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The Scientific Basis of Medicine
Published in John S. Axford, Chris A. O'Callaghan, Medicine for Finals and Beyond, 2023
Chris O'Callaghan, Rachel Allen
Monogenic diseases are the simplest genetic disorders to study as they tend to follow Mendelian genetics. Dominant and recessive diseases have characteristic patterns of inheritance (Figure 2.10). Dominant traits require only one defective copy to generate a disease phenotype. In contrast, recessive disorders are only visible when both copies of a gene are mutated. Recessive disorders often result from a loss in biological activity for the relevant protein. Sex linkage alters Mendelian genetics, as males carry only one copy of the X chromosome; recessive mutations carried on this chromosome behave as if dominant in men, while heterozygous females act as asymptomatic ‘carriers’. Polygenic disorders have a known genetic component (such as type 1 diabetes) but involve many genes and often environmental factors too (Table 2.1). In such cases, disease results from a combination of multiple polymorphisms, acting in concert with external factors. The risk of disease conveyed by each individual genetic variant in a polygenic disorder is relatively low and much lower than that conveyed by a genetic mutation in a monogenic disorder.
Autoreactive B Cells in Collagen-Induced Arthritis
Published in Thomas F. Kresina, Monoclonal Antibodies, Cytokines, and Arthritis, 2020
Susceptibility to RA is to a large extent genetically determined. First, females are more often affected than males, a sex linkage that cannot easily be explained by the actions of sex hormones since estrogens have been found to protect against disease (92). It is possible that sex chromosomes may be of importance to the observed sex linkage. Second, the susceptibility to RA is linked to MHC class II genes coding for HLA-DR4 and HLA-DR1, and this linkage is even closer when specific determinants on the class II molecules are defined. Thus, a strong correlation has been found with HLA-Dw4 and Dw14 subtypes of DR4 that have sequence similarities at position 70–71 on the DRB chain (93). The observed MHC class II linkage is a strong indication that RA is a T cell-mediated immunospecific disease.
The Jackson Laboratory Mouse Mutant Resource
Published in John P. Sundberg, Handbook of Mouse Mutations with Skin and Hair Abnormalities, 2020
Genetic analysis — The most important feature of mutations is that they are genetically transmitted and can be propagated. No matter how valuable a new deviant may appear, it is useless unless it is reproducible and can be maintained and made available to other scientists. Each new deviant is crossed to an unrelated strain to determine whether the characteristic is transmitted to offspring and, if it is, the mode of inheritance. If the characteristic appears among the F1 progeny, it is inherited as a dominant or X-linked mutation, if the abnormal phenotype does not appear among the F1 progeny, they are intercrossed, since a recessive character will reappear in about one fourth of the F2 progeny. A semi-dominant gene will produce an intermediate phenotype in F1 progeny, and both the intermediate and original phenotypes will be recovered in the F2 generation. X-linkage will be detected by sex-related transmission patterns. Each new mutation is tested for allelism to any previously identified gene that produces a similar phenotype. This is done by direct crosses between mice carrying the two mutations. With the increased efficiency of our linkage testing strategies, however, it is sometimes easier to establish chromosomal location of a new gene first and then test for allelism with genes on the chromosome if any produce a similar phenotype.
The Interplay of Sexual Arousal and Power-Related Emotions in Men’s Alcohol-Involved Sexual Aggression Intentions
Published in The Journal of Sex Research, 2022
Kelly Cue Davis, Elizabeth C. Neilson, Mitchell Kirwan, Elizabeth R. Bird, Nolan Eldridge, William H. George, Cynthia A. Stappenbeck
Although extant research has demonstrated that power-related sex motives play a contributing role in men’s sexually aggressive behavior, findings to date have relied upon assessments of more distal predictors of the power-sex linkage such as beliefs, attitudes, and implicit associations. Missing from these examinations are more proximal, emotion-related assessments of the role of power in sexual aggression. Interviews with perpetrators suggest that in-the-moment feelings of power and dominance are key rewarding features of sexual aggression. For example, in their seminal 1985 study involving interviews with convicted rapists, Scully and Marolla (1985) reported that one perpetrator noted “Rape gave me the power to do what I wanted … I felt in control, dominant,” while another stated “With rape, I felt totally in charge” (p. 259). Although it is logical that tendencies to engage in sex for power-related reasons would be predictive of experiencing greater feelings of power during sexual aggression, this supposition has not been tested empirically. The present study sought to address this gap in the literature by investigating the connection between power-related sexual motives and the proximal experience of power and dominance feelings during a hypothetical sexual aggression situation.
Deconstructing autism: from unitary syndrome to contributory developmental endophenotypes
Published in International Review of Psychiatry, 2018
The above considerations consequently bring us back to a more sophisticated understanding of how molecular genetic variants might relate to the development of ASD and other complex neuropsychiatric syndromes. It is now known that autism is associated with a diversity of rare and common genetic variants involving hundreds (Sanders et al., 2015), if not thousands (Boyle, Li, & Pritchard, 2017) of different genes. It is important to note that most of the molecular genetic variants that have been statistically associated with autism are autosomal (i.e. not on sex chromosomes), indicating that the universally-observed sex ratio in autism arises from mechanisms other than sex linkage. The inference from a vast amount of family recurrence and molecular genetic data that has accumulated to date is that most—but not all—females are relatively ‘protected’ from most—but not all—inherited forms of autism (Constantino, 2016; Constantino et al., 2010; Jacquemont et al., 2014; Palmer et al., 2017). This suggests at least one highly parsimonious resiliency factor that operates against numerous genetic liabilities to ASD.
Evaluation of the healthcare resource use and the related financial costs of managing peanut allergy in the United Kingdom
Published in Expert Review of Clinical Immunology, 2019
Laura A. Scott, Thomas R. Berni, Ellen R. Berni, Jane De Vries, Craig J. Currie
Matched controls were selected from patients with no history of food allergies to compare health-care costs between peanut-allergic population and the general population. The first group (simple-matched) was matched 1:1 on their year of birth, general practice, sex, linkage status to corresponding datasets and registration year. The second group (atopy-matched) was matched on the same characteristics plus atopic status; that is, whether a patient had a diagnosis of asthma, eczema and/or allergic rhinitis identified by Read codes in CPRD and ICD-10 codes in HES inpatient data.