Glucose and lipid metabolism disorders in children and adolescents with spinal muscular atrophy types 2 and 3

The endocrine manifestations of adults with spinal muscular atrophy

INTRODUCTION/AIMS

Changes in body composition in patients with spinal muscular atrophy (SMA) can cause endocrine abnormalities that are insufficiently studied in adults. We aimed to assess the endocrine profile in a cohort of adults with SMA. Second, we compared body composition and endocrine profiles between nonambulatory and ambulatory patients and between different types of SMA.

METHODS

The cross-sectional study included 29 SMA patients (18 [62.1%] males and 11 [37.9%] females) of median age 44 (IQR 30-51.5) years with type 2, 3, or 4. Body composition was measured by bioimpedance. Morning blood samples were drawn for glycated hemoglobin (HbA1c), lipid profile, testosterone, cortisol, and insulin-like growth factor-1 (IGF-1). Blood glucose, insulin, and beta-hydroxybutyrate (BHB) were measured during a 75 g oral glucose tolerance test. The homeostatic model assessment for insulin resistance index was calculated.

RESULTS

In total, 75.9% of patients had increased fat mass (FM), with 51.7% having an increase despite normal body mass index. Ambulation was the most important discriminating factor of body composition. 93.1% of patients had metabolic abnormalities, including hyperglycemia, insulin resistance, and dyslipidemia. Increased BHB, a marker of ketosis, was present in more than a third of patients. Functional hypogonadism was present in half of male patients. Testosterone and IGF-1 negatively correlated with FM.

DISCUSSION

Adult patients with SMA had abnormal body composition and highly prevalent metabolic disturbances that might increase cardiometabolic risk. Because treatments have modified the course of SMA, it is important to investigate whether these observations translate into clinically relevant outcomes.

Glucose and Lipid Metabolism Disorders in Adults with Spinal Muscular Atrophy Type 3

BACKGROUND

Spinal muscular atrophy type 3 (juvenile SMA, Kugelberg-Welander disease) is a genetic disease caused by changes in the survival motor neuron 1 (SMN) gene. However, there is increasing evidence of metabolic abnormalities in SMA patients, such as altered fatty acid metabolism, impaired glucose tolerance, and defects in the functioning of muscle mitochondria. Given that data in the literature are scarce regarding this subject, the purpose of this study was to estimate the prevalence of glucose and lipid metabolism disorders in adult patients with SMA type 3.

METHODS

We conducted a cross-sectional study of 23 adult patients with SMA type 3 who underwent a comprehensive evaluation, including a physical examination, biochemical analysis, and an oral glucose tolerance test during 2020-2023.

RESULTS

At least one lipid abnormality was observed in 60.8% of patients. All four lipid parameters were atypical in 4.3% of patients, three lipid parameters were abnormal in 21.7% of patients, and two lipid parameters were altered in 8.7% patients. A total of 91.3% of SMA3 patients met the HOMA-IR criteria for insulin resistance, with 30.43% having impaired glucose tolerance. None of the patients met the criteria for a diagnosis of overt DM2.

CONCLUSIONS

The prevalence of dyslipidemia and altered glucose metabolism in our study sets apart the adult population with SMA3 from the general population, confirming a significant interplay between muscle, liver, and adipose tissue. Ensuring metabolic care for aging patients with SMA 3 is crucial, as they are vulnerable to metabolic derangements and cardiovascular risks.

Metabolic syndrome is common in adults with 5q-spinal muscular atrophy and impacts quality of life and fatigue

INTRODUCTION/AIMS

Spinal muscular atrophy (SMA) is a multisystem disorder. We assessed metabolic syndrome (MetS) prevalence in adults with SMA and its association with motor function, quality of life (QoL), fatigue, and depression.

METHODS

MetS was diagnosed using 2009 consensus criteria. Hammersmith Functional Motor Scale Expanded (HFMSE), Revised Upper Limb Module (RULM), Fatigue Severity Scale (FSS), Beck Depression Inventory (BDI), and 36-Item Short Form Health Survey (SF-36) were recorded and correlations between muscle function, depression, fatigue, QoL, and MetS were analyzed.

RESULTS

We included 36 individuals (18 males; mean age: 38.7 ± 14.6 years). MetS was present in 25.0%. The most common component of MetS was central obesity (69.7%). Nearly half of the SMA individuals exhibited at least one abnormal lipid level result. Individuals with MetS more frequently were SMA type 3 (77.8% vs. 37.0%, p = .02) and had higher levels of fatigue (48.4 ± 6.7 vs. 39.5 ± 11.6, p = .03) than those without MetS. No associations of the presence of MetS with ambulatory status or HFMSE/RULM scores were observed. SMA individuals with MetS scored significantly lower in mental and social domains of QoL and total SF-36 score (p = .04). We observed weak to moderate correlations between the presence of MetS and SMA type, presence of comorbidities, QoL, and fatigue.

DISCUSSION

The frequency of MetS was modestly higher among adults with SMA than in the general population, particularly in SMA type 3. MetS was associated with reduced QoL and increased fatigue. Larger studies are needed to fully understand the significance of MetS in adults with SMA.

A transcriptomics-based drug repositioning approach to identify drugs with similar activities for the treatment of muscle pathologies in spinal muscular atrophy (SMA) models

Spinal muscular atrophy (SMA) is a genetic neuromuscular disorder caused by the reduction of survival of motor neuron (SMN) protein levels. Although three SMN-augmentation therapies are clinically approved that significantly slow down disease progression, they are unfortunately not cures. Thus, complementary SMN-independent therapies that can target key SMA pathologies and that can support the clinically approved SMN-dependent drugs are the forefront of therapeutic development. We have previously demonstrated that prednisolone, a synthetic glucocorticoid (GC) improved muscle health and survival in severe Smn-/-;SMN2 and intermediate Smn2B/- SMA mice. However, long-term administration of prednisolone can promote myopathy. We thus wanted to identify genes and pathways targeted by prednisolone in skeletal muscle to discover clinically approved drugs that are predicted to emulate prednisolone's activities. Using an RNA-sequencing, bioinformatics, and drug repositioning pipeline on skeletal muscle from symptomatic prednisolone-treated and untreated Smn-/-; SMN2 SMA and Smn+/-; SMN2 healthy mice, we identified molecular targets linked to prednisolone's ameliorative effects and a list of 580 drug candidates with similar predicted activities. Two of these candidates, metformin and oxandrolone, were further investigated in SMA cellular and animal models, which highlighted that these compounds do not have the same ameliorative effects on SMA phenotypes as prednisolone; however, a number of other important drug targets remain. Overall, our work further supports the usefulness of prednisolone's potential as a second-generation therapy for SMA, identifies a list of potential SMA drug treatments and highlights improvements for future transcriptomic-based drug repositioning studies in SMA.

Acetaminophen treatment in children and adults with spinal muscular atrophy: a lower tolerance and higher risk of hepatotoxicity

Acute liver failure has been reported sporadically in patients with spinal muscular atrophy (SMA) and other neuromuscular disorders with low skeletal muscle mass receiving recommended dosages of acetaminophen. It is suggested that low skeletal muscle mass may add to the risk of toxicity. We aimed to describe the pharmacokinetics and safety of acetaminophen in patients with SMA. We analyzed acetaminophen metabolites and liver biomarkers in plasma from SMA patients and healthy controls (HC) every hour for six or eight hours on day 1 and day 3 of treatment with therapeutic doses of acetaminophen. Twelve patients with SMA (six adults and six children) and 11 HC participated in the study. Adult patients with SMA had significantly lower clearance of acetaminophen compared to HC (14.1 L/h vs. 21.5 L/h). Formation clearance of acetaminophen metabolites, glucuronide, sulfate, and oxidative metabolites were two-fold lower in the patients compared to HC. The liver transaminases and microRNAs increased nine-fold in one adult SMA patient after two days of treatment. The other patients and HC did not develop abnormal liver biomarkers. In this study, patients with SMA had lower clearance and slower metabolism of acetaminophen, and one patient developed liver involvement. We recommend giving 15 mg/kg/dose to SMA adults (with a maximum of 4000 mg/day) and monitoring standard liver biomarkers 48 h after first-time treatment of acetaminophen.

Metabolic assessment in children with neuromuscular disorders shows risk of liver enlargement, steatosis and fibrosis

AIM

The aim of this study was to conduct a metabolic and nutritional assessment of children with neuromuscular disorders, including the investigation of the liver and bone mineral density.

METHODS

In this observational study, we included 44 children with neuromuscular disorders. The nutritional status, bone health and liver were assessed by ultrasound, transient elastography, dual X-ray absorptiometry scan, blood samples, anthropometric measurements and 3-day diet registration.

RESULTS

Liver involvement was found in 31.0%: liver enlargement in 7.1%, steatosis in 4.8%, fibrosis in 14.3% and liver enlargement together with steatosis or fibrosis was found in 4.8%. These changes were found in 9/23 patients with Duchenne muscular dystrophy, 4/9 patients with spinal muscular atrophy type II and 0/12 patients with other neuromuscular diagnoses. Low bone mineral density was found in 44.0% of the patients, though the majority used daily vitamin D and calcium supplements. Vitamin D insufficiency or deficiency was found in 22.6%.

CONCLUSION

The metabolic assessment in children with neuromuscular disorders shows an increased risk of liver enlargement, steatosis and fibrosis. Possible causes are obesity, decreased mobility, low skeletal muscle mass and for a subgroup the use of glucocorticoids. The findings suggest that monitoring liver function should be part of the nutritional assessment in patients with neuromuscular disorders.

Mitochondrial Dysfunction in Spinal Muscular Atrophy

Spinal muscular atrophy (SMA) is a devastating neuromuscular disorder caused by recessive mutations in the SMN1 gene, globally affecting ~8-14 newborns per 100,000. The severity of the disease depends on the residual levels of functional survival of motor neuron protein, SMN. SMN is a ubiquitously expressed RNA binding protein involved in a plethora of cellular processes. In this review, we discuss the effects of SMN loss on mitochondrial functions in the neuronal and muscular systems that are the most affected in patients with spinal muscular atrophy. Our aim is to highlight how mitochondrial defects may contribute to disease progression and how restoring mitochondrial functionality may be a promising approach to develop new therapies. We also collected from previous studies a list of transcripts encoding mitochondrial proteins affected in various SMA models. Moreover, we speculate that in adulthood, when motor neurons require only very low SMN levels, the natural deterioration of mitochondria associated with aging may be a crucial triggering factor for adult spinal muscular atrophy, and this requires particular attention for therapeutic strategies.

Serum leptin levels in children and adolescents with spinal muscular atrophy types 2 and 3✰

AIM

It has been reported that in patients with spinal muscular atrophy (SMA), lower levels of motor function are associated with hyperleptinemia. Additionally, hyperleptinemia has been found to be more frequent in underweight SMA patients. Therefore, we aimed to analyze serum leptin levels in patients with SMA.

METHOD

This was a cross-sectional study of pediatric patients (2-19 years old) with SMA types 2 and 3. The investigations included anthropometric measurements, assessment of pubertal status, motor function evaluation using the Hammersmith Functional Motor Scale - Expanded (HFMSE), and serum leptin levels.

RESULTS

In total, 37 patients (22 with type 2 and 15 with type 3 SMA) were included in the study. The male-to-female ratio was 1:1.3 and 62.2% of patients were prepubertal. No statistically significant correlation was found between the HFMSE score and leptin levels, r_s(35) = 0.24, p = 0.15. There was, however, a strong positive relationship between the body mass index (BMI) z-score and leptin levels, r_s(35) = 0.87, p < 0.001.

CONCLUSION

Serum leptin levels do not seem to be a useful marker of disease severity in children and adolescents with types 2 and 3 SMA. As in the general pediatric population, leptin levels are strongly correlated with BMI, which is a surrogate measure of body fat.

Association between serum zinc level and lipid profiles in children with spinal muscular atrophy

Background and aims

Children with spinal muscular atrophy (SMA) have a high rate of dyslipidaemia, which is a risk factor of vital importance for cardiovascular diseases in adulthood. Studies have demonstrated that the serum zinc level is associated with lipid profiles in the general population as well as in individuals diagnosed with obesity or diabetes. The purpose of this study was to evaluate the relationship between serum zinc level and lipid profiles in children with SMA.

Methods

This cross-sectional study was launched in a tertiary children's medical center in China and involved pediatric patients with SMA under the management of a multidisciplinary team of outpatient services from July 2019 to July 2021. Anthropometric information, general clinical data, serum zinc level, lipid profiles, and body composition data were collected. Multivariate analysis was used for a thorough inquiry on the association between the serum zinc level and lipid profiles.

Results

Among the 112 patients with SMA [median (IQR) age 5.54 years (2.75–8.29), 58.04% female], who fulfilled the inclusion criteria of the study, dyslipidaemia was detected in 60 patients (53.57%). Based on multivariable linear regression, serum zinc level was positively associated with high-density lipoprotein cholesterol (HDL-C; β = 1.63, 95% CI = 0.44–3.22) and apolipoprotein A1 (APO A1; β = 2.94, 95% CI = 0.03–5.85) levels, independently of age, sex, type, activity, percentage of body fat, and body mass index. As the serum zinc level increased by 10 μmol/L, the risk of low APO A1 levels decreased by 35% (OR = 0.65, 95% CI = 0.44–0.97) according to multivariable logistic regression analyses.

Conclusion

Serum zinc concentration was positively correlated with HDL-C and APO A1 levels among children with SMA. We suggest measures to correct the lower level of serum zinc to improve HDL-C and APO A1 levels.

The alteration of left ventricular strain in later-onset spinal muscular atrophy children

Background

Patients with spinal muscular atrophy (SMA) may suffer from multisystem injury, including an impaired cardiovascular system. However, M-mode echocardiography, the current dominant echocardiographic modality, is limited in the detection of myocardial injury. We considered the use of left ventricular strain imaging in detecting myocardial injury and explored the serum lipid profile related to cardiovascular disease in later-onset SMA children.

Methods

A case-control study involving 80 patients with later-onset SMA and 80 age-, gender-, and body surface area-matched control children was conducted in a single tertiary pediatric hospital in China. Data on the left ventricular strain measured using two-dimensional speckle tracking echocardiography, left ventricular function parameters assessed by M-mode echocardiography, and serum lipid profile of these two groups were retrospectively collected for differential analysis.

Results

The mean age of the 80 SMA patients were (6.87 ± 2.87) years, of which 46 were type 2 and 34 were type 3 patients. The global longitudinal strain (GLS) of the SMA group (−18.7 ± 2.9%, p < 0.001) was lower than that of the control group; the time to peak longitudinal strain (TTPLS) of the SMA group (22.9 ± 13.6 ms, p < 0.001) was higher than that of the control group, while left ventricular ejection fraction (LVEF) and left ventricular fractional shortening (LVFS), measured by the Teichholz method of M-mode echocardiography, showed no significant differences between the two groups. In addition, independent indicators for cardiovascular risk, including total cholesterol (TC)/HDL, low-density lipoprotein (LDL)/HDL, and Apo B/Apo A1 levels, were higher in SMA children than in the control group.

Conclusion

Compared with healthy controls, later-onset SMA children presented with reduced GLS and prolonged TTPLS while the LVEF and LVFS values were within normal range. In particular, whether a reduced GLS or prolonged TTPLS in later-onset SMA compared to the control group can predict the risk of future cardiomyopathy remains to be investigated.

Nutritional, Gastrointestinal and Endo-Metabolic Challenges in the Management of Children with Spinal Muscular Atrophy Type 1

The management of patients with spinal muscular atrophy type 1 (SMA1) is constantly evolving. In just a few decades, the medical approach has switched from an exclusively palliative therapy to a targeted therapy, transforming the natural history of the disease, improving survival time and quality of life and creating new challenges and goals. Many nutritional problems, gastrointestinal disorders and metabolic and endocrine alterations are commonly identified in patients affected by SMA1 during childhood and adolescence. For this reason, a proper pediatric multidisciplinary approach is then required in the clinical care of these patients, with a specific focus on the prevention of most common complications. The purpose of this narrative review is to provide the clinician with a practical and usable tool about SMA1 patients care, through a comprehensive insight into the nutritional, gastroenterological, metabolic and endocrine management of SMA1. Considering the possible horizons opened thanks to new therapeutic frontiers, a nutritional and endo-metabolic surveillance is a crucial element to be considered for a proper clinical care of these patients.

Metabolic Dysfunction in Spinal Muscular Atrophy

Spinal muscular atrophy (SMA) is an autosomal recessive genetic disorder leading to paralysis, muscle atrophy, and death. Significant advances in antisense oligonucleotide treatment and gene therapy have made it possible for SMA patients to benefit from improvements in many aspects of the once devastating natural history of the disease. How the depletion of survival motor neuron (SMN) protein, the product of the gene implicated in the disease, leads to the consequent pathogenic changes remains unresolved. Over the past few years, evidence toward a potential contribution of gastrointestinal, metabolic, and endocrine defects to disease phenotype has surfaced. These findings ranged from disrupted body composition, gastrointestinal tract, fatty acid, glucose, amino acid, and hormonal regulation. Together, these changes could have a meaningful clinical impact on disease traits. However, it is currently unclear whether these findings are secondary to widespread denervation or unique to the SMA phenotype. This review provides an in-depth account of metabolism-related research available to date, with a discussion of unique features compared to other motor neuron and related disorders.