Close physical linkage of the FLT1 and FLT3 genes on chromosome 13 in man and chromosome 5 in mouse.

Receptor-type tyrosine kinases (RTK) with five or seven immunoglobulin-like domains in their extracellular region are encoded by genes grouped in clusters. In human, two such clusters have been individualized, in chromosomal regions 4q11-q12 and 5q33-qter respectively. We define here a third cluster located on chromosome 13q and containing two contiguous RTK genes, FLT1 and FLT3. The former has recently been shown to encode a RTK of a new class while the latter codes for a hematopoietic receptor closely related to the products of the FMS and KIT genes. The physical linkage is also evidenced in mouse, where the two genes appear to lie within a 350 kb Mlu I fragment, on mouse chromosome 5.