Assignment of the protocadherin 20 (PCDH20) gene to tammar wallaby chromosome 6q by fluorescence in situ hybridisation

Abstract

Protocadherin genes are members of the cadherin superfamily and are thought to be involved in cell-cell recognition in the central nervous system. Cadherin genes are divided into two groups, classical and non-classical. Protocadherins are the major non-classical cadherins (Suzuki, 1996). In humans, PCDH20 maps to chromosome 13q21 (Yagi and Takeichi, 2000). PCDH20 is also known to map to mouse chromosome 18, rat chromosome 18p12→p11, and Chinese hamster chromosome 2q17 (Hirano et al., 1999, Ono et al., 2000). Marsupials are of particular value in comparative genetics because of their early divergence (about 130 million years ago) from eutherian mammals. In this study we cloned and mapped the genomic homologue of PCDH20 by fluorescence in situ hybridisation to the long arm of chromosome 6 in the model marsupial Macropus eugenii (tammar wallaby). PCDH20 is the first gene to be mapped to tammar wallaby chromosome 6 and may represent a newly defined region of homology between human chromosome 13 and wallaby chromosome 6. Secondary signals were also observed on the proximal region of the long arm of the X chromosome that could represent a related protocadherin gene in this region. Materials and methods