Mechanotransduction, the pathway by which mechanical forces are translated to biological signals, plays important but poorly characterized roles in physiology. PIEZOs are recently identified, widely expressed, mechanically activated ion channels that are hypothesized to play a role in mechanotransduction in mammals. Here, we describe two distinct PIEZO2 mutations in patients with a subtype of Distal Arthrogryposis Type 5 characterized by generalized autosomal dominant contractures with limited eye movements, restrictive lung disease, and variable absence of cruciate knee ligaments. Electrophysiological studies reveal that the two PIEZO2 mutations affect biophysical properties related to channel inactivation: both E2727del and I802F mutations cause the PIEZO2-dependent, mechanically activated currents to recover faster from inactivation, while E2727del also causes a slowing of inactivation. Both types of changes in kinetics result in increased channel activity in response to a given mechanical stimulus, suggesting that Distal Arthrogryposis Type 5 can be caused by gain-of-function mutations in PIEZO2. We further show that overexpression of mutated PIEZO2 cDNAs does not cause constitutive activity or toxicity to cells, indicating that the observed phenotype is likely due to a mechanotransduction defect. Our studies identify a type of channelopathy and link the dysfunction of mechanically activated ion channels to developmental malformations and joint contractures.congenital contractures | neuromuscular system | whole exome sequencing | whole genome sequencing
A case of isolated angiitis of the CNS was observed for 5 years. Initial response to cyclophosphamide was followed by relapse on therapy interruption. After renewed treatment, clinical stabilization was achieved despite progressive stenoses shown by angiography. The patient died of cyclophosphamide-induced myelodysplastic syndrome. Autopsy revealed lack of inflammation, vascular scarring, and amyloid angiopathy. We conclude that cure from isolated angiitis of the CNS is possible and that the risk of overtreatment should be minimized.
BackgroundMyelomeningocele (MMC) is a part of a complex neural tube defect and a disorder of the cerebrospinal fluid system. Pressure sores are a frequent complication for patients with MMC. Little is known about the risk factors for pressure sores in adults with MMC. The aim of this study was to investigate an association between the presence of pressure sores and other patient characteristics, in order to develop an improved strategy for the management of sores.MethodsA structured questionnaire regarding sores, medical condition, function and living factors was designed and sent to the 193 patients with MMC registered in the year 2003 at TRS, a National Centre for Rare Disorders in Norway.ResultsOut of 193 total, 87 patients participated and 71 patients (82%) reported sores; 26 (30%) at the time of the interview and 45 (52%) during the last 5 years. Sores were mostly localized on toes and feet and occurred exclusively in regions with reduced or missing sensibility. A significant association was found between sores and memory deficit (p = 0.02), Arnold Chiari malformation (p = 0.02) and a record of previous sores (p = 0.004). Sores were not significantly associated with hydrocephalus, syringomyelia, nutrition, body mass index, smoking, physical activity, employment or living together with other persons. Some patients (18, 21%) reported skin inspection by others and the remainder relied on self-inspection.ConclusionPatients with sensory deficit, memory problems, and Arnold Chiari malformation had a higher risk of having pressure sores. This patient group needs improved skin inspection routines and sore treatment.
• There are no data about ageing and life-long prognosis of amyoplasia. • Severe physical limitations in amyoplasia are compatible with a long and meaningful life. • Muscular force decreases during adult life. Therefore, a potential risk of overtraining should be considered.
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