Repeat-directed isolation of a novel gene preferentially expressed from the maternal allele in human placenta

Using a repetitive sequence of tandemly arrayed pentanucleotides in the hum an H19 3'-flanking region, we isolated a phage clone (lambda PEN11) which l ocalized to chromosome 11p15.5. The lambda PEN11 phage encodes a 2.3-kb cDN A consisting of seven exons at least. The gene was mainly expressed in brai n and pancreas (and less abundantly in testis), and demonstrated differenti al allele usage, with maternal expression being predominant in placenta, wh ich indicates the gene is an atypical imprinted gene. While the pentamer re peat might contribute to this effect, it is also possible that the differen tial allele usage might reflect the local chromosomal structure known as th e imprinting domain.