These proteins play an important role in many cellular processes, such as in providing a nuclear scaffold for protein complexes, maintaining nuclear structure, regulating gene expression, and playing roles in signaling pathways.,,, Mutations in the LMNA gene cause a series of rare diseases known as laminopathies, which involve skeletal muscles, cardiac muscles, peripheral nerves and fat tissue., Skeletal muscle disorders caused by mutations in the LMNA gene can manifest as diverse phenotypes, such as LMNA -associated congenital muscular dystrophy (L-CMD), Emery-Dreifuss muscular dystrophy (EDMD), and limb-girdle muscular dystrophy type 1B (LGMD1B).
The cardiomyopathy and conduction defects may result in a high risk of cardiac sudden death.,, LGMD1B is characterized by predominant scapular and pelvic girdle muscle involvement, and the onset age is later than that of EDMD.
It has been demonstrated that patients have a similar pattern of fatty infiltration regardless of whether their phenotype is EDMD or LGMD1B.,,, Our objective was to investigate whether there is a consistent pattern of muscle MRI changes in patients with LMNA mutations related to EDMD, LGMD1B, and L-CMD.
6-14 belonged to the LGMD1B group, with ages ranging from 2.5 to 57.0 years.
In total, 21 patients (four with EDMD, nine with LGMD1B, and eight with L-CMD) underwent thigh muscle MRI [Figure 1], [Figure 2] and [Table 2], [Table 3].
There were only six patients who underwent lower leg muscle MRI, including one with EDMD, four with LGMD1B, and one with L-CMD.
This result was in accordance with previous reports.,, In L-CMD, although the muscle MRI scans showed less fatty infiltration in the vasti muscles in the early stage of the disease, the follow-up MRI revealed fatty infiltration in the vasti muscle, while the rectus femoris was relatively spared, indicating the same muscle involvement pattern as that in EDMD or LGMD1B over the course of disease progression.
We find that fatty infiltration of the vasti muscles is more frequently found in EDMD and LGMD1B patients compared to L-CMD patients, indicating that the vasti muscles are involved in the advanced stage of the disease.
The major forms of LGMD result from mutations in genes encoding constituents of the sarcolemmal dystrophin complex, e.g., laminin (LGMD1B), sarcoglycan (LGMD2C-F), and dysferlin (LGMD2B).
Finally, a manual filtering step was carried out to prioritize relevant genes in the 30 major LGMD genes for LGMD1B, LGMD2CF, and LGMD2B.