Nail-patella (NPS) syndrome is an autosomal dominant disorder caused by mutations in the LMX1B gene and manifests with involvement of kidneys, nails, eyes as well as skeletal musculature. NPS shows some clinical similarities with Emery-Dreifuss muscular dystrophy. However, thus far human muscle tissue has not been analysed in the context of NPS to precisely clarify the muscular involvement in this multi-systemic disease. To study the effects of a missense variant in LMX1B on human skeletal muscle, histological, immunofluorescence and ultra-structural studies were performed on a deltoid muscle biopsy performed at the age of 2 aiming to analyse potential pathologies in muscle fibres in addition to unbiased proteomic profiling to identify dysregulated proteins. Microscopic work-up of the muscle biopsy revealed no striking pathologies, except for some atrophic fibres. The proteomic analyses unveiled a clustered number of dysregulated keratin proteins among the downregulated proteins. Although NPS can also present with a muscular phenotype indicated by muscular weakness of the upper extremities, elevated CK levels and contractures of the elbow joint, there is no evidence of primary muscular involvement due to expression of mutant LMX1B. The examination of human skeletal muscle tissue confirmed the findings from the animal models showing that the skeletal muscle symptoms of NPS may be the result of a developmental disorder of the extremities that leads to impaired muscle mobilisation.

Skeletal muscle laminopathies (SMLs) are rare disorders characterized by skeletal muscle involvement caused by mutations in LMNA gene. To date, the natural history of SMLs has not been clearly elucidated. Through a 2-year prospective study, we aimed to describe the natural history of SMLs. We enrolled 26 SMLs patients, assessed with: North Star Ambulatory Assessment scale (NSAA), timed tests, manual muscle testing, joint range of motion, six-minutes walking test (6MWT); respiratory evaluation including forced vital capacity (FVC) and forced expiratory volume at 1 second (FEV1); individualized neuromuscular quality of life (INQoL). Muscular performance with the aforementioned tools significantly correlated with phenotypes at the baseline, showing the worse outcome in those with autosomal dominant Emery-Dreifuss muscular dystrophy as compared to limb girdle phenotype. NSAA score significantly (p = 0.0005) worsened during the 2-year follow-up. Moreover, the respiratory function through FVC and FEV1 significantly (p = 0.0086 and p = 0.0290, respectively) deteriorated over the follow-up period. 6MWT, INQoL and timed tests did not significantly change, as well as ankle, knee, and elbow contractures. This study showed a slow progression of motor and respiratory function in SMLs patients over a period of 2 years.

Emery-Dreifuss muscular dystrophy type 2 (EDMD2) is a rare autosomal dominant neuromuscular disorder caused by LMNA gene mutations and characterized by progressive skeletal muscle weakness and significant cardiac involvement. We report the case of a 45-year-old woman who presented with sudden-onset, left-sided hemiparesis and dysarthria. Initial imaging was unremarkable, and symptoms transiently improved, suggesting a transient ischemic attack. However recurrent deficits led to the identification of right middle cerebral artery occlusion and new-onset atrial fibrillation. Mechanical thrombectomy was successfully performed. Subsequent cardiac evaluation revealed dilated cardiomyopathy with moderately depressed systolic function and segmental wall motion abnormalities, although coronary arteries were normal. Cardiac magnetic resonance imaging demonstrated myocardial fibrosis with late gadolinium enhancement in the subendocardial and mid-wall regions, suggestive of genetic cardiomyopathy. A neurological examination noted lordotic posture, waddling gait, positive Gowers' sign, generalized proximal muscle atrophy, and flaccid hyporeflexic tetraparesis. Electromyography confirmed a proximal myopathy. The patient reported limb weakness since her twenties. Family history was significant for similar neuromuscular and cardiac symptoms. Genetic testing identified a heterozygous LMNA missense variant (ClinVar ID: 804298), confirming the diagnosis of EDMD2. Despite the implantation of a cardiac resynchronization therapy defibrillator and optimal medical management, she experienced recurrent ventricular tachyarrhythmias, necessitating listing for heart transplantation. This case highlights the diagnostic challenges of EDMD2, particularly when the initial presentation is ischemic stroke, a rare manifestation of this genetic myopathy. It underscores the importance of a multidisciplinary approach for early diagnosis and management to improve the outcomes of this rare but impactful disorder.

Inherited lipodystrophies are a group of rare diseases defined by severe reduction in adipose tissue mass and classified as generalized or partial. We report a non-familial (sporadic) case of partial lipodystrophy caused by a novel genetic mechanism involving closely linked de novo pathogenic variants in the LMNA gene. A female adult with partial lipodystrophy and her parents were evaluated for gene variants across the exome under different mendelian inheritance models (autosomal dominant, recessive, compound heterozygous, and X-linked) to find pathogenic variants. Body composition was assessed via dual-energy X-ray absorptiometry (DXA). The patient showed absence of adipose tissue in the limbs; preservation of adiposity in the face, neck, and trunk; muscular hypertrophy, hypertriglyceridemia and insulin resistance. DXA revealed a fat mass of 15.4%, with android-to-gynoid ratio, trunk/limb, and trunk/leg ratios exceeding the published upper limits of 90% reference intervals. Two heterozygous missense de novo pathogenic variants in cis within the LMNA gene were found in the proband: p.Y481H and p.K486N (NP_733821.1). These variants have functional effects and were reported in inherited Emery-Dreifuss muscular dystrophy 2 (p.Y481H) and familial partial lipodystrophy type 2 (p.K486N). Molecular modeling analyses provided additional insights into the protein instability conferred by these variants in the lamin A/C Ig-like domain. In a case of sporadic partial lipodystrophy, we describe two concurrent de novo pathogenic variants within the same gene (LMNA) as a novel pathogenic mechanism. This finding expands the genetic and phenotypic spectrum of partial lipodystrophy and laminopathy syndromes.

Muscular dystrophy encompasses a group of genetic conditions with progressive muscle damage and weakness. Duchenne muscular dystrophy (DMD) and Becker muscular dystrophy (BMD) are X-linked recessive disorders that affect the production of the protein dystrophin. Emery-Dreifuss muscular dystrophy (EDMD) is typically an X-linked-recessive disorder involving the gene that codes for emerin. Facioscapulohumeral muscular dystrophy and oculopharyngeal muscular dystrophy (OPMD) are both autosomal dominant disorders. Although commonly mistaken as a condition in which patients are susceptible to malignant hyperthermia with volatile inhalational anesthetics, muscular dystrophy is more closely associated with rhabdomyolysis. Providers developing an anesthetic plan for dental patients with muscular dystrophy must take into consideration the patient's baseline cardiac and pulmonary function as well as the potential for abnormalities. Nondepolarizing neuromuscular blocker use is safe but likely to result in prolonged skeletal muscle relaxation. Succinylcholine and volatile anesthetics are generally contraindicated due to the risks of rhabdomyolysis and hyperkalemia with subsequent ventricular fibrillation, cardiac arrest, and death if left untreated. In-depth understanding of the more commonly encountered forms of muscular dystrophy is vital to providing safe and effective ambulatory anesthesia care for patients undergoing dental treatment outside the traditional hospital operating room setting.