Contributor: Gordon K. Klintworth
Ectopia lentis may occur as an isolated ocular disorder (simple ectopia lentis) or it may be a manifestation of a systemic disorder such as Marfan syndrome, homocystinuria and perhaps hyperlysinemia. Marfan syndrome is the most frequent inherited disease causing ectopia lentis. Simple ectopia lentis is usually inherited with an autosomal dominant mode of transmission. It is often congenital and associated with microphakia and spherophakia. The ectopic lens is often displaced superiorly and temporally. Some cases of simple ectopia lens are caused by a mutation in the FBNI gene. Other mutaions in this gene cause Marfan syndrome. The mutations responsible for Marfan syndrome presumably cause more severe derangements in composition of the microfibrils than those found in simple ectopia lentis. A specific type of ectopia lentis is ectopia lentis et pupillae.