![]() Most cartilage is later converted to bone, except for the cartilage that continues to cover and protect the ends of bones and is present in the nose and external ears. Perlecan is also found in cartilage, a tough, flexible tissue that makes up much of the skeleton during early development. Specifically, it is found in part of the extracellular matrix called the basement membrane, which is a thin, sheet-like structure that separates and supports cells in many tissues. This protein is found in the extracellular matrix, which is the intricate lattice of proteins and other molecules that forms in the spaces between cells. This gene provides instructions for making a protein known as perlecan. Schwartz-Jampel syndrome is caused by mutations in the HSPG2 gene. ![]() They have recommended that the designation Schwartz-Jampel syndrome type 2 no longer be used. Researchers have since discovered that the condition they thought was Schwartz-Jampel syndrome type 2 is actually part of another disorder, Stüve-Wiedemann syndrome, which is caused by mutations in a different gene. Type 1 has the signs and symptoms described above, while type 2 has more severe bone abnormalities and other health problems and is usually life-threatening in early infancy. Researchers originally described two types of Schwartz-Jampel syndrome. Other bone abnormalities associated with Schwartz-Jampel syndrome include a protruding chest ( pectus carinatum ), abnormal curvature of the spine, flattened bones of the spine (platyspondyly), and joint abnormalities called contractures that further restrict movement. The long bones may also be abnormally curved (bowed). These bones are shortened and unusually wide at the ends, so affected individuals have short stature. Affected individuals may also be nearsighted and experience abnormal blinking or spasms of the eyelids (blepharospasm).Ĭhondrodysplasia affects the development of the skeleton, particularly the long bones in the arms and legs and the bones of the hips. This facial appearance is very specific to Schwartz-Jampel syndrome. Sustained contraction of muscles in the face leads to a fixed, "mask-like" facial expression with narrow eye openings ( blepharophimosis ) and pursed lips. This sustained muscle contraction causes stiffness that interferes with eating, sitting, walking, and other movements. Myotonia involves continuous tensing (contraction) of muscles used for movement (skeletal muscles) throughout the body. The specific features of Schwartz-Jampel syndrome vary widely. The muscle and bone abnormalities worsen in childhood, although most affected individuals have a normal lifespan. Either muscle stiffness or chondrodysplasia can appear first. The signs and symptoms of this condition become apparent sometime after birth, usually in early childhood. Schwartz-Jampel syndrome is a rare condition characterized by permanent muscle stiffness (myotonia) and bone abnormalities known as chondrodysplasia.
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