The Escobar variant of multiple pterygium syndrome (OMIM #265000) is a rare, 
autosomal recessive disorder associated with mutations in the γ-subunit of the 
nicotinic acetylcholine receptor (CHRNG). CHRNG is expressed in fetal muscle 
during motor development and contributes to the formation of neuromuscular 
junctions (NMJs). Anomalies in NMJ structure and function have not been 
investigated in patients with Escobar syndrome. We report five patients 
identified as having Escobar syndrome, from four families. In three families, 
the same mutation (c.459dupA) was identified in CHRNG. A biopsy from 
brachioradialis muscle was collected from a patient from one of these families 
and analyzed for NMJ organization using fluorescence microscopy. Compared to 
spinalis muscle from control patients with idiopathic scoliosis or cerebral 
palsy (CP), the patient with Escobar syndrome had a significantly higher degree 
of acetylcholine receptor present outside acetylcholinesterase and significantly 
less acetylcholinesterase outside acetylcholine receptors. Given the role of the 
acetylcholine receptor γ-subunit in fetal neuromuscular signal transduction and 
in establishing the primary encounter of muscle and motor nerve terminal, the 
CHRNG mutations described in Escobar syndrome may cause a broader disruption of 
postsynaptic proteins and result in aberrant development of the NMJ due to 
impaired prenatal neuromuscular transmission and/or abnormal neuromuscular 
synaptogenesis.