A mutation in the SMCHD1 gene, which leads to an increased production of the toxic DUX4 protein by the body and causes the development of shoulder-blade-facial muscular dystrophy, can cause congenital aplasia of the nasal bones (arnia). For the development of the disease, additional exposure to a modifying environmental factor, such as a virus, is necessary.
Scientists from the National Institute of Environmental Sciences (NIEHS), which is part of the National Institutes of Health (NIH) of the United States, have identified the cause of the development of a rare genetic disease – congenital aronia. The results of the study are published on the NIH website with a link to the journal Science Advances.
Recent studies have shown that type 2 shoulder-blade-facial muscular dystrophy is caused by a mutation in the SMCHD1 gene, which leads to excessive production of the DUX4 protein, which causes muscle cell death and, as a result, progressive muscle weakness. As it turned out, the DUX4 protein also leads to the death of progenitor cells from which the external nose is formed.
Scientists have found that induced pluripotent stem cells from patients with shoulder-blade-facial muscular dystrophy and aronia, turning into placode cells (precursor cells of the sense organs), express the DUX4 protein, which causes cell death, which can later lead to the development of arinia.
The researchers found that in addition to the SMCHD1 gene mutation, the development of aronia requires exposure to a modifying environmental factor. Herpes simplex virus type 1 may be one such factor, scientists believe, since herpesvirus infection enhances DUX4 expression in the knockout SMCHD1 gene of human embryonic stem cells and induced pluripotent stem cells of patients.
The authors of the study emphasized that although the DUX4 protein leads to the development of both diseases, they have not yet been able to find out why nasal aplasia does not occur in the case of muscular dystrophy and, conversely, why muscle weakness does not develop in aronia.
Scientists believe that the identification of drugs that can inhibit the production of the DUX4 protein will allow the development of treatments for these rare diseases.