sex-linked

adj. describing either a gene that is located on one of the sex chromosomes, typically the X chromosome (X-linked), or a trait determined by such a gene. The process whereby a sex-linked gene or trait is passed on from parent to offspring is called sex-linked inheritance. Sex-linked inherited diseases from a defective gene on the X chromosome include hemophilia, itself called X-linked recessive because the defective gene is usually a recessive allele. It is carried by females and expressed mostly in their male offspring. In their daughters, who have two X chromosomes, the defective gene is usually masked by the normal, dominant allele on the other X chromosome, whereas in their sons, who have an X and a Y chromosome and in whom the Y chromosome lacks many of the alleles of the X chromosome, masking cannot occur. Disorders that are X-linked dominant, in which only one copy of an allele of a defective gene on the X chromosome is sufficient to cause inherited disorder, may occur in either male or female offspring depending on which parent is affected. A form of sex-linked inheritance in which a recessive trait is inherited from father to son by way of a single gene on the Y chromosome (Y-linked) affects only male offspring. Diseases or disorders passed on through Y-linked inheritance are rare.

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Psychology term of the day

March 11th 2025

burnout

n. physical, emotional, or mental exhaustion accompanied by decreased motivation, lowered performance, and negative attitudes toward oneself and others. It results from performing at a high level until stress and tension, especially from extreme and prolonged physical or mental exertion or an overburdening workload, take their toll. The word was first used in this sense in 1975 by U.S. psychologist Herbert J. Freudenberger (1926–1999) in referring to workers in clinics with heavy caseloads. Burnout is most often observed in professionals who work in service-oriented vocations (e.g., social workers, teachers, correctional officers) and experience chronic high levels of stress. It can be particularly acute in therapists or counselors doing trauma work, who feel overwhelmed by the cumulative secondary trauma of witnessing the effects. Burnout is also experienced by athletes when continually exposed to stress associated with performance without commensurate rewards or rest. See also overtraining syndrome; vital exhaustion.