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.

It is relatively rare to find a significant increase in creatine kinase (CK) related to hypothyroidism through a health examination. This case report describes an asymptomatic adult patient in whom an asymptomatic elevation of serum CK was discovered incidentally during a routine health check. The patient reported no significant muscle weakness, pain, or other classic symptoms of proximal myopathy or hypothyroidism. A comprehensive diagnostic workup was initiated to investigate the common causes of high CK level, including cardiac injury, strenuous exercise, statin use, and inflammatory myopathies, all of which were excluded. Thyroid function tests revealed severe primary hypothyroidism with significantly elevated thyroid-stimulating hormone (TSH; >100 mIU/L) and decreased free thyroxine levels. A diagnosis of hypothyroid myopathy was established. Upon initiation of levothyroxine replacement therapy, the patient's thyroid function normalized, and this was followed by a complete normalization of the serum CK level on subsequent follow-up. This case highlights that hypothyroidism is an important, reversible, notable, and treatable cause of an asymptomatic unexplained CK elevation, particularly in the context of severe biochemical hypothyroidism. It underscores the critical importance of including thyroid function tests in the routine differential diagnosis of any unexplained high CK level, even in the absence of overt clinical myopathic symptoms or recognized signs of hypothyroidism. For clinicians and general practitioners interpreting routine health screening results, this case serves as a vital reminder that a simple thyroid function test can prevent unnecessary and costly investigations and lead to the correct diagnosis and effective treatment. In asymptomatic individuals undergoing routine health screening, an isolated elevation of creatine kinase (CK) may be an early biochemical indicator of underlying hypothyroidism, warranting simple thyroid function testing. This case underscores the public health value of routine biochemical panels that include CK, as they can identify individuals with subclinical endocrine dysfunction before the development of overt clinical disease. For primary care and preventive medicine physicians, integrating thyroid function tests into the initial workup for incidentally discovered hyperCKemia is a cost-effective strategy that can prevent unnecessary specialist referrals and invasive investigations.

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.

Persistent elevation of serum creatine kinase levels (hyperCKemia) as an isolated manifestation presents a diagnostic challenge. Genetic myopathies are frequently involved; however, studies using next-generation sequencing (NGS) in pediatric patients are lacking, and the significance of genetic aberrations remains poorly understood. This study, therefore, aimed to investigate the relevance of NGS and the support of contemporary diagnostic tools in the diagnosis of pediatric asymptomatic hyperCKemia. This was a prospective cohort study enrolling pediatric (0-18 years old) patients meeting the predefined criteria for asymptomatic/paucisymptomatic hyperCKemia, excluding DMD gene deletion/duplication, recruited from a referral center. NGS, muscle MRI, EMG, and muscle biopsies with immunolabeling and inflammatory markers were performed according to a prespecified protocol. Data analysis was performed using descriptive/univariate statistics and Bayesian logistic regression. The series comprised 65 patients (78% male). NGS diagnosis was achieved in 55% of the cohort, with 70% of the pathogenic variants involving 7 genes (DMD, CAPN3, ANO5, DYSF, RYR1, GAA, and CAV3). The diagnostic rate was similar across all age groups; however, the gene profiles varied between the childhood and juvenile groups. EMG yielded myopathic features in 48% of the investigated cases, being predictive for diagnosis (p < 0.05; odds ratio [OR] 13.484, 95% CI 1.358-705.297). MRI showed normal (64%), focal fatty change (26%), or short-tau inversion recovery hyperintensity (10%) profiles, which were not predictive of diagnosis but supported muscle biopsy indications. Muscle biopsy provided a significant diagnostic effect (p < 0.05; OR 0.028, 95% CI 0.001-0.238), contributing to myopathologic features clarifying the variant pathogenicity and identifying inflammatory myopathies. The diagnoses remained inconclusive and unresolved in 14% and 29% of the cohorts, respectively. The diagnostic rate for patients with CK levels below the threshold of 3× was 42%. In multivariate analysis, NGS was the only variable achieving a significant diagnostic effect (β = 9.85, 95% CI 4.65-16.09). NGS, as the primary diagnostic tool for investigating hyperCKemia in the pediatric population, yielded a higher diagnostic rate. However, muscle biopsies are necessary to define variants of uncertain pathogenicity and aid in identifying inflammatory myopathies. EMG and MRI may play a role in hyperCKemia characterization, guiding the decision to perform muscle biopsy. The primary limitation of this study was that not all ancillary tests were performed in all recruited patients owing to ethical restrictions, which lowered the power of the predictive analysis.

Glycerol kinase deficiency (GKD) is a rare X-linked metabolic disorder caused by pathogenic variants in the GK gene. It can be present in either isolated or complex forms and often mimics primary hyperlipidemia, leading to diagnostic challenges and unnecessary treatment. This study aims to highlight the phenotypic variability and diagnostic features of GKD through a case series. We describe three pediatric patients diagnosed with GKD. Two siblings with isolated GKD presented with persistent, asymptomatic hypertriglyceridemia, confirmed by glyceroluria and genetic testing revealing a hemizygous c.213_214delAT (p.Cys72Ter) mutation. The third patient, diagnosed with complex GKD, presented in infancy with multisystem involvement, including immunodeficiency, hypotonia, splenic abscesses, and elevated and creatine kinase levels. Genetic analysis revealed a 6.9 Mb contiguous deletion spanning Xp21.2-Xp11.4. In all cases, elevated triglyceride levels were unresponsive to therapy, and serum samples lacked lipemic appearance. Lipid-lowering treatments were discontinued following diagnosis, with no adverse outcomes. This case series underscores the clinical and genetic heterogeneity of GKD. Urinary glycerol analysis and the absence of serum lipemia are key diagnostic clues. Early recognition is essential to prevent misdiagnosis and guide appropriate management, particularly in treatment-resistant hypertriglyceridemia.