Mapping of a novel SH3 domain protein and two proteins of unknown function to human chromosome 21

Down syndrome, caused by trisomy of human chromosome 21 (HSA21), is the most common autosomal form of mental retardation. To understand the aetiology of the syndrome we need to identify the genes involved. We have utilised the information generated by the various EST sequencing projects to enrich the transcription map of chromosome 21. Here we report the mapping of SH3P17 to 21q22.1 and the localisation of two genes previously mapped to HSA21 by Nagase and colleagues, KIAA0136 and KIAA0179 to 21q22.2 and 21q22.3, respectively. SH3P17 has unknown function but contains four SH3 domains. KIAA0136 shows no homology to a yeast open reading frame. Further investigation of these three genes will add to our functional understanding of HSA21.