Human karyopherin alpha2 (KPNA2), a member of the karyopherin alpha family, 
plays a key role in the nuclear import of proteins with a classical nuclear 
localization signal (NLS). KPNA2, as part of a karyopherin alpha-beta 
heterodimer, directly binds to the NLS of proteins and functions as an adaptor 
that binds NLS-containing proteins via karyopherin beta to the nuclear pore 
complex. The NLS protein-receptor complex is translocated through the pore by an 
energy-dependent mechanism. Recently, we have identified and mapped the gene for 
KPNA2 in close proximity to a translocation breakpoint within 17q23-q24 
associated with Russell-Silver syndrome (RSS). Therefore, we considered KPNA2 as 
a positional candidate gene for this heterogeneous disorder. RSS is mainly 
characterized by pre- and postnatal growth retardation, lateral asymmetry, and 
other dysmorphic features. Here, we present the genomic organization of the 
human KPNA2 gene with 11 exons spanning approximately 10 kb on chromosome 
17q23-q24. Screening for mutations within all exons and adjacent intronic 
sequences from 31 unrelated RSS patients revealed three single nucleotide 
polymorphisms (SNPs) in exons 1, 5, and 7, and five SNPs in introns 1, 4 (2 
SNPs), 8, and 9, respectively. No disease-related mutation was identified by 
comparing the sequence data of the RSS patients with their clinically normal 
parents and controls.