). DMARDs were prescribed in 97% of the patients, initially as monotherapy in 91%, and as combination therapy in 9%. The second DMARD (n = 220) was a switch to another as monotherapy in 52% and step-up to combination therapy in 48%. The proportions with a 28-joint disease activity score >5.1 at baseline and 3 yrs were 46 and 19%, >3.2 were 84 and 54% and <2.6 were 6 and 33%, respectively.

CONCLUSIONS

Patients presenting with RA in ERAN do not receive DMARDs promptly, largely due to delays in referral to secondary care. Contemporary treatment practice is to start with DMARD monotherapy, and to use combination DMARDs as second-line therapy in approximately half of them. Over 3 yrs the proportion of patients continuing to have active disease remains high.

Variations in the pattern of muscle innervation by the L5 and S1 nerve roots

Evidence based on electrical studies is presented for the standard and anomalous patterns of innervation of muscles supplied by the fifth lumbar and first sacral nerve roots. Although considerable controversy still exists, previous work in this field suggests that the L5 nerve root supplies tibialis anterior, extensor hallucis longus, extensor digitorum brevis, and the lateral head of gastrocnemius, while the S1 nerve root innervates the medial head of gastrocnemius, soleus, and abductor hallucis. In order to confirm the reliability of this data, the L5 and S1 nerve roots of 50 patients were electrically stimulated during surgery, and distally evoked responses in the relevant muscles were recorded, using surface electrodes. The results confirm the essential reliability of the proposed table of segmental innervation and also demonstrate that most muscles have a dual innervation, with one nerve root being dominant. However, eight patients (16%) exhibited a marked departure from the normal pattern. For example, it is clear that on occasion the extensor digitorum brevis and the lateral head of gastrocnemius can be supplied by S1 and the soleus and medial head of gastrocnemius can be supplied by L5. In a prospective study of 100 patients presenting with clinical evidence of lumbosacral nerve root entrapment, the level of nerve root involvement, as predicted by electromyography, was compared with the operative findings. Correct preoperative nerve root localization was achieved in 84%.(ABSTRACT TRUNCATED AT 250 WORDS)

Changes in the expression of nitric oxide synthase in the human uterine cervix during pregnancy and parturition

Nitric oxide (NO) has been proposed as a mediator of cervical ripening. We investigated the expression, using Western blotting, and localization, using immunohistochemistry, of the nitric oxide synthase (NOS) enzymes, inducible NOS (iNOS), endothelial NOS (eNOS) and neuronal NOS (bNOS) in the human cervix during pregnancy and parturition. Cervical biopsies were obtained from non-pregnant women, women in the first trimester of pregnancy, and pregnant women at term before and after the onset of labour. Each of the NOS isoforms was localized in the cervices of both non-pregnant and pregnant subjects using immunohistochemistry. iNOS expression was significantly greater in early pregnancy compared with the non-pregnant state (P: < 0.005). iNOS expression was up-regulated further in samples obtained in the third trimester compared with the first trimester. bNOS expression was greater in samples from the first trimester of pregnancy than in non-pregnant samples (P: < 0. 005), but showed no additional increase in late pregnancy or with the onset of labour. eNOS expression was increased in samples obtained in the third trimester both before (P: = 0.002) and after the onset of labour (P: < 0.002) when compared with non-pregnant samples. The increased expression of NOS isoforms in late pregnancy supports the hypothesis that NO is involved in the process of cervical ripening.

Reflex inhibition of the quadriceps after meniscectomy: lack of association with pain

We have examined the severity and duration of reflex inhibition of quadriceps activation after arthrotomy and meniscectomy, its relationship with pain, and the effect of local anaesthesia on this relationship. Fourteen men, on completion of medial meniscectomy by arthrotomy, received either 10 ml (B10 group) or 15 ml (B15 group) of 0.5% bupivacaine hydrochloride ('Marcaine Plain') into the knee, or no injection (control group). Reflex inhibition of quadriceps was measured as the percentage reduction, from the ipsilateral preoperative value, in the integrated surface electromyogram recorded during maximal voluntary isometric contractions with the knee in extension. Pain during each contraction was recorded on a linear analogue scale. Unoperated limbs showed no evidence of quadriceps inhibition. In the operated limbs, at 1-2 h post-operatively, controls had both severe inhibition (median = 62%) and severe pain on attempting a maximal quadriceps contraction. The B10 group had similar inhibition but less pain (P less than or equal to 0.005, Wilcoxon 2-sample, 1-tailed test). In the B15 group both inhibition (P less than or equal to 0.05) and pain (P less than or equal to 0.01) were less than in the controls. These effects of bupivacaine had been lost by 4-5 h post-operatively. At 3-4 days, inhibition was still severe (median = 75%) in all three groups of patients but pain was only mild or absent. At 10-15 days, median inhibition was still 35%, but there was little or no pain. We conclude that postmeniscectomy inhibition is not simply due to perceived pain but is due, at least in part, to stimuli from the knee.

Replication of genetic loci for ages at menarche and menopause in the multi-ethnic Population Architecture using Genomics and Epidemiology (PAGE) study

STUDY QUESTION

Do genetic associations identified in genome-wide association studies (GWAS) of age at menarche (AM) and age at natural menopause (ANM) replicate in women of diverse race/ancestry from the Population Architecture using Genomics and Epidemiology (PAGE) Study?

SUMMARY ANSWER

We replicated GWAS reproductive trait single nucleotide polymorphisms (SNPs) in our European descent population and found that many SNPs were also associated with AM and ANM in populations of diverse ancestry.

WHAT IS KNOWN ALREADY

Menarche and menopause mark the reproductive lifespan in women and are important risk factors for chronic diseases including obesity, cardiovascular disease and cancer. Both events are believed to be influenced by environmental and genetic factors, and vary in populations differing by genetic ancestry and geography. Most genetic variants associated with these traits have been identified in GWAS of European-descent populations.

STUDY DESIGN, SIZE, DURATION

A total of 42 251 women of diverse ancestry from PAGE were included in cross-sectional analyses of AM and ANM.

MATERIALS, SETTING, METHODS

SNPs previously associated with ANM (n = 5 SNPs) and AM (n = 3 SNPs) in GWAS were genotyped in American Indians, African Americans, Asians, European Americans, Hispanics and Native Hawaiians. To test SNP associations with ANM or AM, we used linear regression models stratified by race/ethnicity and PAGE sub-study. Results were then combined in race-specific fixed effect meta-analyses for each outcome. For replication and generalization analyses, significance was defined at P < 0.01 for ANM analyses and P < 0.017 for AM analyses.

MAIN RESULTS AND THE ROLE OF CHANCE

We replicated findings for AM SNPs in the LIN28B locus and an intergenic region on 9q31 in European Americans. The LIN28B SNPs (rs314277 and rs314280) were also significantly associated with AM in Asians, but not in other race/ethnicity groups. Linkage disequilibrium (LD) patterns at this locus varied widely among the ancestral groups. With the exception of an intergenic SNP at 13q34, all ANM SNPs replicated in European Americans. Three were significantly associated with ANM in other race/ethnicity populations: rs2153157 (6p24.2/SYCP2L), rs365132 (5q35/UIMC1) and rs16991615 (20p12.3/MCM8). While rs1172822 (19q13/BRSK1) was not significant in the populations of non-European descent, effect sizes showed similar trends.

LIMITATIONS, REASONS FOR CAUTION

Lack of association for the GWAS SNPs in the non-European American groups may be due to differences in locus LD patterns between these groups and the European-descent populations included in the GWAS discovery studies; and in some cases, lower power may also contribute to non-significant findings.

WIDER IMPLICATIONS OF THE FINDINGS

The discovery of genetic variants associated with the reproductive traits provides an important opportunity to elucidate the biological mechanisms involved with normal variation and disorders of menarche and menopause. In this study we replicated most, but not all reported SNPs in European descent populations and examined the epidemiologic architecture of these early reported variants, describing their generalizability and effect size across differing ancestral populations. Such data will be increasingly important for prioritizing GWAS SNPs for follow-up in fine-mapping and resequencing studies, as well as in translational research.