Alpha-B-crystallin is a member of the alpha-crystallin/small heat-shock protein (HSP) family and under various neuropathologic conditions accumulates in reactive astrocytes and degenerating neurons. In the 5-prime flanking region of the CRYAB gene on 11q22-q23, where a constitutive DNaseI hypersensitive site is located, Iwaki et al. (1997) identified a gene transcribed in the opposite direction. Analysis of its mRNA structure by RT-PCR and 5-prime/3-prime RACE revealed that this gene is composed of 2 exons and encodes a new member of the alpha-crystallin/hsp family. They termed the gene HSPB2. Iwaki et al. (1997) also determined the complete genomic structure of the rat homolog of HSPB2. Southern blot analysis demonstrated that HSPB2is expressed preferentially in skeletal muscle and heart but not in the lens, while the neighboring CRYAB gene is highly expressed in all 3 tissues. The 2 related genes are arranged in a head-to-head manner with an intergenic sequence of less than 1 kb, raising a possibility of shared regulatory elements for their expression.