249 ORIGINAL ARTICLE J Med Genet: first published as 10.1136/jmg.40.4.249 on 1 April 2003. Downloaded from The imprinted region on human chromosome 7q32 extends to the carboxypeptidase A gene cluster: an imprinted candidate for Silver-Russell syndrome L Bentley, K Nakabayashi, D Monk, C Beechey, J Peters, Z Birjandi, F E Khayat, M Patel, M A Preece, P Stanier, S W Scherer, G E Moore ............................................................................................................................. J Med Genet 2003;40:249–256 See end of article for authors’ affiliations Imprinted gene(s) on human chromosome 7q32-qter have been postulated to be involved in intrauterine ....................... growth restriction associated with Silver-Russell syndrome (SRS) as 7-10% of patients have mUPD(7). Correspondence to: Three imprinted genes, MEST, MESTIT1, and COPG2IT1 on chromosome 7q32, are unlikely to cause L Bentley, Department of SRS since epigenetic and sequence mutation analyses have not shown any changes. One hundred Fetal and Maternal kilobases proximal to MEST lies a group of four carboxypeptidase A (CPA) genes. Since most imprinted Medicine, Institute of genes are found in clusters, this study focuses on analysing these CPAs for imprinting effects based on Reproductive and Developmental Biology, their proximity to an established imprinted domain. Firstly, a replication timing study across 7q32 Faculty of Medicine, showed that an extensive genomic region including the CPAs, MEST, MESTIT1, and COPG2IT1 repli- Imperial College, cates asynchronously. Subsequently, SNP analysis by sequencing RT-PCR products of CPA1, CPA2, Hammersmith Campus, CPA4, and CPA5 indicated preferential expression of CPA4. Pyrosequencing was used as a quantita- Du Cane Road, London tive approach, which confirmed predominantly preferential expression of the maternal allele and bial- W12 0NN, UK;
[email protected] lelic expression in brain.