GENE ASSIGNMENT BY POLYMERASE CHAIN-REACTION - LOCALIZATION OF THE HUMAN POTASSIUM CHANNEL I-SK GENE TO THE DOWNS-SYNDROME REGION OF CHROMOSOME 21Q22.1-Q22.2

Gene mapping, using the polymerase chain reaction (PCR) on DNA obtaine d from a human/rodent hybrid cell line carrying only the human chromos ome 21, permitted the assignment of the human I-sK gene, encoding a sl owly activating potassium channel, to chromosome 21. PCR analysis of t wo complete panels of human/rodent hybrid DNA mapped I-sK to chromosom e 21 with 100% concordance. By performing PCR on DNA of a human chromo some 21 regional mapping panel the gene was sublocalized to chromosome 21q22.1-q22.2, which also contains the putative Down's syndrome (tris omy 21) region. The PCR product obtained from the hybrid cell line DNA carrying only human chromosome 21 was sequenced, thus confirming that the PCR product was derived from human I-sK.