▣ 1.8 Hereditary inclusion body myopathy (hIBM).

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⧈ As these muscle diseases were being discovered, many of them had very similar symptoms. At first, it was believed that several of these diseases were related to each other. As time and research went on, it was discovered that although the conditions looked very similar, they have different causes and are different diseases. An example of this is hereditary inclusion body myopathy (hIBM). It was initially believed that it was related directly to IBM, but it is now understood that there are a group of myopathy diseases caused by genetic mutations and that these diseases are not related to IBM. There still is confusion because the names are very similar.

⚀ Hereditary inclusion body myopathy refers to a group of very rare inherited disorders; passed on from parents to children. Note that these diseases are called myopathy (myopathies) and their characteristics are different from inclusion body myositis, but at this point, these various myopathies are still lumped together with inclusion body myositis.

⚀ "The hIBM diseases lack the two main characteristic features of IBM: its distinctive pattern of muscle weakness and the presence of muscle histological immune cell infiltration" (Greenberg, 2019).

⚀ Greenberg (2019) points out that it is a mistake to think IBM and hIBM reflect the same pathophysiological process that can either occur sporadically or be inherited: "IBM" is an entirely different disease than the group of diseases known as hereditary inclusion body myopathies, but often abbreviated as "hIBM."

⚀ The different forms of hereditary inclusion body myopathy are caused by mutations in different genes that can be passed from generation to generation. One example is GNE myopathy. Other examples are Inclusion body myopathy with early-onset Paget disease and frontotemporal dementia and Inclusion body myopathy 3.