Tubulinopathies encompass a spectrum of disorders resulting from variants in genes encoding α- and β-tubulins, the key components of microtubules. While previous studies have linked de novo or dominantly inherited TUBA4A missense variants to neurodegenerative phenotypes, including amyotrophic lateral sclerosis, frontotemporal dementia, spastic ataxia, and recently, an isolated congenital myopathy, the full phenotypic and genotypic spectrum of TUBA4A-related disorders remains incompletely characterised. In this multi-centre study, we identified one previously reported and 12 novel TUBA4A missense variants in 31 individuals from 19 unrelated families. Remarkably, individuals in 17 families presented with a myopathy without any CNS involvement or history of such disease. In the remaining two families, we observed probands with cerebellar ataxia and epilepsy accompanying proximal and axial muscle weakness along with protein aggregation. The coexistence of neuromuscular and neurodegenerative features with protein aggregation defines a multisystem proteinopathy. These two families thus establish the first association between TUBA4A and multisystem proteinopathy. Our cohort exhibited diverse genotypes and inheritance patterns: four families demonstrated autosomal dominant transmission through heterozygous variants in TUBA4A, three probands had recessive inheritance due to homozygous variants, while the respective heterozygous carriers were asymptomatic; five probands carried de novo variants, and nine probands with heterozygous variants were classified as sporadic cases. Clinical phenotypes ranged from mild to severe myopathy, predominantly affecting the axial and paraspinal muscles. We observed a range of disease onset, from congenital to late adulthood. Creatine kinase levels were variable, ranging from normal to highly elevated. Cardiac function remained preserved across the cohort. Muscle biopsies showed heterogenous myopathic changes, including myofibre size variation, nemaline bodies, core-like regions, and internal nuclei. Immunohistochemical analysis revealed protein accumulations positive for TDP-43 (n=2), p62 (n=5), and TUBA4A (n=6). Complementary in silico and in vitro investigations suggested that the identified TUBA4A variants cause significant protein abnormalities and may differentially impact microtubule dynamics. Correlation analyses integrating clinical severity, variant location, and mechanistic readouts further demonstrated that domain specificity within TUBA4A influences both the pattern of muscle involvement and the extent of microtubule disruption. Our findings establish myo-tubulinopathies as distinct clinical entities, encompassing both primary myopathies and multisystem proteinopathies with muscle involvement. This study broadens the phenotypic and genotypic spectrum of TUBA4A-related disorders beyond autosomal dominant or de novo mechanisms and neurodegenerative presentations. These results underscore the importance of considering TUBA4A variants in the differential diagnosis of axial myopathies and multisystem proteinopathies, regardless of central nervous system (CNS) involvement.

SNUPN-related muscular dystrophy or LGMDR29 is a new entity that covers from a congenital or childhood onset pure muscular dystrophy to more complex phenotypes combining neurodevelopmental features, cataracts, or spinocerebellar ataxia. So far, 12 different variants have been described. Here we report the first family with SNUPN-related muscular dystrophy presenting an adult-onset myopathy as well as novel ultrastructural findings. Clinical evaluation, muscle and brain magnetic resonance imaging (MRI), and muscle histopathological and electron microscopy analysis were conducted. Functional studies including protein modelling and interaction, immunofluorescence and splicing analysis were also performed. Two siblings carrying two novel deleterious variants in the SNUPN gene (p.Arg27Cys and p.Cys174Tyr) showed adult-onset proximo-distal and axial muscle weakness with early respiratory involvement. One patient presented with asymptomatic cerebellar atrophy. Muscle MRI identified involvement in the paravertebral, triceps brachii, sartorius and gracilis muscles. The histopathology revealed dystrophic changes and an abnormal pattern of cytoskeletal and myofibrillar proteins, while electron microscopy disclosed the proliferation of granules and vesicles associated with features of nuclear envelope and sarcolemma remodelling. Functional studies showed that SNUPN variants impair snurportin-1 function through reduced binding affinity to importin-β and impaired folding, leading to disturbed nuclear import of small nuclear ribonucleoproteins and downstream splicing. Our work expands the phenotype of SNUPN-related muscular dystrophy and provides more insights into their pathological profile. We advise SNUPN testing in patients with late-onset proximo-distal and axial weakness with early respiratory impairment and features reminding inclusion body myositis (IBM). Granular deposits suggestive of biomolecular condensates perturbed cell organelle traffic and membrane homeostasis, opening new avenues to understand the pathomechanisms involved in this novel disease.

Dystroglycanopathy is a genetically heterogeneous group of rare muscular dystrophies that affect the brain, muscles, and eyes, primarily resulting from impaired glycosylation of α-dystroglycan. In this study, we identify and characterize a novel heterozygous CRPPA gene variant causally associated with α-dystroglycanopathy. We present a case of a 1-year and 5-month-old female with elevated creatine kinase (CK) levels and seizures, along with global developmental delay, microphthalmia, hypotonia, and myasthenia. Notably absent was ocular involvement. The serum CK levels typically fluctuated between 2,356 and 9,555 U/L. Video-electroencephalogram monitoring demonstrated abnormal discharge in the left anterior frontal region. Brain magnetic resonance imaging revealed numerous subcortical cysts in the bilateral cerebellar hemispheres and corpus callosum dysplasia. We performed whole-exome sequencing to identify compound heterozygous mutations in the CRPPA gene [Online Mendelian Inheritance in Man (OMIM): 614643]. The identified mutations include the pathogenic variant c.1251G>A (p. Gln 417=) inherited from father, and the c.1119+2T>G variant inherited from mother. We confirm that c.1119+2T>G was a novel splice-site variant. Based on the clinical manifestations, ancillary tests, and genetic results, the patient was diagnosed with congenital muscular dystrophy with mental retardation (CMD-MR). Levetiracetam effectively controlled the seizures. However, the patient's motor and cognitive impairments remained unaddressed by pharmacological interventions and persisted backward. We present a case of α-dystroglycanopathy caused by a novel splice site variant, c.1119+2T>G, in the CRPPA gene. The patient presented with clinical features characteristic of CMD-MR, thus extending the phenotypic spectrum of α-dystroglycanopathy.

Tubulinopathies encompass a wide spectrum of disorders resulting from variants in genes encoding α- and β-tubulins, the key components of microtubules. While previous studies have linked de novo or dominantly inherited TUBA4A missense variants to neurodegenerative phenotypes, including amyotrophic lateral sclerosis, frontotemporal dementia, hereditary spastic ataxia, and more recently, an isolated report of congenital myopathy, the full phenotypic and genotypic spectrum of TUBA4A-related disorders remains incompletely characterised. In this multi-centre study, we identified 13 novel TUBA4A missense variants in 31 individuals from 19 unrelated families. Remarkably, affected individuals in 17 families presented with a primary axial myopathy without any identified CNS involvement or history of such disease. In the remaining two families, we observed probands with cerebellar ataxia and epilepsy accompanying proximal and axial muscle weakness, establishing the first documented association between TUBA4A variants and multisystem proteinopathy. Our cohort exhibited diverse genotypes and associated inheritance patterns: four families demonstrated autosomal dominant transmission through heterozygous variants in TUBA4A, three probands had homozygous TUBA4A variants, where the biallelic genotype was found to be associated with the disease, and the heterozygous carriers were asymptomatic; five probands carried de novo variants, and nine probands with heterozygous TUBA4A variants were classified as "isolated-sporadic cases" where parental samples were unavailable. Clinical phenotypes ranged from mild to severe myopathy, predominantly affecting the axial and paraspinal muscles. We observed a range of disease onset, from congenital to late adulthood. Creatine kinase levels were also variable, ranging from normal to highly elevated. Cardiac function remained preserved across the cohort. Muscle biopsies revealed a range of pathologies, including myofibre size variation, myofibre atrophy, nemaline bodies, core-like regions, internal nuclei, and endomysial fibrosis. Immunohistochemical staining showed evidence of proteinopathy, with autophagic features and TUBA4A accumulation in patient myofibres. Complementary in silico and in vitro investigations suggested that the identified TUBA4A substitutions cause significant protein abnormalities and may differentially impact microtubule dynamics. Our findings establish myo-tubulinopathies as distinct clinical entities, encompassing both primary myopathies and multisystem proteinopathies with muscle involvement. This study broadens the phenotypic and genotypic spectrum of TUBA4A-related disorders beyond autosomal dominant or de novo mechanisms and neurodegenerative presentations. These results underscore the importance of considering TUBA4A variants in the differential diagnosis of axial myopathies and multisystem proteinopathies, regardless of central nervous system (CNS) involvement. Fukuyama congenital muscular dystrophy (FCMD) is characterized by hypotonia, symmetric generalized muscle weakness, and brain malformations including, classically, cobblestone lissencephaly with cerebral and cerebellar dysplasia. There is a spectrum of severity and mild, typical, and severe phenotypes are recognized. Disease onset typically occurs in early infancy with poor suck/swallow, weak cry, and floppiness. Serum creatine kinase (CK) levels are usually in the thousands (10-60 times higher than normal). Motor development peaks at around age five to six years and thereafter regresses as muscle atrophy progresses. In the typical case, sitting without support or sliding along the floor on the buttocks may be the peak motor function. Deep tendon reflexes are diminished or absent after early infancy. Affected individuals have contractures of the hips, knees, and interphalangeal joints. Later-onset features include a myopathic facial appearance, pseudohypertrophy of the calves and forearms, motor and speech delays, intellectual disability, seizures, ophthalmologic abnormalities including visual impairment and retinal dysplasia, and progressive cardiac involvement after age ten years. Swallowing disturbance occurs in individuals with severe FCMD and in individuals older than age ten years, leading to recurrent aspiration pneumonia and death. The diagnosis of FCMD is established in a proband with biallelic pathogenic variants in FKTN identified by molecular genetic testing. Treatment of manifestations: Physical therapy and stretching exercises, treatment of orthopedic complications; mobility assistance devices such as long leg braces and wheelchairs; use of noninvasive respiratory aids or tracheostomy; prompt treatment of respiratory tract infections; anti-seizure medications; medical and/or surgical treatment for gastroesophageal reflux; gastrostomy tube placement when indicated to assure adequate caloric intake; cardiomyopathy treatment per cardiologist. Surveillance: Monitor gastrointestinal function and for signs/symptoms of gastroesophageal reflux; for orthopedic complications including foot deformities and scoliosis; for myocardial involvement by chest radiography, EKG, and echocardiography in individuals older than age ten years; and respiratory function in individuals with advanced disease. FCMD is inherited in an autosomal recessive manner. If both parents are known to be heterozygous for an FKTN pathogenic variant, each sib of an affected individual has at conception a 25% chance of being affected, a 50% chance of being an asymptomatic carrier, and a 25% chance of being unaffected and not a carrier. Once the FKTN pathogenic variants have been identified in an affected family member, carrier testing for at-risk family members and prenatal/preimplantation genetic testing are possible.

The trafficking protein particle (TRAPP) complex is a multisubunit protein complex that functions as a tethering factor involved in intracellular trafficking. TRAPPC11, a crucial subunit of this complex, is associated with pathogenic variants that cause a spectrum of disease, which can range from a limb girdle muscular dystrophy (LGMD) to developmental disability with muscle disease, movement disorder and global developmental delay (GDD)/intellectual disability (ID), or even a congenital muscular dystrophy (CMD). We reviewed the phenotype of all reported individuals with TRAPPC11-opathies, including an additional Mexican patient with novel compound heterozygous missense variants in TRAPPC11 (c.751 T > C and c.1058C > G), restricted to the Latino population. In these 54 patients muscular dystrophy signs are common (early onset muscle weakness, increased serum creatine kinase levels, and dystrophic changes in muscle biopsy). They present two main phenotypes, one with a slowly progressive LGMD with or without GDD/ID (n = 12), and another with systemic involvement characterized by short stature, GDD/ID, microcephaly, hypotonia, poor speech, seizures, cerebral atrophy, cerebellar abnormalities, movement disorder, scoliosis, liver disease, and cataracts (n = 42). In 6 of them CMD was identified. Obstructive hydrocephaly, retrocerebellar cyst, and talipes equinovarus found in the individual reported here has not been described in TRAPPC11 deficiency. As in previous patients, membrane trafficking assays in our patient showed defective abnormal endoplasmic reticulum-Golgi transport as well as decreased expression of LAMP2, and ICAM-1 glycoproteins. This supports previous statements that TRAPPC11-opathies are in fact a congenital disorder of glycosylation (CDG) with muscular dystrophy.