BRCA 1 and 2--A Genetic Link to Familial Breast and Ovarian Cancer

, , , Duke University Medical Center

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Linkage Analysis:
Linkage analysis uses certain known sequences of non-coding DNA as a marker for disease-causing loci within the genome. These sequences consist of short repeats of DNA base-pair sequences. The number of repeats at each known site varies throughout the population and, therefore, the sequences may be used as markers for the inheritance of nearby, or linked, disease genes.

Positional Cloning:
Method of isolating a disease-causing gene in which coding sequences within previously identified small regions of DNA, together with any known (candidate) genes, are screened for mutations in affected individuals. This technique is generally used in the absence of biological information on the functional defect causing a disease, thus providing a foothold for other methods of gene identification.

RING/Zinc Finger:
A highly conserved DNA sequence that encodes a protein capable of specific interactions with DNA. Derives its name from the 3-dimensional interaction of 2 pairs of cysteines and histidines with zinc atoms, in a manner similar to fingers of a hand. Many regulatory proteins have been described containing such zinc finger domains.

Ankyrin Repeats:
Ankyrins are proteins involved in binding of spectrin to cell-membrane proteins. Ankyrin repeats were first described as homologous sequences in cell-cycle proteins, and have since been detected in several regulatory proteins. The repeat has a length of approximately 33 amino acids and is present in phylogenically diverse proteins including animal, yeast, plant, and prokaryotes.[1]


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