So far in this course we have dealt entirely with the evolution of characters that are controlled by simple Mendelian inheritance at a single locus. There are notes on the course website about gametic disequilibrium and how allele frequencies change at two loci simultaneously, but we didn’t discuss them. In every example we’ve considered we’ve imagined that we could understand something about evolution by examining the evolution of a single gene. That’s the domain of classical population genetics. For the next few weeks we’re going to be exploring a field that’s actually older than classical population genetics, although the approach we’ll be taking to it involves the use of population genetic machinery. If you know a little about the history of evolutionary biology, you may know that after the rediscovery of Mendel’s work in 1900 there was a heated debate between the “biometricians” (e.g., Galton and Pearson) and the “Mendelians” (e.g., de Vries, Correns, Bateson, and Morgan). Biometricians asserted that the really important variation in evolution didn’t follow Mendelian rules. Height, weight, skin color, and similar traits seemed to

Human biochemical genetics

Sex, Gender, and Pain: A Review of Recent Clinical and Experimental Findings

https://research.vu.nl/ws/files/118982316/Hartvigsen2018_What_low_back_pain_is_and_why_we_need_to_pay_attention.pdf

What low back pain is and why we need to pay attention

Assessing risk of bias in prevalence studies: modification of an existing tool and evidence of interrater agreement

Prevalence of obstructive sleep apnea in the general population: A systematic review.

The objective of this study was to determine the prevalence of neck pain (NP) in the world population and to identify areas of methodological variation between studies. A systematic search was conducted in five databases (MEDLINE, EMBASE, CINAHL, OSH-ROM, and PsycINFO), followed by a screening of reference lists of relevant papers. Included papers were extracted for information and each paper was given a quality score. Mean prevalence estimates were calculated for six prevalence periods (point, week, month, 6 months, year, and lifetime), and considered separately for age, gender, quality score, response rate, sample size, anatomical definition, geography, and publication year. Fifty-six papers were included. The six most commonly reported types of prevalence were point, week, month, 6 months, year, and lifetime. Except for lifetime prevalence, women reported more NP than men. For 1-year prevalence, Scandinavian countries reported more NP than the rest of Europe and Asia. Prevalence estimates were not affected by age, quality score, sample size, response rate, and different anatomical definitions of NP. NP is a common symptom in the population. As expected, the prevalence increases with longer prevalence periods and generally women have more NP than men. At least for 1-year prevalence Scandinavian countries report higher mean estimates than the rest of Europe and Asia. The quality of studies varies greatly but is not correlated with the prevalence estimates. Design varies considerably and standardisation is needed in future studies.

/pdf/the-prevalence-of-neck-pain-in-the-world-population-a-2eorrm81jk.pdf

The prevalence of neck pain in the world population: a systematic critical review of the literature

Objective To examine the current evidence regarding the reliability and validity of hand-held dynamometry for assessment of muscle strength in the clinical setting. Data Sources A search was conducted of the following databases: Cochrane, MEDLINE, PubMed, PEDro, OTseeker, Index to Chiropractic Literature (ICL), and MANTIS, from inception until January 29, 2010. Study Selection The MeSH subject heading "muscle strength dynamometer" was searched, in isolation and in combination with the text word phrases "hand-held dynamometer" and "isokinetic." Four hundred fifty-four different studies met this search and were reviewed for possible inclusion. Data Extraction Two independent reviewers assessed the quality of the included manuscripts. The PEDro data collection system was used in conjunction with the Cochrane Diagnostic Test Accuracy Description. A third reviewer was used when there was disagreement between the primary reviewers. Data Synthesis Seventeen manuscripts met the inclusion criteria for this review, with a total of 19 studies (2 of the manuscripts involved 2 separate studies) that compared hand-held dynamometry with an identified reference standard (isokinetic muscle strength testing). The results demonstrated minimal differences between hand-held dynamometry and isokinetic testing. Conclusions Considering hand-held dynamometry's ease of use, portability, cost, and compact size, compared with isokinetic devices this instrument can be regarded as a reliable and valid instrument for muscle strength assessment in a clinical setting.

Hand-held dynamometry correlation with the gold standard isokinetic dynamometry: a systematic review.

The test-retest reliability of centre of pressure measures in bipedal static task conditions--a systematic review of the literature.

Over the past 20 years, the center of pressure (COP) has been commonly used as an index of postural stability in standing. While many studies investigated COP excursions in low back pain patients and healthy individuals, no comprehensive analysis of the reported differences in postural sway pattern exists. Six online databases were systematically searched followed by a manual search of the retrieved papers. The selection criteria comprised papers comparing COP measures derived from bipedal static task conditions on a force-plate of non-specific low back pain (NSLBP) sufferers to those of healthy controls. Sixteen papers met the inclusion criteria. Heterogeneity in study designs prevented pooling of the data so only a qualitative data analysis was conducted. The majority of the papers (14/16, 88%) concluded that NSLBP patients have increased COP mean velocity and overall excursion as compared to healthy individuals. This was statistically significant in the majority of studies (11/14, 79%). An increased sway in anteroposterior direction was also observed in NSLBP patients. Patients with NSLBP exhibit greater postural instability than healthy controls, signified by greater COP excursions and a higher mean velocity. While the decreased postural stability in NSLBP sufferers further appears to be associated with the presence of pain, it seems unrelated to the exact location and pain duration. No correlation between the pain intensity and the magnitude of COP excursions could be identified.

/pdf/center-of-pressure-excursion-as-a-measure-of-balance-379ag3z40p.pdf

Center of pressure excursion as a measure of balance performance in patients with non-specific low back pain compared to healthy controls: a systematic review of the literature

It is unclear to what extent spinal pain varies between genders and in relation to age. It was the purpose of this study to describe the self-reported prevalence of 1) pain ever and pain in the past year in each of the three spinal regions, 2) the duration of such pain over the past year, 3) pain radiating from these areas, and 4) pain in one, two or three areas. In addition, 5) to investigate if spinal pain reporting is affected by gender and 6) to see if it increases gradually with increasing age. A cross-sectional survey was conducted in 2002 on 34,902 twin individuals, aged 20 to 71 years, representative of the general Danish population. Identical questions on pain were asked for the lumbar, thoracic and cervical regions. Low back pain was most common, followed by neck pain with thoracic pain being least common. Pain for at least 30 days in the past year was reported by 12%, 10%, and 4%, respectively. The one-yr prevalence estimates of radiating pain were 22% (leg), 16% (arm), and 5% (chest). Pain in one area only last year was reported by 20%, followed by two (13%) and three areas (8%). Women were always more likely to report pain and they were also more likely to have had pain for longer periods. Lumbar and cervical pain peaked somewhat around the middle years but the curves were flatter for thoracic pain. Similar patterns were noted for radiating pain. Older people did not have pain in a larger number of areas but their pain lasted longer. Pain reported for and from the lumbar and cervical spines was found to be relatively common whereas pain in the thoracic spine and pain radiating into the chest was much less common. Women were, generally, more likely to report pain than men. The prevalence estimates changed surprisingly little over age and were certainly not more common in the oldest groups, although the pain was reported as more long-lasting in the older group.

/pdf/pain-in-the-lumbar-thoracic-or-cervical-regions-do-age-and-4pzf17156h.pdf

René Fejer

Papers

The prevalence of neck pain in the world population: a systematic critical review of the literature

Hand-held dynamometry correlation with the gold standard isokinetic dynamometry: a systematic review.

The test-retest reliability of centre of pressure measures in bipedal static task conditions--a systematic review of the literature.

Center of pressure excursion as a measure of balance performance in patients with non-specific low back pain compared to healthy controls: a systematic review of the literature

Pain in the lumbar, thoracic or cervical regions: do age and gender matter? A population-based study of 34,902 Danish twins 20–71 years of age