Pilot study of population-based newborn screening for spinal muscular atrophy in New York state.

PurposeTo determine feasibility and utility of newborn screening for spinal muscular atrophy (SMA) in New York State.MethodsWe validated a multiplex TaqMan real-time quantitative polymerase chain reaction assay using dried blood spots for SMA. From January 2016 to January 2017, we offered, consented, and screened 3,826 newborns at three hospitals in New York City and tested newborns for the deletion in exon 7 of SMN1.ResultsNinety-three percent of parents opted in for SMA screening. Overall the SMA carrier frequency was 1.5%. We identified one newborn with a homozygous SMN1 deletion and two copies of SMN2, which strongly suggests the severe type 1 SMA phenotype. The infant was enrolled in the NURTURE clinical trial and was first treated with Spinraza at age 15 days. She is now age 12 months, meeting all developmental milestones, and free of any respiratory issues.ConclusionOur pilot study demonstrates the feasibility of population-based screening, the acceptance by families, and the benefit of newborn screening for SMA. We suggest that SMA be considered for addition to the national recommended uniform screening panel.

Rasch analysis of the Pediatric Evaluation of Disability Inventory-computer adaptive test (PEDI-CAT) item bank for children and young adults with spinal muscular atrophy.

INTRODUCTION: In this study we evaluated the suitability of a caregiver-reported functional measure, the Pediatric Evaluation of Disability Inventory-Computer Adaptive Test (PEDI-CAT), for children and young adults with spinal muscular atrophy (SMA). METHODS: PEDI-CAT Mobility and Daily Activities domain item banks were administered to 58 caregivers of children and young adults with SMA. Rasch analysis was used to evaluate test properties across SMA types. RESULTS: Unidimensional content for each domain was confirmed. The PEDI-CAT was most informative for type III SMA, with ability levels distributed close to 0.0 logits in both domains. It was less informative for types I and II SMA, especially for mobility skills. Item and person abilities were not distributed evenly across all types. CONCLUSIONS: The PEDI-CAT may be used to measure functional performance in SMA, but additional items are needed to identify small changes in function and best represent the abilities of all types of SMA. Muscle Nerve 54: 1097-1107, 2016.

Cross-sectional, quantitative analysis of motor function in females with HNRNPH2-related disorder.

AIMS: To describe the gross motor function of individuals with HNRNPH2-related disorder (OMIM 300986, Mental Retardation, X-linked, Syndrome, Bain Type; MRXSB) and determine the associations between clinician-measured motor function and caregiver-reported mobility scores. METHODS: Developmental histories of 17 female participants with HNRNPH2-related disorder (mean age 11.2 years, range 2.7-37.1 years) with various genotypes within and adjacent to the nuclear localization sequence (NLS) were analyzed. Participants performed the Gross Motor Function Measure-88 (GMFM-88) and caregivers completed developmental histories and the Pediatric Evaluation of Disability Inventory-Computer Adaptive Test (PEDI-CAT). RESULTS: All participants had measurable and quantifiable motor impairments. A strong positive correlation between the clinician-measured GMFM-88 total score and the caregiver-reported PEDI-CAT mobility domain score was established. Motor deficits were noted more often in individuals who were nonverbal. The 2 participants with genotypes adjacent to the NLS appear to have milder motor phenotypes. CONCLUSIONS: The GMFM-88 and PEDI-CAT are useful and feasible measures of mobility in individuals with HNRNPH2-related disorders. Convergent validity was established between the clinician-measured GMFM-88 raw scores and caregiver-reported PEDI-CAT mobility domain scores. Factors including verbal status and genotype may impact motor abilities.

Detailed Clinical and Psychological Phenotype of the X-linked HNRNPH2-Related Neurodevelopmental Disorder.

OBJECTIVE: To expand the clinical phenotype of the X-linked HNRNPH2-related neurodevelopmental disorder in 33 individuals. METHODS: Participants were diagnosed with pathogenic or likely pathogenic variants in HNRNPH2 using American College of Medical Genetics and Genomics/Association of Molecular Pathology criteria, largely identified via clinical exome sequencing. Genetic reports were reviewed. Clinical data were collected by retrospective chart review and caregiver report including standardized parent report measures. RESULTS: We expand our clinical characterization of HNRNPH2-related disorders to include 33 individuals, aged 2-38 years, both females and males, with 11 different de novo missense variants, most within the nuclear localization signal. The major features of the phenotype include developmental delay/intellectual disability, severe language impairment, motor problems, growth, and musculoskeletal disturbances. Minor features include dysmorphic features, epilepsy, neuropsychiatric diagnoses such as autism spectrum disorder, and cortical visual impairment. Although rare, we report early stroke and premature death with this condition. CONCLUSIONS: The spectrum of X-linked HNRNPH2-related disorders continues to expand as the allelic spectrum and identification of affected males increases.

Lack of effect on ambulation of dalfampridine-ER (4-AP) treatment in adult SMA patients.

SMA is a genetically determined motor system disorder that results in muscle weakness, selective motor neuron death, muscle atrophy, and impaired functional mobility. In SMA model systems, long-term treatment with 4-aminopyridine (4-AP) has been shown to improve motor function. To assess tolerability and preliminary efficacy of 4-AP on walking ability, endurance and EMG in adult ambulatory SMA patients, we conducted a double blind, placebo control, crossover pilot study with dalfampridine (4-AP, 10 mg BID). The study is comprised of a short-term (2 weeks) treatment arm with 1-week washout and a long-term (6 weeks) treatment arm with a 2-week washout. The primary outcome measure, for which the study was powered, was the 6 min walk test (6MWT, distance and percent fatigue); secondary outcome measures were the Hammersmith Functional Motor Scale Expanded (HFMSE), Manual Muscle Testing (MMT), Myometry with Hand held Dynamometry, HHD) and Quantitative Gait Analyses. We performed electrophysiology, including CMAP and H-reflex, during the short-term treatment trial. The mean age of the 11 participants enrolled was 37.7 ±â€¯11.9 years; 54.5% were male. Dalfampridine was safe and well tolerated and no patient suffered a serious adverse event related to treatment. We observed no statistically significant positive effects of dalfampridine treatment on our primary functional motor outcome (6MWT distance, fatigue). Dalfampridine had a positive effects on H-reflex and H/M ratio but not on CMAP amplitude. The effect on the H-reflex is of interest, as it suggests dalfampridine may enhance neuronal activity, an effect observed in SMA Drosophila and mouse models at doses (mg/kg) not recommended for clinical use. Larger studies with dalfampridine in SMA patients are needed to confirm our findings, especially in light of studies in other populations showing drug effects in only a subset of patients.