Novel TTN Mutation Causing Severe Congenital Myopathy and Uncertain Association with Infantile Hydrocephalus.

Arthrogryposis multiplex congenita (AMC) is characterized by nonprogressive symmetric contractures of multiple joints with normal intellect and normal systemic examination. AMC is often due to fetal akinesia, which has neurologic, muscular, and connective tissue etiologies. We present a case of AMC due to a variant in the titin (TTN) gene in a term neonate. The infant is homozygous for this variant, c.38442dup, which is predicted to result in a truncated protein (p.Pro12815Thr fs∗37, NM_001267550.2). A literature search (PubMed) failed to find reports of this TTN variant. The variant was classified as pathogenic and submitted to ClinVar. Titin is the body's largest protein, expressed in skeletal and cardiac muscles and encoded by the TTN gene. Due to its large size (364 exons), the TTN gene has been difficult to sequence; the number of variants in the TTN gene and the spectrum of titinopathies are probably underestimated.

Newborn Screening for Spinal Muscular Atrophy in New York State: Clinical Outcomes From the First 3 Years.

BACKGROUND AND OBJECTIVES: Spinal muscular atrophy (SMA) was added to the Recommended Uniform Screening Panel (RUSP) in July 2018, largely on the basis of the availability and efficacy of newly-approved disease modifying therapies. New York State (NYS) started universal newborn screening for SMA in October 2018. The authors report the findings from the first 3 years of screening. METHODS: Statewide neonatal screening was conducted using DNA extracted from dried blood spots using a real-time quantitative polymerase chain reaction (qPCR) assay. Retrospective follow-up data were collected from 9 referral centers across the state on 34 infants. RESULTS: In the first three years since statewide implementation, nearly 650,000 infants have been screened for SMA. 34 babies screened positive and were referred to a neuromuscular specialty care center. The incidence remains lower than previously predicted. The majority (94%), including all infants with 2-3 copies of SMN2, have received treatment. Among treated infants, the overwhelming majority (97%; 29/30) have received gene replacement. All infants in this cohort with 3 copies of SMN2 are clinically asymptomatic post-treatment based on early clinical follow-up data. Infants with 2 copies of SMN2 are more variable in their outcomes. Electrodiagnostic outcomes data from a subgroup of patients (n=11) for whom pre- and post-treatment data demonstrated either improvement or no change in CMAP amplitude at last clinical follow-up compared to pre-treatment baseline. Most infants were treated before 6 weeks of age (median = 34.5 DOL; range 11-180). Delays and barriers to treatment identified by treating clinicians followed two broad themes: medical and non-medical. Medical delays most commonly reported were presence of AAV9 antibodies and elevated troponin I levels. Non-medical barriers included delays in obtaining insurance as well as insurance policies regarding specific treatment modalities. DISCUSSION: The findings from the NYS cohort of newborn screen-identified infants are consistent with other reports of improved outcomes from early diagnosis and treatment. Additional biomarkers of motor neuron health including electromyography can potentially be helpful in detecting pre-clinical decline.

Implementation of population-based newborn screening reveals low incidence of spinal muscular atrophy.

PURPOSE: Spinal muscular atrophy (SMA) was added to the Recommended Uniform Screening Panel (RUSP) in July 2018, following FDA approval of the first effective SMA treatment, and demonstration of feasibility of high-throughput newborn screening using a primary molecular assay. SMA newborn screening was implemented in New York State (NYS) on 1 October 2018. METHODS: Screening was conducted using DNA extracted from dried blood spots with a multiplex real-time quantitative polymerase chain reaction (qPCR) assay targeting the recurrent SMN1 exon 7 gene deletion. RESULTS: During the first year, 225,093 infants were tested. Eight screened positive, were referred for follow-up, and confirmed to be homozygous for the deletion. Infants with two or three copies of the SMN2 gene, predicting more severe, earlier-onset SMA, were treated with antisense oligonucleotide and/or gene therapy. One infant with ≥4 copies SMN2 also received gene therapy. CONCLUSION: Newborn screening permits presymptomatic SMA diagnosis, when treatment initiation is most beneficial. At 1 in 28,137 (95% confidence interval [CI]: 1 in 14,259 to 55,525), the NYS SMA incidence is 2.6- to 4.7-fold lower than expected. The low SMA incidence is likely attributable to imprecise and biased estimates, coupled with increased awareness, access to and uptake of carrier screening, genetic counseling, cascade testing, prenatal diagnosis, and advanced reproductive technologies.

Pain, Headache, and Other Non-motor Symptoms in Myasthenia Gravis.

PURPOSE OF REVIEW: Myasthenia gravis (MG) is traditionally conceptualized as a disease with purely motor manifestations. This paper reviews the supporting evidence and pathophysiology of non-motor symptoms in MG, including pain, headache, special sense and autonomic dysfunction, sleep disturbance, and cognitive and psychosocial issues. RECENT FINDINGS: Work in this area has been limited. Recent studies have identified bodily pain and headache as common complaints in patients with MG. A growing literature also suggests that there may be an association of MG and sleep disturbance (both obstructive sleep apnea and sleep cycle dysfunction). Few studies suggest some measurable abnormalities of olfaction, gustation, audition, and autonomic function. The cognitive and psychosocial aspects of MG represent an emerging area of clinical and research interest, but large-scale data is sparse in the USA. The pathophysiology of MG is complex, and our understanding of the immunologic basis of this disease is expanding. The classic view of MG as a purely motor disorder may be incomplete. Recent work highlights non-motor symptoms that may impact patient management and quality of life.