Founder effect
Founder effect: The positive effect on gene frequency when a population (colony) has only a small number of original settlers, one or more of whom had that gene. For example, the gene for Huntington’s disease was introduced into the Lake Maracaibo region in Venezuela early in the nineteenth century. This is now the largest known aggregation of the Huntington’s gene in the world.
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- G6PD deficiency
Deficiency of the enzyme glucose-6-phosphate dehydrogenase (G6PD), the most common enzyme defect of medical importance. About 10 percent of American black males have G6PD deficiency, as do a lesser percent of black females. G6PD deficiency is also increased in frequency in people of Mediterranean origin (including Italians, Greeks, Arabs, and Jews). The gene encoding G6PD […]
- Gage, Phineas
Gage, Phineas: The most famous patient to have survived severe damage to the brain and the first from whom something was learned about the relation between personality and the function of the front parts (the frontal lobes) of the brain. During work on a railroad in 1848, an unplanned explosion propelled a rod through Gage’s […]
- Gain-of-function mutation
Gain-of-function mutation: A mutation that confers new or enhanced activity on a protein. Loss-of-function mutations, which are more common, result in reduced or abolished protein function.
- Gait
Gait: A manner of walking. Observation of gait can provide early diagnostic clues for a number of disorders, including cerebral palsy, Parkinson’s disease, and Rett syndrome.
- Galactorrhea
Galactorrhea: The spontaneous flow of milk from the nipple at any time other than during nursing. Galactorrhea can be due to “normal” factors such as an unrecognized pregnancy, trauma, surgery, overexercise or one of a number of drugs (including amphetamine, cimetidine, female hormone replacement therapy, hydroxyzine, methyldopa, nicotine, narcotics, reserpine, antidepressants of the so-called tricyclic […]