| X-linked gene | A gene located on an X chromosome. (05 Mar 2000) |
|---|---|
| X-linked hypogammaglobulinaemia | A congenital, X-linked recessive, primary immunodeficiency characterised by decreased numbers (or absence) of circulating B-lymphocytes with corresponding decrease in immunoglobulins of the five classes; associated with marked susceptibility to infection by pyogenic bacteria (notably, pneumococci and Haemophilus influenzae) beginning after loss of maternal antibodies. X-linked hypogammaglobulinaemia with growth hormone deficiency, hypogammaglobulinaemia combined with a reduced number of B-cells; characterised by short stature, delayed puberty, and recurrent infections. (05 Mar 2000) |
| X-linked ichthyosis | A form of ichthyosis, due to 3-beta-hydroxysteroidsulfate sulfatase deficiency, that appears at birth or in early infancy and affects males; characterised by scaling predominantly on the neck and trunk but not on the palms and soles; histologically, there is hyperkeratosis, a granular layer in the epidermis, and normal epidermal cell turnover. Synonym: steroid sulfatase deficiency. (05 Mar 2000) |
| X-linked inheritance | The pattern of inheritance that may result from a mutant gene on an X chromosome. (05 Mar 2000) |
| X-linked locus | Any locus that in normal karyotypes is borne on the X chromosome. (05 Mar 2000) |
| sex-linked | <genetics> A genetic disorder where the genetic defect is linked to one of the chromosomes that determines sex (x or y). This is usually due to a gene on the unpaired portion of the X chromosome. Recessive X linked alleles are fully expressed in the heterogametic sex because they can have only one copy of the gene. Thus X linked mutant disorders are more common in human males than in females. An example is haemophilia, which is autosomal recessive and linked to the X chromosome, so only males (XY) actually manifest the disease. (06 Oct 1997) |
| sex-linked character | An inherited character determined by a gene on a gonosome. See: gene. (05 Mar 2000) |
| sex-linked inheritance | The pattern of inheritance that may result from a mutant gene located on either the X or Y chromosome. (05 Mar 2000) |
| sex-linked locus | Any locus that in normal karyotypes is borne on a heterosome; commonly but incorrectly applied to an X-linked locus. (05 Mar 2000) |
| N-acetylated-alpha-linked acidic dipeptidase | <enzyme> Chloride-dependent membrane bound metallopeptidase, most active with the endogenous neuropeptide n-acetyl-l-aspartyl-l-glutamate Registry number: EC 3.4.13.- Synonym: naaladase, glutamate carboxypeptidase II, prostate-specific membrane antigen, psm antigen (26 Jun 1999) |
| ichthyosis, x-linked | Chronic form of ichthyosis that is inherited as a sex-linked recessive trait carried on the x-chromosome and transmitted to the male offspring. It is characterised by severe scaling, especially on the extremities, and is associated with steroid sulfatase deficiency. (12 Dec 1998) |
| enzyme-linked immunoabsorbent assay | <investigation> The enzyme-linked immunoabsorbent assay is serologic test used as a general screening tool for the detection of antibodies to the HIV virus. Reported as positive or negative. Since false positive tests due occur (for example recent flu shot), positives will require further evaluation using the western blot. ELISA technology links an a measurable enzyme to either an antigen or antibody. In this way, it can then measure the presence of an antibody or an antigen in the bloodstream. Acronym: ELISA (27 Sep 1997) |
| enzyme-linked immunosorbent assay | An immunoassay utilizing an antibody labelled with an enzyme marker such as horseradish peroxidase. While either the enzyme or the antibody is bound to an immunosorbent substrate, they both retain their biologic activity; the change in enzyme activity as a result of the enzyme-antibody-antigen reaction is proportional to the concentration of the antigen and can be measured spectrophotometrically or with the naked eye. Many variations of the method have been developed. (12 Dec 1998) |
| expression-linked copy | <molecular biology> One of many different versions of the variable surface glycoprotein gene of the trypanosome (a parasitic protozoan which causes the disease African sleeping sickness), refers to whichever one of them is currently being expressed on the outer surface of the trypanosome. (09 Oct 1997) |
| y-linked | A gene on the Y chromosome. A y-linked gene is by necessity passed from father to son. (12 Dec 1998) |