- Structural and functional mutations of the perlecan gene cause Schwartz-Jampel syndrome, with myotonic myopathy and chondrodysplasia. Arikawa-Hirasawa, E., Le, A.H., Nishino, I., Nonaka, I., Ho, N.C., Francomano, C.A., Govindraj, P., Hassell, J.R., Devaney, J.M., Spranger, J., Stevenson, R.E., Iannaccone, S., Dalakas, M.C., Yamada, Y. Am. J. Hum. Genet. (2002)