We have cloned rat cDNA coding for dopamine-Beta-hydroxylase (DBH) and subsequently isolated seven recombinant Lambda-phages bearing human DBH-gene-inserts and constructed preliminary restriction maps of several DBH-genes and/or pseudogenes. From these preliminary data and from the literature we derive a set of hypotheses which propose that: a) DBH is encoded by a multigene family; b) DBH genes have undergone chromosomal rearrangements which involve sequences of repetitive DNA; c) DBH genes may show restriction fragment length polymorphisms (RFLP's) which could result from the interdispersed repetitive DNA and/or rearrangements which we detected in genomic clones; d) DBH gene RFLP's may show linkage to neuropsychiatric disorders such as schizophrenia and major affective illness which are hypothesized to involve catecholamine transmitters. To test these hypotheses we propose to submit human DBH genes to extensive structural analysis. Appropriate Lambda-genomic clone restriction fragments will be subcloned into phage M13 mp8/9 with the aims to 1) construct extensive restriction maps of DBH-genes, 2) screen human genomic Lambda-phage libraries using 3'-or 5' end-pieces as probes to isolate overlapping Lambda-clones (""""""""chromosome walking""""""""), 3) identify transcription initiation sites, 4) determine the sequence of DBH-genes, and 5) to screen controls, psychiatric patients, their first degree relatives and extended pedigrees for RFLPs and to determine whether any detected RFLPs show linkage to psychiatric illness. We will map the expression of DBH-genes in discrete areas of developing and adult human postmortem brain utilizing genomic DNA probes derived from specific regions of DBH-genes in a) measurements and structural characterizations of DBH mRNAs and b) assessment of the relative levels of DBH mRNA in individual neurons by in situ hybridization. These studies should elucidate regulatory structural features of DBH genes and determine whether alterations in DBH gene structure or expression are developmentally regulated. These investigations will form the basis for future studies of DBH genes and their possible role in neuropsychiatric syndromes.
