G.P.159

Cylindrical spirals are morphological abnormalities, reported in fewer than 15 cases so far and presenting with a wide variety of clinical phenotypes. To clarify the nature of cylindrical spirals, we characterized the proteins in muscle specimens from two Chinese siblings presented clinically with muscle weakness and ultrastructurally with cylindrical spirals using a series of antibodies to sarcoplasmic reticulum and its related structures. On electron microscope, the cylindrical spirals are consisted of 10–20 lamellae wrapped around a central core containing glycogen granules. The immunohistochemical stains showed that all of these key calcium-regulatory proteins of the skeletal muscle sarcoplasmic reticulum, including SERCA1 (longitudinal sarcoplasmic reticulum), calsequestrin (terminal cisternae) and RyR1 (junctional sarcoplasmic reticulum) were expressed in cylindrical spirals. The T-tubule special resident DHPR and nuclear membrane protein emerin were also present in cylindrical spirals, while the Golgi apparatus marker GM130 and the myofilament protein myosin as well as the cellular skeleton protein desmin were not found in cylindrical spirals. Moreover, antibodies to LC3 and Lamp2 relevant to autophagosome and lysosome were negative. Taken together, these results suggested that cylindrical spirals could originate from the whole sarcoplasmic reticulum containing the junctional, longitudinal and cisternae components of the SR and consequently affected the calcium homeostasis.