Objective
ANO5‐related myopathy is an important cause of limb‐girdle muscular dystrophy (LGMD) and hyperCKemia. The main descriptions have emerged from European cohorts, and the burden of the disease worldwide is unclear. We provide a detailed characterization of a large Brazilian cohort of ANO5 patients.
Methods
A national cross‐sectional study was conducted to describe clinical, histopathological, radiological, and molecular features of patients carrying recessive variants in ANO5. Correlation of clinical and genetic characteristics with different phenotypes was studied.
Results
Thirty‐seven patients from 34 nonrelated families with recessive mutations of ANO5 were identified. The most common phenotype was LGMD, observed in 25 (67.5%) patients, followed by pseudometabolic presentation in 7 (18.9%) patients, isolated asymptomatic hyperCKemia in 4 (10.8%) patients, and distal myopathy in a single patient. Nine patients presented axial involvement, including one patient with isolated axial weakness. The most affected muscles according to MRI were the semimembranosus and gastrocnemius, but paraspinal and abdominal muscles, when studied, were involved in most patients. Fourteen variants in ANO5 were identified, and the c.191dupA was present in 19 (56%) families. Sex, years of disease, and the presence of loss‐of‐function variants were not associated with specific phenotypes.
Interpretation
We present the largest series of anoctaminopathy outside Europe. The most common European founder mutation c.191dupA was very frequent in our population. Gender, disease duration, and genotype did not determine the phenotype.
Adult polyglucosan body disease (APBD) represents a complex autosomal recessive inherited neurometabolic disorder due to homozygous or compound heterozygous pathogenic variants in GBE1 gene, resulting in deficiency of glycogen‐branching enzyme and secondary storage of glycogen in the form of polyglucosan bodies, involving the skeletal muscle, diaphragm, peripheral nerve (including autonomic fibers), brain white matter, spinal cord, nerve roots, cerebellum, brainstem and to a lesser extent heart, lung, kidney, and liver cells. The diversity of new clinical presentations regarding neuromuscular involvement is astonishing and transformed APBD in a key differential diagnosis of completely different clinical conditions, including axonal and demyelinating sensorimotor polyneuropathy, progressive spastic paraparesis, motor neuronopathy presentations, autonomic disturbances, leukodystrophies or even pure myopathic involvement with limb‐girdle pattern of weakness. This review article aims to summarize the main clinical, biochemical, genetic, and diagnostic aspects regarding APBD with special focus on neuromuscular presentations.
Background: Adult-onset spinal muscular atrophy (SMA) represents an expanding group of inherited neurodegenerative disorders in clinical practice. Objective: This review aims to synthesize the main clinical, genetic, radiological, biochemical, and neurophysiological aspects related to the classical and recently described forms of proximal SMA. Methods: The authors performed a non-systematic critical review summarizing adult-onset proximal SMA presentations. Results: Previously limited to cases of SMN1-related SMA type 4 (adult form), this group has now more than 15 different clinical conditions that have in common the symmetrical and progressive compromise of lower motor neurons starting in adulthood or elderly stage. New clinical and genetic subtypes of adult-onset proximal SMA have been recognized and are currently target of wide neuroradiological, pathological, and genetic studies. Conclusions: This new complex group of rare disorders typically present with lower motor neuron disease in association with other neurological or systemic signs of impairment, which are relatively specific and typical for each genetic subtype.
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