But in 1991 British researchers identified a gene defect that causes rare, early-onset Alzheimer's.

FORBES: Executive Health

The scientists will now begin work to look at exactly how the gene defect affects fibroid growth.

BBC: Gene defects have been linked to fibroids

Despite some similar symptoms such as lack of motor control, SMA is caused by an unrelated gene defect.

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They also are often terrified of what will happen if they decide to have another child, and the test can tell them whether they are carrying a gene that caused the defect.

FORBES: DNA Sequencing: Is Science Fiction Becoming Medical Fact?

The scientists used tests on mice to determine whether a defect in this gene is enough to trigger DCM.

BBC: Gene link to inherited heart disease

They found that a mouse with a defect on the phospholamban gene also suffered severe damage to its heart.

BBC: Gene link to inherited heart disease

Duchenne muscular dystrophy, discovered by French neurologist Guillaume Duchenne in 1868, accounts for 40% of the cases of muscular dystrophy in the U.S. In 1987 it became one of the first ailments linked to a defect in a particular gene, but since then the main treatments have been limited and unable to halt the disease's devastating effects.

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