These filaments, in turn, elongate the red blood cells found in sickle-cell disease.

For over 50 years, this has been the only known textbook example in which a mutation causes such filaments to form.

According to Dr. Emmanuel Levy and his group in the Weizmann Institute of Science's Structural Biology Department, Lego-like assemblies should have formed relatively frequently during evolution.

And since identical units are produced from the same gene, each genetic mutation is repeated multiple times in the complex.

Unlike amyloid-like protein fibers, the complexes in these stacks do not change shape or unfold in order to assemble.

The stickiness occurs because the mutation substitutes an amino acid that is normally hydrophilic -- "water-loving" -- with one that is hydrophobic -- "water-hating."

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