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. Anomalies in neuromuscular junction 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 neuromuscular junction organization using fluorescence microscopy. Compared to spinalis muscle from control patients with idiopathic scoliosis or cerebral palsy, the patient with Escobar syndrome had a significantly higher degree of acetylcholine receptor present outside acetylcholinesterase; and significantly less acetylcholinesterase outside acetylcholine receptor. Given the role of the acetylcholine receotor γ-subunit in fetal neuromuscular signal transduction and in establishing the primary encounter of muscle and motor nerve terminal, the CHRNG mutation 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.