Congenital tremor and myopathy secondary to novel MYBPC1 variant

Congenital myopathy with tremor (MYOTREM) is a recently described disorder characterized by mild myopathy and a postural and intention tremor present since early infancy. MYOTREM is associated with pathogenic variants in MYBPC1 which encodes slow myosin-binding protein C, a sarcomere protein with regulatory and structural roles. Here, we describe a family with three generations of variably affected members exhibiting a novel variant in MYBPC1 (c.656 T > C, p.Leu219Pro). Among the unique features of affected family members is the persistence of tremor in sleep. We also present the first muscle magnetic resonance images for this disorder, and report muscle atrophy and fatty infiltration.

Tuberous sclerosis complex associated intracranial lesion found by antenatal ultrasound

Tuberous sclerosis complex (TSC) is characterized by the growth of benign tumors in the skin, brain, kidneys, lung and heart [1]. Prognosis is mostly determined by the extent of brain involvement as tumors in the brain lead to seizures, cognitive impairment and behavioral problems. Current evidence suggests anti-epileptic treatment before the onset of seizures reduces epilepsy severity and risk of cognitive impairment in TSC however identifying these children prior to the onset of seizures is challenging. Our case shows retrospectively reviewed antenatal ultrasounds of a male child diagnosed postnatally at 12 days of life with TSC. Analysis found a soft tissue mass in the right ventricle on antenatal ultrasound which was not captured in the initial ultrasound report. Though there are no reports of sensitivity of neurosonography for the antenatal detection of intracranial abnormalities associated with TSC, our case suggests that antenatal ultrasound could be used as a screening modality for antenatal diagnosis of TSC.

Lethal Neonatal Rigidity and Multifocal Seizure Syndrome--A Misnamed Disorder?

OBJECTIVE

Lethal neonatal rigidity and multifocal seizure syndrome is a newly recognized genetic disorder associated with early onset of rigidity, multifocal epilepsy, developmental arrest, and early death. It is an autosomal recessive condition resulting from a mutation in the BRAT1 (BRCA1 [breast cancer-1]-associated ataxia telangiectasia mutated activator 1) gene. There are few cases in the literature, and all patients have died before age 2 years, most within the first 6 months of life. The objective of this report is to expand the phenotypic spectrum of BRAT1 disorders and propose new nomenclature for this condition.

RESULTS

We describe a child with compound heterozygosity for mutations in BRAT1. Her neonatal course was unremarkable. Over the first year of life she was noted to have progressive global developmental delay, visual impairment, microcephaly, hypertonia, hyperreflexia, and seizures. No epileptiform discharges were seen on electroencephalogram. Serial magnetic resonance imaging of the brain showed progressive cerebellar and brainstem atrophy. Unlike previously described patients, our patient has gained a number of developmental skills and, at this time, is 3 years and 8 months old.

CONCLUSION

Despite the name of this disorder, patients with lethal neonatal rigidity and multifocal seizure syndrome may not present until after the neonatal period and may have a much longer life span than previously reported. We suggest renaming the condition "BRAT1-associated neurodegenerative disorder" to avoid the assumptions associated with the original nomenclature and to encourage clinicians to consider this condition outside the neonatal period.

Full-length and fragmented netrin-1 in multiple sclerosis plaques are inhibitors of oligodendrocyte precursor cell migration

Oligodendrocytes exhibit a limited capacity to remyelinate in multiple sclerosis. Factors present in multiple sclerosis lesions are thought to inhibit oligodendrocyte precursor cell migration, limiting their recruitment to axons requiring remyelination; however, few inhibitors have been identified. A candidate inhibitor is netrin-1, a secreted protein that repels migrating oligodendrocyte precursor cells during neural development and is expressed by myelinating oligodendrocytes in the mature rodent central nervous system. Herein, we examined the distribution of netrin-1 in adult human white matter and multiple sclerosis lesions. We detected full-length netrin-1 protein and shorter netrin-1 fragments in samples of normal white matter and of multiple sclerosis lesions from adult human brain. We demonstrate that peptides corresponding to amino terminal domains VI and V of netrin-1 repel migrating oligodendrocyte precursor cells, but lack the chemoattractant activity of full-length netrin-1. Furthermore, recombinant domains VI-V of netrin-1 disrupt the chemoattractant activity of full-length netrin-1, consistent with a competitive mechanism of action. These findings indicate that full-length and fragmented forms of netrin-1, found in multiple sclerosis lesions, have the capacity to inhibit oligodendrocyte precursor migration, identifying netrin-1 as a potential target for therapies that promote remyelination.