Long-term follow-up of two sibs with Larsen syndrome possibly due to parental germ-line mosaicism.

Larsen syndrome is a heterogeneous (autosomal dominant or recessive) disorder of characteristic facial changes, multiple joint dislocations, and bone deformities. Few data on the adult presentation of the recessive form of this disorder have been reported; thus, we set out to describe two sibs thought to be affected with autosomal recessive Larsen syndrome who were evaluated as infants and later as adults. Aside from secondary joint changes and the presence of cataracts, changes described in children with autosomal recessive Larsen syndrome were noted. Three years after evaluation, the sister gave birth to a daughter with Larsen syndrome. This occurrence raises the possibility of germ-line mosaicism as the mode of inheritance in this family. Thus, germ-line mosaicism must be considered in the genetic counseling of families with Larsen syndrome in which neither parent appears affected. These patients also illustrate that despite the severe skeletal and joint deformities, the prognosis can be good with careful orthopedic management.