| frameshift mutation | <molecular biology> A type of mutation that results from insertion or deletion of a single nucleotide into, or from, an open reading frame in the normal DNA sequence. Normally, the genetic code is read in the wrong frame, three nucleotides at a time, and the entire sequence downstream of the mutation, is translated into a polypeptide with a garbled amino acid sequence from the mutated codon onwards. These mutations may be induced by certain types of mutagens or may occur spontaneously and usually result in the generation, downstream, of nonsense, chain termination codons. Synonym: addition mutation, addition-deletion mutation, deletion mutation, reading-frameshift mutation. (21 Jun 2000) |
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| lethal mutation | <genetics, molecular biology> Mutation that eventually results in the death of an organism carrying the mutation. (18 Nov 1997) |
| Aaron's sign | <clinical sign> In acute appendicitis, a referred pain or feeling of distress in the epigastrium or precordial region on continuous firm pressure over McBurney's point. (05 Mar 2000) |
| Abadie's sign of tabes dorsalis | Insensibility to pressure over the tendo achillis. (05 Mar 2000) |
| Abrahams' sign | <clinical sign> An obsolete sign: Rales and other adventitious sounds, changes in the respiratory murmurs, and increase in the whispered sound can be heard on auscultation over the acromial end of the clavicle some time before they become audible at the apex; heard primarily in pulmonary tuberculosis affecting the apical portion of the lung, a dull-flat note, i.e., one between the normal dullness at the right apex and absolute flatness, heard on percussion in that region, indicating progress from incipient to advanced tuberculosis. (05 Mar 2000) |
| accessory sign | <clinical sign> A finding frequently but not consistently present in a disease. Synonym: assident sign. (05 Mar 2000) |
| Allis' sign | <clinical sign> In fracture of the neck of the femur, the trochanter rides up, relaxing the fascia lata, so that the finger can be sunk deeply between the great trochanter and the iliac crest. (05 Mar 2000) |
| Amoss' sign | <clinical sign> In painful flexion of the spine, it is necessary to support a sitting position by extending the arms behind the torso with the weight placed on the hands. (05 Mar 2000) |
| Anghelescu's sign | <clinical sign> In vertebral tuberculosis, painful or impossible flexion of the spine when the patient attempts to rest weight on the heels and occiput. (05 Mar 2000) |
| antecedent sign | <clinical sign> A sign that appears during the prodrome of a disease. Synonym: antecedent sign. (05 Mar 2000) |
| assident sign | <clinical sign> A finding frequently but not consistently present in a disease. Synonym: assident sign. (05 Mar 2000) |
| Auenbrugger's sign | <clinical sign> An epigastric prominence seen in cases of marked pericardial effusion. (05 Mar 2000) |
| Aufrecht's sign | <clinical sign> An obsolete sign: diminished breath sounds in the trachea just above the jugular notch, in cases of stenosis. (05 Mar 2000) |
| B6 bronchus sign | In lung radiology, appearance of an air bronchogram of the superior segmental bronchus of the lower lobe because of segmental atelectasis or consolidation. (05 Mar 2000) |
| Babinski's sign | <clinical sign> Extension of the great toe and abduction of the other toes instead of the normal flexion reflex to plantar stimulation, considered indicative of pyramidal tract involvement ("positive" Babinski). Synonym: Babinski reflex, Babinski's phenomenon, great-toe reflex, paradoxical extensor reflex, toe phenomenon. (05 Mar 2000) |