Seroprevalence of Adeno-Associated Virus Neutralizing Antibodies in Males with Duchenne Muscular Dystrophy

Adeno-associated virus (AAV)-based gene therapies are emerging strategies in Duchenne muscular dystrophy (DMD) treatment. Exposure to wild-type AAV can lead to development of neutralizing antibodies (NAbs) and blocking of AAV transduction, thereby limiting the delivery of AAV vector-based gene therapy. Therefore, it is imperative to check for the presence of AAV NAbs in a patient who is a candidate for gene therapy. We prospectively enrolled 101 genetically confirmed males with DMD (median age 11 years, 48% ambulatory and 59% on steroids) and performed AAV neutralization assays against AAV2, AAV8, AAV9, and AAVrh74 serotypes. The serotype analysis showed that AAV9 (36%) and AAVrh74 (32%) seroprevalence was lower compared with AAV2 (56%) and AAV8 (47%). Interestingly, age was not correlated with NAb titer for any of the capsids. NAb responses were observed at a higher frequency in African American participants and at a lower frequency in Caucasian participants for all four serotypes. Further analysis showed no significant differences in NAb titers regardless of serotype and whether participants were taking steroids or not. Finally, we observed higher AAV8, AAV9, and AAVrh74 seroprevalence and significantly higher AAV2 and AAV8 NAb titers in participants who were ambulatory compared with nonambulatory participants. Overall, these data identify AAV9 and AAVrh74 as the two serotypes with lower pre-existing NAb titers in this study's cohort of 101 males with DMD, possibly showing their utility in future gene therapy applications in treatment of this cohort of patients with DMD.

Acute Flaccid Myelitis: A Single Pediatric Center Experience From 2014 to 2019

BACKGROUND

Acute flaccid myelitis has emerged as the leading cause of acute flaccid paralysis in children. Acute flaccid myelitis leads to significant physical disability; hence, objective outcome measures to study disease severity and progression are desirable. In addition, nerve transfer to improve motor function in affected children needs further study.

METHODS

Retrospective study of acute flaccid myelitis subjects managed at Children's Healthcare of Atlanta from August 2014 to December 2019. Clinical, electromyography and nerve conduction study, neuropsychological functional independence (WeeFIM), and nerve transfer data were reviewed.

RESULTS

Fifteen children (11 boys and 4 girls) mean age 5.1±3.2 years (range 14 months to 12 years) were included. All subjects (n = 15) presented with severe asymmetric motor weakness and absent tendon reflexes. Motor nerve conduction study of the affected limbs in 93% (n = 14) showed absent or markedly reduced amplitude. Ten patients received comprehensive inpatient rehabilitation and neuropsychological evaluation. Admission and discharge WeeFIM scores showed deficits most consistent and pronounced in the domains of self-care and mobility. Multiple nerve transfer surgery was performed on 13 limbs (9 upper and 4 lower extremities) in 6 children. Postsurgery (mean duration of 10.4 ± 5.7 months) follow-up demonstrated improvement on active movement scale (AMS) in 4 subjects.

CONCLUSION

Acute flaccid myelitis affects school-age children with asymmetric motor weakness, absent tendon reflexes, and reduced or absent motor amplitude on nerve conduction study. Comprehensive rehabilitation and nerve transfer led to improvement in motor function on neuropsychology WeeFIM and AMS scores.

Head injury does not alter disease progression or neuropathologic outcomes in ALS

OBJECTIVES

To study the effects of head injury on disease progression and on neuropathologic outcomes in amyotrophic lateral sclerosis (ALS).

METHODS

Patients with ALS were surveyed to obtain head injury history, and medical records were reviewed. Linear regression was performed to determine if head injury was a predictor for mean monthly decline of Amyotrophic Lateral Sclerosis Functional Rating Scale-revised (ALSFRS-R), while controlling for confounders. Head injury history was obtained from family members of ALS autopsy cases. The frequency of tau proteinopathy, brain TDP-43 inclusions, and pathologic findings of Alzheimer disease (AD) were examined in ALS cases with head injury compared to cases without. Logistic regression was performed with each neuropathologic diagnosis as an outcome measure and head injury as a predictor variable.

RESULTS

No difference was seen in rate of decline of the ALSFRS-R between patients with head injury (n = 24) and without (n = 76), with mean monthly decline of -0.9 for both groups (p = 0.18). Of 47 ALS autopsy cases (n = 9 with head injury, n = 38 without), no significant differences were seen in the frequency of tau proteinopathy (11% with head injury; 24% without), TDP-43 in the brain (44% with head injury; 45% without), or AD pathology (33% with head injury; 26% without). Independent logistic regression models showed head injury was not a predictor of tau pathology (p = 0.42) or TDP-43 in the brain (p = 0.99).

CONCLUSIONS

Head injury was not associated with faster disease progression in ALS and did not result in a specific neuropathologic phenotype. The tau pathology described with chronic traumatic encephalopathy was found in ALS autopsy cases both with and without head injury.