Genes encoding components critical to the neuromuscular junction and acetylcholine receptor (AChR) clustering represent a major class of FADS disease genes, these include RAPSN [MIM 601592] [17, 18], DOK7 [MIM 610285] [19], and MUSK [MIM 601296] [20], as well as mutations in the subunits of the muscular nicotinic acetylcholine receptor (AChR) [17, 21]. The gene discussed is MUSK; the disease is fetal akinesia deformation sequence.