A gene for muscle wasting causes heart disease in women
Damage to the so-called dystrophin gene not only causes a dangerous form of muscle atrophy, but can also cause heart disease. Researchers at the International Center for Genetic and Biotechnology in Trieste, Italy, have found this out. It is always boys who suffer from Duchenne muscular dystrophy. Although they are born symptom-free, their muscles atrophy in the first few years. The young usually die before they reach the age of 20.
Muscle wasting is caused by a defective gene. When intact, it produces a protein called dystrophin, which plays a central role in muscle cells. If the gene is defective, the dystrophin is also not produced correctly.
The scientist Luisa Mestroni from the Trieste Gene Center now reports that mutations in the dystrophin gene can also cause heart disease: Depending on which area in the dystrophin gene is changed, different clinical pictures develop. Usually only men affected by diseases caused by the dystrophin gene because it is on an X chromosome. Women have two of them, they can compensate for the defect with their second X chromosome. However, like all men, their sons have a male Y chromosome instead of the second X-, which would cause the inherited muscle disease to break out. Mestroni: Our patients suffered from heart disease, but they had no signs of muscle wasting. However, the mutations in the dystrophin gene were detectable. This means that these mutations only led to heart disease in them and did not cause the typical muscle atrophy.
Although women can in principle compensate for the genetic defect, they can only do this with certainty in the muscle cells. Because here each fiber has several cell nuclei. In some, the unfavorable chromosome works, in others the intact one, so that the disease can be prevented. The situation in the heart is different. There are individual cells that are only controlled by a cell nucleus. Chance decides whether the intact genetic material is working in the cell. This also causes severe heart disease in women, although doctors have so far ruled out this genetic cause.
