Effect of mass selection on the within-family genetic variance in finite populations

Summary The adequacy of an expression for the withinfamily genetic variance under pure random drift in an additive infinitesimal model was tested via simulation in populations undergoing mass selection. Two hundred or one thousand unlinked loci with two alleles at initial frequencies of 1/2 were considered. The size of the population was 100 (50 males and 50 females). Full-sib matings were carried out for 15 generations with only one male and one female chosen as parents each generation, either randomly or on an individual phenotypic value. In the unselected population, results obtained from 200 replicates were in agreement with predictions. With mass selection, within-family genetic variance was overpredicted by theory from the 12th and 4th generations for the 1,000 and 200 loci cases, respectively. Taking into account the observed change in gene frequencies in the algorithm led to a much better agreement with observed values. Results for the distribution of gene frequencies and the withinlocus genetic covariance are presented. It is concluded that the expression for the within-family genetic variance derived for pure random drift holds well for mass selection within the limits of an additive infinitesimal model.     

Multicentre study of cancer pain and its treatment in France.

OBJECTIVE--To describe the treatment of cancer pain in France and to evaluate the predictive factors for inadequate management. DESIGN--Multicentre, representative cross sectional survey. SETTING--20 treatment centres, including cancer centres, university hospitals, state hospitals, private clinics, and one homecare setting (in which patients are supported at home). SUBJECTS--605 patients with cancer. MAIN MEASURES--Patients rated prevalence and severity of pain and functional impairment related to pain. Doctors reported patients'' cancer characteristic, performance status, pain severity, and analgesic drugs ordered. RESULTS--57% (340/601) of patients with cancer reported pain due to their disease, and, of those with pain, 69% (224/325) rated their worst pain at a level that impaired their ability to function. 30% (84/279) were reported as receiving no drugs for their pain. Of the 270 patients in pain for whom information on treatment was available 51% (137/270) were not receiving adequate pain relief, according to an index based on the World Health Organisation''s guidelines. French doctors were found to underestimate the severity of their patients'' pain. Younger patients, patients without metastatic disease, patients with a better performance status, and patients who rated their pain as more severe than their doctors did were at greater risk for undertreatment of their pain. CONCLUSIONS--In the light of the high prevalence and the severity of pain among patients with cancer, the assessment and treatment of cancer pain in France remain inadequate, emphasising the need for changes in patient care.