Cri-du-chat is a human contiguous gene deletion syndrome resulting from 
hemizygous deletions of chromosome 5p. Here we describe the isolation from 
within this interval of the human Semaphorin F (SEMAF) gene, a member of a 
family of proteins that has been implicated in axonal pathfinding. The human 
SEMAF gene covers at least 10% of the deleted region and defines a new class 
within this large gene family characterized by the presence of seven type 1 
thrombospondin repeats. Prominent expression of murine semaphorin F (Semaf) was 
observed in the mouse brain, consistent with a role for semaphorin F as a 
signaling molecule that guides axons or migrating neuronal precursors during 
development. The known functions of semaphorins and the interesting pattern of 
expression for Semaf suggest that haploinsufficiency for SEMAF may disrupt 
normal brain development and might lead to some of the features of Cri-du-chat.