PIEZO2 deficiency is a recognizable arthrogryposis syndrome: A new case and literature review.

PIEZO2 encodes a mechanically activated cation channel, which is abundantly expressed in dorsal root ganglion neuron and sensory endings of proprioceptors required for light touch sensation and proprioception in mice. Biallelic loss-of-function mutations in PIEZO2 (i.e., PIEZO2 deficiency) were recently found to cause an arthrogryposis syndrome. Sixteen patients from eight families have been reported to date. Herein we report a new case, including detailed clinical characteristics and courses as well as comprehensive neurological features. The patient was a 12-year-old girl presenting with congenital multiple contractures, progressive severe scoliosis, prenatal-onset growth impairment, motor developmental delay with hypotonia and myopathy-like muscle pathology, mild facial features, and normal intelligence. Her neurological features included areflexia, impaired proprioception, and decreased senses. Neurophysiological examination revealed decreased amplitude of sensory nerve action potentials, absent H reflex, and prolongation of central conduction times. Clinical exome sequencing revealed a novel homozygous frameshift mutation in PIEZO2 (NM_022068: c.4171_4174delGTCA: p.Val1391Lysfs*39) with no detectable mRNA expression of the gene. PIEZO2 deficiency represents a clinical entity involving characteristic neuromuscular abnormalities and physical features. Next generation sequencing-based comprehensive molecular screening and extensive neurophysiological examination could be valuable for diagnosis of the disorder.

Molecular mechanism for distinct neurological phenotypes conveyed by allelic truncating mutations.

The molecular mechanisms by which different mutations in the same gene can result in distinct disease phenotypes remain largely unknown. Truncating mutations of SOX10 cause either a complex neurocristopathy designated PCWH or a more restricted phenotype known as Waardenburg-Shah syndrome (WS4; OMIM 277580). Here we report that although all nonsense and frameshift mutations that cause premature termination of translation generate truncated SOX10 proteins with potent dominant-negative activity, the more severe disease phenotype, PCWH, is realized only when the mutant mRNAs escape the nonsense-mediated decay (NMD) pathway. We observe similar results for truncating mutations of MPZ that convey distinct myelinopathies. Our experiments show that triggering NMD and escaping NMD may cause distinct neurological phenotypes.

The treatment of hemimandibular hyperplasia preserving enlarged condylar head.

OBJECTIVE: To present a case of hemimandibular hyperplasia (HH) treated with orthognathic surgery that preserves the condyle without disturbing mandibular function. METHODS: A 27-year-old woman with HH was treated with orthognathic surgery preserving the enlarged condylar head. Radiographic examination showed typical enlargement of the right condyle, elongation of the right ascending ramus and mandibular body, and tilted occlusal plane. A mandibular sagittal split osteotomy on the unaffected side and subcondylar ramus osteotomy on the affected side, Le Fort I wedge osteotomy to relevel the tilted occlusal plane, and contouring of the lower mandibular margin were performed. RESULTS: Excellent results in the full-face appearance and occlusion were obtained. There was no change in the size of the reserved condylar head 4 years postoperatively. In a series of examinations of jaw function with electromyography, mandibular kinesiography, and computer-aided diagnostic axiography, more favorable findings were obtained postoperatively. CONCLUSIONS: In a case of HH without abnormally high growth activity, orthognathic surgery preserving hypertrophic condyle produced functional improvement in addition to good occlusal and aesthetic outcomes.