Adeno-associated virus serotype 9 antibody titers in patients with SMA pre-screened for treatment with onasemnogene abeparvovec -routine care evidence.

Spinal muscular atrophy (SMA) is characterized by progressive weakness of skeletal and respiratory muscles. This study aimed to evaluate the prevalence of pre-existing anti adeno-associated virus serotype 9 antibody (AAV9-Ab) titers among infantile-onset SMA diagnosed infants pre-screened for treatment with AAV9-based onasemnogene abeparvovec, and to explore whether clinical and/or demographic characteristics are correlated with AAV9 Ab test results. This is a retrospective multicenter study of children diagnosed with 5q SMA younger than two years of age. The obtained data included demographic data, SMA type, SMN2 gene copy number, onset date, and results of AAV9-Ab test and of SMA prior treatments. Thirty-four patients were enrolled; six patients had positive results of AAV9-Ab (titer > 1:50) in the initial screening, 15 patients were re-tested for AAV9-Abs, of whom, three patients had seroreverted [1.5-4.5 months] between the two AAV9-Abs tests. One patient had seroconverted (5.5 months after the first AAV9-Abs test). The remaining 11 patients presented matching titer results in the two tests. No demographic/clinical factors were correlated to high AAV9-Abs titers (P > 0.05).We recommend AAV9-Ab re-tests to be performed until the age of 8 months, or, if 1.5 months or more have passed after the initial AAV9-Abs test.

Real-Life Outcome After Gene Replacement Therapy for Spinal Muscular Atrophy: A Multicenter Experience.

BACKGROUND: Onasemnogene abeparvovec-xioi (OA) has been available since 2019 as a gene replacement therapy for individuals with spinal muscular atrophy (SMA) under age two years. We aim to expand upon the sparse knowledge about its safety and clinical efficacy. METHODS: The clinical outcome data of all the individuals with SMA who were treated with gene therapy in four tertiary hospitals in Israel were retrieved and analyzed. RESULTS: The study participants included 25 individuals who received the gene therapy between age 11 days and 23 months and whose median follow-up duration was 18.0 (interquartile range [IQR], 12.4 to 18.3) months. Children's Hospital of Philadelphia Infant Test of Neuromuscular Disorders scores increased by a median (IQR) of 13 (8 to 20) points at the last follow-up compared with baseline. None of the patients experienced regression in motor abilities after gene therapy, which was generally well tolerated. There was gradual improvement in motor function, especially among presymptomatic patients (P ≤ 0.001) whose disease duration was shorter (≤8 months) before receiving gene therapy (P ≤ 0.001) and who did not experience recurrent infections and illnesses in the months following treatment (P ≤ 0.001). CONCLUSIONS: OA was well tolerated and led to favorable functional motor outcomes at six to 24 months after treatment initiation. Better progress in motor function was observed in individuals who received OA earlier and who were presymptomatic, irrespective of the SMN2 copy number or type. Our results further strengthen the clinical efficacy of OA and reinforce the importance of early recognition of SMA via newborn screening programs.

Transcript-Based Diagnosis and Expanded Phenotype of an Intronic Mutation in TPM3 Myopathy.

INTRODUCTION: Congenital myopathies are a broad group of inborn muscle disorders caused by a multitude of genetic factors, often characterized by muscle atrophy and hypotonia. METHODS: Clinical studies, imaging, histology, whole-exome sequencing (WES) and muscle tissue RNA studies. RESULTS: We describe a severe congenital myopathy manifesting at birth with bilateral clubfeet, delayed motor development and hypotonia, becoming evident by 4 months of age. At 3 years of age, the patient had tongue fasciculations, was bedridden, and was chronically ventilated via tracheostomy. Imaging studies demonstrated severe muscle atrophy and, surprisingly, cerebral atrophy; electromyography demonstrated a myasthenic pattern and histological evaluation did not facilitate a definitive diagnosis. Trio WES did not identify a causative variant, except for a non-canonical intronic TPM3 c.118-12G>A variant of uncertain significance. Transcript analysis of muscle tissue from the patient proved the pathogenicity of this homozygous variant, with a 97% reduction in the muscle-specific TPM3.12 transcript. DISCUSSION: This study broadens the phenotypic spectrum of recessive TPM3 disease, highlighting tongue fasciculations and bilateral clubfoot, as well as possibly-related cerebral atrophy. It also shows the importance of a broad approach to genetic analysis and the utility of RNA-based studies, demonstrating efficacy of early genome and transcriptome queries in facilitating rapid and cost-effective diagnosis of congenital myopathies.

Phenotypic variability in patients with unique double homozygous mutations causing variant ataxia telangiectasia.

Ataxia-Telangiectasia (A-T) is a neurodegenerative disease caused by bi-allelic mutations in the Ataxia-Telangiectasia-Mutated (ATM) gene. Complete lack of ATM activity leads to severe A-T and mutations allowing for residual activity cause a milder phenotype, termed variant A-T. There are only sparse data on the variability in phenotypes of variant A-T patients carrying the same mutations. A retrospective study of 15 patients with variant A-T, all double homozygous for the same mutations was conducted. The age of first symptom ranged from 4-180 months, including: truncal ataxia at <18 months of age in 9 patients, ataxia and instability only during fever in one patient, dystonia in one patient and malignancy in 4 patients. Global developmental delay and occulo-motor apraxia were recorded in 4/14 patients. Variant A-T patients with the same mutations in ATM, have variable phenotypes. Environmental, epigenetic, and post translational factors are likely to play a role in creation of the phenotype in variant A-T patients.

The effect of vitamin D administration on vitamin D status and respiratory morbidity in late premature infants.

OBJECTIVE: To assess whether increment of vitamin D daily intake results in improved serum25(OH) vitamin D levels and reduced respiratory morbidity in premature infants. METHODS: A randomized double-blind clinical pilot trial, including preterm infants born at 32 + 6 to 36 + 6 weeks of gestation. The control group received 400 international units (IU) of cholecalciferol daily compared to 800 IU daily in the intervention group. Levels of 25(OH) vitamin D were measured at birth and 6 and 12 months of age. Respiratory morbidity was followed until 1 year of age. RESULTS: Fifty subjects were recruited during the study period; the median measured 25(OH) vitamin D levels in the control vs intervention groups were: 26.5 vs 34 nmol/L (P = .271) at birth, 99 vs 75.5 nmol/L (P = .008) at 6 months and 72.5 vs 75 nmol/L (P = .95) at 12 months of age. Infants with insufficient vitamin D (<75 nmol/L) levels had higher respiratory morbidity. Serum vitamin 25(OH) D is a fair predictor for respiratory symptoms (area under the curve [AUC], 0.697; 95% confidence interval [CI], 0.509-0.885; P = .047) and for recorded acute respiratory illnesses (AUC, 0.745; 95% CI, 0.569-0.922; P = .012). CONCLUSION: Doubling the daily intake of vitamin D in premature infants did not increase serum 25(OH) vitamin D level, due to poor compliance in the intervention group. We found an inverse association between serum 25(OH) vitamin D and respiratory symptoms, indicating vitamin D deficiency is a fair predictor for respiratory morbidity.